We review what could be astronomy from the Moon in the next decades in the visible domain.
After a short review observational approaches, from photometry to high contrast and high angular
resolution imaging, We essentially focus on some promising scientific objectives, from Solar
System to the extragalactic domain. At the end, I add a proposal to use the Earth-Moon system to
test fundamental physics. Since this meeting is dedicated to the next decades of Astronomy from
the Moon, we consider projects and science objectives for several decades from now.
Orbital configurations of spaceborne interferometers for studying photon ring...Sérgio Sacani
Recent advances in technology coupled with the progress of observational
radio astronomy methods resulted in achieving a major milestone of astrophysics - a direct image of the shadow of a supermassive black hole, taken
by the Earth-based Event Horizon Telescope (EHT). The EHT was able to
achieve a resolution of ∼20 µas, enabling it to resolve the shadows of the
black holes in the centres of two celestial objects: the supergiant elliptical
galaxy M87 and the Milky Way Galaxy. The EHT results mark the start of a
new round of development of next generation Very Long Baseline Interferometers (VLBI) which will be able to operate at millimetre and sub-millimetre
wavelengths. The inclusion of baselines exceeding the diameter of the Earth
and observation at as short a wavelength as possible is imperative for further development of high resolution astronomical observations. This can be
achieved by a spaceborne VLBI system. We consider the preliminary mission
design of such a system, specifically focused on the detection and analysis
of photon rings, an intrinsic feature of supermassive black holes. Optimised
Earth, Sun-Earth L2 and Earth-Moon L2 orbit configurations for the space
interferometer system are presented, all of which provide an order of magnitude improvement in resolution compared to the EHT. Such a space-borne
Solar system as a radio telescope by the formation of virtual lenses above an...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Solar system as a radio telescope by the formation of virtual lenses above an...eSAT Journals
Abstract The boundaries of multiverse are almost infinite and so the thirst of mankind for latest technology .man has startled many principles of space and nature by gaining them facing all fatal difficulties. Time is one quantity which is considered to be fast happening, but when it comes to happenings in space it is faster. All what we look into space is past; under least possible cases we could see the present. So, there has a necessicity for us to keep a big eye on making our search for extra-galactic recourses or extra-celestial life forms etc with equal speeds of space time. for this to be achieved by us we need to make some drastic changes in our telescope usage and we have to adopt technological up gradation and we should no longer make our telescope concentrate on the same celestial body for days continuously , indeed mili seconds should be enough to grab the required information . Index Terms- RTS, LEO, MEO, GEO, RT
Adaptive optics are used in ground-based telescopes to directly image extrasolar planets and overcome atmospheric turbulence. Atmospheric turbulence causes distortions that blur planetary images. Adaptive optics systems measure wavefront distortions using a wavefront sensor and correct for them using a deformable mirror in a closed-loop system. This results in sharper, diffraction-limited images that help verify exoplanets. Future extremely large telescopes will use many more actuators on deformable mirrors to provide substantial correction, aiding the search for Earth-like exoplanets.
Water vapour absorption in the clear atmosphere of a Neptune-sized exoplanetGOASA
1) The transmission spectrum of the exoplanet HAT-P-11b was observed using Hubble and Spitzer space telescopes.
2) Water vapor absorption was detected at 1.4 micrometers in the atmosphere, indicating a clear atmosphere down to 1 mbar pressure.
3) The detection of water vapor and relatively large atmospheric scale height places an upper limit on the abundance of heavy elements in the atmosphere of around 700 times the solar value, consistent with core accretion planet formation theories.
Studies of ngc_6720_with_calibrated_hst_wfc3_emission_line_filter_imagesSérgio Sacani
This study uses calibrated Hubble Space Telescope images of the Ring Nebula (NGC 6720) taken 12.925 years apart to measure tangential motions within the nebula. Individual features were measured in nitrogen emission line images as well as dark knots seen against oxygen emission. The results indicate that the nebula is expanding homologously, but at a faster rate along its major axis. Dark knots were found to expand more slowly than the nebular gas. The tangential motion measurements allow estimates of the nebula's distance and dynamic age to be about 720 pc and 4000 years, respectively.
Water vapour absorption_in_the_clear_atmosphere_of_a_neptune_sized_exoplanetSérgio Sacani
This document summarizes research on the transmission spectrum of the exoplanet HAT-P-11b, a Neptune-sized planet. Observations from the Hubble Space Telescope and Spitzer Space Telescope detected water vapor absorption in the planet's atmosphere at a wavelength of 1.4 micrometers. Analysis of the spectrum indicates the atmosphere is predominantly clear down to 1 mbar and has a hydrogen abundance similar to solar values. Atmospheric modeling suggests a metallicity around 190 times that of the Sun's, in agreement with core accretion planet formation theories. This makes HAT-P-11b the smallest exoplanet to date with a detected molecular signature in its atmosphere, providing new insights into the composition and formation of Neptune-sized
This document summarizes the results of a sub-mm survey of the Carina Nebula complex conducted with the LABOCA instrument on the APEX telescope. The survey mapped an area of 1.25° × 1.25° at 870 μm, revealing the morphology and distribution of cold dust clouds with masses down to a few solar masses. The total mass of clouds detected is estimated to be around 60,000 M☉. The cloud morphologies range from large clouds of several thousand solar masses to small diffuse clouds of only a few solar masses. The distribution of sub-mm emission generally agrees with Spitzer 8 μm maps, identifying clouds interacting with massive stars as well as infrared dark clouds. The survey provides crucial
Orbital configurations of spaceborne interferometers for studying photon ring...Sérgio Sacani
Recent advances in technology coupled with the progress of observational
radio astronomy methods resulted in achieving a major milestone of astrophysics - a direct image of the shadow of a supermassive black hole, taken
by the Earth-based Event Horizon Telescope (EHT). The EHT was able to
achieve a resolution of ∼20 µas, enabling it to resolve the shadows of the
black holes in the centres of two celestial objects: the supergiant elliptical
galaxy M87 and the Milky Way Galaxy. The EHT results mark the start of a
new round of development of next generation Very Long Baseline Interferometers (VLBI) which will be able to operate at millimetre and sub-millimetre
wavelengths. The inclusion of baselines exceeding the diameter of the Earth
and observation at as short a wavelength as possible is imperative for further development of high resolution astronomical observations. This can be
achieved by a spaceborne VLBI system. We consider the preliminary mission
design of such a system, specifically focused on the detection and analysis
of photon rings, an intrinsic feature of supermassive black holes. Optimised
Earth, Sun-Earth L2 and Earth-Moon L2 orbit configurations for the space
interferometer system are presented, all of which provide an order of magnitude improvement in resolution compared to the EHT. Such a space-borne
Solar system as a radio telescope by the formation of virtual lenses above an...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Solar system as a radio telescope by the formation of virtual lenses above an...eSAT Journals
Abstract The boundaries of multiverse are almost infinite and so the thirst of mankind for latest technology .man has startled many principles of space and nature by gaining them facing all fatal difficulties. Time is one quantity which is considered to be fast happening, but when it comes to happenings in space it is faster. All what we look into space is past; under least possible cases we could see the present. So, there has a necessicity for us to keep a big eye on making our search for extra-galactic recourses or extra-celestial life forms etc with equal speeds of space time. for this to be achieved by us we need to make some drastic changes in our telescope usage and we have to adopt technological up gradation and we should no longer make our telescope concentrate on the same celestial body for days continuously , indeed mili seconds should be enough to grab the required information . Index Terms- RTS, LEO, MEO, GEO, RT
Adaptive optics are used in ground-based telescopes to directly image extrasolar planets and overcome atmospheric turbulence. Atmospheric turbulence causes distortions that blur planetary images. Adaptive optics systems measure wavefront distortions using a wavefront sensor and correct for them using a deformable mirror in a closed-loop system. This results in sharper, diffraction-limited images that help verify exoplanets. Future extremely large telescopes will use many more actuators on deformable mirrors to provide substantial correction, aiding the search for Earth-like exoplanets.
Water vapour absorption in the clear atmosphere of a Neptune-sized exoplanetGOASA
1) The transmission spectrum of the exoplanet HAT-P-11b was observed using Hubble and Spitzer space telescopes.
2) Water vapor absorption was detected at 1.4 micrometers in the atmosphere, indicating a clear atmosphere down to 1 mbar pressure.
3) The detection of water vapor and relatively large atmospheric scale height places an upper limit on the abundance of heavy elements in the atmosphere of around 700 times the solar value, consistent with core accretion planet formation theories.
Studies of ngc_6720_with_calibrated_hst_wfc3_emission_line_filter_imagesSérgio Sacani
This study uses calibrated Hubble Space Telescope images of the Ring Nebula (NGC 6720) taken 12.925 years apart to measure tangential motions within the nebula. Individual features were measured in nitrogen emission line images as well as dark knots seen against oxygen emission. The results indicate that the nebula is expanding homologously, but at a faster rate along its major axis. Dark knots were found to expand more slowly than the nebular gas. The tangential motion measurements allow estimates of the nebula's distance and dynamic age to be about 720 pc and 4000 years, respectively.
Water vapour absorption_in_the_clear_atmosphere_of_a_neptune_sized_exoplanetSérgio Sacani
This document summarizes research on the transmission spectrum of the exoplanet HAT-P-11b, a Neptune-sized planet. Observations from the Hubble Space Telescope and Spitzer Space Telescope detected water vapor absorption in the planet's atmosphere at a wavelength of 1.4 micrometers. Analysis of the spectrum indicates the atmosphere is predominantly clear down to 1 mbar and has a hydrogen abundance similar to solar values. Atmospheric modeling suggests a metallicity around 190 times that of the Sun's, in agreement with core accretion planet formation theories. This makes HAT-P-11b the smallest exoplanet to date with a detected molecular signature in its atmosphere, providing new insights into the composition and formation of Neptune-sized
This document summarizes the results of a sub-mm survey of the Carina Nebula complex conducted with the LABOCA instrument on the APEX telescope. The survey mapped an area of 1.25° × 1.25° at 870 μm, revealing the morphology and distribution of cold dust clouds with masses down to a few solar masses. The total mass of clouds detected is estimated to be around 60,000 M☉. The cloud morphologies range from large clouds of several thousand solar masses to small diffuse clouds of only a few solar masses. The distribution of sub-mm emission generally agrees with Spitzer 8 μm maps, identifying clouds interacting with massive stars as well as infrared dark clouds. The survey provides crucial
The extremely high albedo of LTT 9779 b revealed by CHEOPSSérgio Sacani
Optical secondary eclipse measurements of small planets can provide a wealth of information about the reflective properties
of these worlds, but the measurements are particularly challenging to attain because of their relatively shallow depth. If such signals
can be detected and modeled, however, they can provide planetary albedos, thermal characteristics, and information on absorbers in
the upper atmosphere.
Aims. We aim to detect and characterize the optical secondary eclipse of the planet LTT 9779 b using the CHaracterising ExOPlanet
Satellite (CHEOPS) to measure the planetary albedo and search for the signature of atmospheric condensates.
Methods. We observed ten secondary eclipses of the planet with CHEOPS. We carefully analyzed and detrended the light curves using
three independent methods to perform the final astrophysical detrending and eclipse model fitting of the individual and combined light
curves.
Results. Each of our analysis methods yielded statistically similar results, providing a robust detection of the eclipse of LTT 9779 b
with a depth of 115±24 ppm. This surprisingly large depth provides a geometric albedo for the planet of 0.80+0.10
−0.17, consistent with
estimates of radiative-convective models. This value is similar to that of Venus in our own Solar System. When combining the eclipse
from CHEOPS with the measurements from TESS and Spitzer, our global climate models indicate that LTT 9779 b likely has a super
metal-rich atmosphere, with a lower limit of 400× solar being found, and the presence of silicate clouds. The observations also reveal
hints of optical eclipse depth variability, but these have yet to be confirmed.
Conclusions. The results found here in the optical when combined with those in the near-infrared provide the first steps toward
understanding the atmospheric structure and physical processes of ultrahot Neptune worlds that inhabit the Neptune desert.
Parallax is the apparent change in position of an object when viewed from different positions. It can be used to measure distances to celestial objects. Stellar parallax involves measuring the difference in the position of a nearby star observed from opposite sides of Earth's orbit around the Sun. This allows astronomers to determine the star's distance using trigonometry. In 1989, the Hipparcos satellite improved parallax measurements for over 100,000 nearby stars. The Gaia satellite, launched in 2013, can measure parallax angles to greater accuracy, mapping stars up to tens of thousands of light years away.
First results from_the_hubble_opal_program_jupiter_in_2015Sérgio Sacani
Os cientistas usando o Telescópio Espacial Hubble da NASA/ESA produziram novos mapas de Júpiter, que mostram as contínuas mudanças que ocorrem com a famosa Grande Mancha Vermelha. As imagens também revelam uma rara estrutura em forma de onda na atmosfera do planeta que não tinha sido vista por décadas. A nova imagem é a primeira de uma série de retratos anuais dos planetas externos do Sistema Solar, que nos darão um novo olhar desses mundos remotos, e ajudarão os cientistas a estudarem como eles mudam com o passar do tempo.
Nessa nova imagem de Júpiter, uma grande quantidade de feições foi capturada incluindo ventos, nuvens e tempestades. Os cientistas por trás dessas novas imagens, as obtiveram usando a Wide Field Camera 3 do Hubble, num período de observação de mais de 10 horas e produziram assim dois mapas completos do planeta, a partir das suas observações. Esses mapas fizeram com que fosse possível determinar a velocidade dos ventos em Júpiter, com a finalidade de identificar diferentes fenômenos na sua atmosfera além de traquear as suas feições mais famosas.
As novas imagens confirmam que a grande tempestade que tem existido na superfície de nuvens de Júpiter por no mínimo 300 anos, continua a encolher, mas mesmo que desapareça, ela irá morrer lutando. A tempestade, conhecida como Grande Mancha Vermelha, é vista aqui fazendo seus movimentos em espiral no centro da imagem do planeta. Ela tem diminuído de tamanho de maneira muito rápida de ano em ano. Mas agora, a taxa de encolhimento parece ter reduzido novamente, mesmo apesar da mancha ser cerca de 240 quilômetros menor do que era em 2014.
The long period_galactic_cepheid_rs_puppisSérgio Sacani
This document summarizes an observational study that uses light echoes to determine the geometric distance to the Cepheid variable star RS Puppis. Images of RS Puppis and its surrounding nebula were taken over multiple epochs with the ESO NTT telescope to track the progression of light variations within the nebula. Photometric measurements of the phase lag in several nebula regions were used to derive a geometric distance of 1,992 ± 28 parsecs to RS Puppis, one of the most accurate distances yet measured to a Cepheid variable star.
This document provides an outline and overview of key concepts in astronomy related to light and telescopes. It discusses:
1. The electromagnetic spectrum and different types of electromagnetic radiation used in astronomy like visible light, infrared, ultraviolet, X-rays, and radio waves.
2. Optical telescopes and their components like lenses, mirrors, and eyepieces. It also covers concepts like light gathering power, resolving power, and magnification.
3. Modern telescope designs that are lighter, computer-controlled, and use techniques like adaptive optics to improve image quality.
4. Other types of telescopes like radio telescopes and how interferometry is used to improve their resolving power by combining signals from
•Lunar laser telemetry consists in determining the round-trip travel time of the light between a transmitter on the Earth and a reflector on the Moon, which is an equivalent measurement of the distance between these two points
The muse 3_d_view_of_the_hubble_deep_field_southSérgio Sacani
Artigo mostra como foram as observações feitas com o MUSE, o novo instrumento do VLT do campo profundo do Hubble. Além de descobrir 20 novos objetos, o MUSE conseguiu medir as propriedades das galáxias e até representar as mais próximas em 3 dimensões.
Fluorescence detector Array of Single-pixel Telescopes (FAST) projectToshihiro FUJII
This document discusses the history and development of fluorescence detection techniques for ultra-high energy cosmic rays (UHECR). It proposes a new concept called the Fluorescence detector Array of Single-pixel Telescopes (FAST) project. FAST aims to develop an optimized and economical fluorescence detector array to observe UHECRs above 1019.5 eV over a large area. The document outlines the design of FAST stations and reports on an initial test using the EUSO-TA prototype that successfully detected laser pulses and UHECR signals. It concludes by discussing plans to construct a new full-scale FAST prototype and the potential for FAST to increase UHECR exposure and help resolve questions about their origin.
The document summarizes the prospect of UV observations from the Moon using a proposed UV telescope called LUCI. Some key points:
1. LUCI would be a small UV telescope (30cm aperture) to be deployed on the lunar surface by Team Indus, to take advantage of the Moon's stable environment for UV astronomy.
2. The telescope would image bright UV sources like stars and nebulae to magnitudes of 12 to study transients and variability. It would cover 60 square degrees in a lunar day.
3. The design and calibration of LUCI's optics, structure, detectors, and electronics are described, showing it can meet weight and size constraints for deployment on the lunar lander while achieving the
Measurements of the_near_nucleus_coma_of_comet_67_p_churyumov_gerasimenko_wit...Sérgio Sacani
Artigo descreve descoberta feita pelo instrumento Alice da sonda Rosetta no cometa 67P/Churyumov-Gerasimenko, das moléculas de água e dióxido de carbono quebradas que pairam pela atmosfera do cometa.
Spectroscopy and thermal modelling of the first interstellar object 1I/2017 U...Sérgio Sacani
During the formation and evolution of the Solar System, significant
numbers of cometary and asteroidal bodies were
ejected into interstellar space1,2. It is reasonable to expect that
the same happened for planetary systems other than our own.
Detection of such interstellar objects would allow us to probe
the planetesimal formation processes around other stars, possibly
together with the effects of long-term exposure to the
interstellar medium. 1I/2017 U1 ‘Oumuamua is the first known
interstellar object, discovered by the Pan-STARRS1 telescope
in October 2017 (ref. 3). The discovery epoch photometry
implies a highly elongated body with radii of ~ 200 × 20 m
when a comet-like geometric albedo of 0.04 is assumed. The
observable interstellar object population is expected to be
dominated by comet-like bodies in agreement with our spectra,
yet the reported inactivity of 'Oumuamua implies a lack
of surface ice. Here, we report spectroscopic characterization
of ‘Oumuamua, finding it to be variable with time but similar
to organically rich surfaces found in the outer Solar System.
We show that this is consistent with predictions of an insulating
mantle produced by long-term cosmic ray exposure4.
An internal icy composition cannot therefore be ruled out by
the lack of activity, even though ‘Oumuamua passed within
0.25 au of the Sun.
Mapping spiral structure on the far side of the Milky WaySérgio Sacani
Little is known about the portion of the Milky Way lying beyond the Galactic center at distances
of more than 9 kiloparsec from the Sun. These regions are opaque at optical wavelengths
because of absorption by interstellar dust, and distances are very large and hard to measure.
We report a direct trigonometric parallax distance of 20:4þ2:8
2:2 kiloparsec obtained with the Very
Long Baseline Array to a water maser source in a region of active star formation. These
measurements allow us to shed light on Galactic spiral structure by locating the ScutumCentaurus
spiral arm as it passes through the far side of the Milky Way and to validate a
kinematic method for determining distances in this region on the basis of transverse motions.
Spitzer as microlens_parallax_satellite_mass_measurement_for_exoplanet_and_hi...Sérgio Sacani
This document summarizes a study using Spitzer and ground-based observations to measure the microlens parallax vector πE for the first time for a planetary microlensing event, OGLE-2014-BLG-0124L. The πE measurement allows the mass and distance of the planet and its host star to be determined. Spitzer observations provided a 2.5% precision measurement of πE, substantially improving upon the 22% precision from ground data alone. The planet has a mass of about 0.5 Jupiter masses and orbits a star of about 0.7 solar masses at a projected distance of about 3.1 AU.
MAGIA satellite. Experimental Astronomy (8 December 2010), pp. 1-20Stefano Coltellacci
The document describes the MAGIA satellite mission, which aims to study the Moon's internal structure, polar regions, and exosphere. The satellite will carry a suite of instruments including cameras, an altimeter, particle detectors, and accelerometers. It will be launched via Soyuz rocket into a lunar transfer orbit, then enter a polar mapping orbit for 6 months before transitioning to a gravity science orbit. Key challenges include meeting tight budget constraints while achieving ambitious science goals and accommodating multiple payloads and propulsion systems for orbital maneuvers.
No global pluto_like_atmosphere_on_dwarf_planet_makemake_from_a_stellar_occul...Sérgio Sacani
1. A stellar occultation event was observed involving the dwarf planet Makemake on April 23, 2011 using multiple telescopes.
2. Analysis of the light curves from the event showed abrupt disappearances and reappearances of the star, indicating Makemake has no global atmosphere at an upper limit of 4-12 nanobar surface pressure.
3. The occultation data was used to determine Makemake has dimensions of 1,430±9 km by 1,502±45 km, implying a high geometric albedo of 0.77±0.03. This rules out a low density and suggests Makemake is in hydrostatic equilibrium as an oblate spheroid.
This document summarizes a blind HI survey of the southern Milky Way zone of avoidance conducted with the Parkes radio telescope. The survey detected 883 galaxies at Galactic longitudes 212° < l < 36° and latitudes |b| < 5° to a sensitivity of 6 mJy per 27 km/s channel. Fifty-one percent of detections had known optical/near-infrared counterparts, while 27% had new counterparts identified. The survey delineated large-scale structures in the Puppis and Great Attractor regions for the first time. Several newly identified galaxy concentrations and clusters were revealed that help trace the Great Attractor Wall.
The Possible Tidal Demise of Kepler’s First Planetary SystemSérgio Sacani
We present evidence of tidally-driven inspiral in the Kepler-1658 (KOI-4) system, which consists of a giant planet
(1.1RJ, 5.9MJ) orbiting an evolved host star (2.9Re, 1.5Me). Using transit timing measurements from Kepler,
Palomar/WIRC, and TESS, we show that the orbital period of Kepler-1658b appears to be decreasing at a rate = -
+ P 131 22
20 ms yr−1
, corresponding to an infall timescale P P » 2.5 Myr. We consider other explanations for the
data including line-of-sight acceleration and orbital precession, but find them to be implausible. The observed
period derivative implies a tidal quality factor
¢ = ´ -
+ Q 2.50 10 0.62
0.85 4, in good agreement with theoretical
predictions for inertial wave dissipation in subgiant stars. Additionally, while it probably cannot explain the entire
inspiral rate, a small amount of planetary dissipation could naturally explain the deep optical eclipse observed for
the planet via enhanced thermal emission. As the first evolved system with detected inspiral, Kepler-1658 is a new
benchmark for understanding tidal physics at the end of the planetary life cycle
How do engines make a gps for the milky way possibleBurraqITSloution
The Moons project aims to map the Milky Way galaxy in 3D by using a new spectrograph instrument called Moons installed on the Very Large Telescope in Chile. Moons will be able to simultaneously observe the spectra of 1,001 astronomical objects, providing more detailed information about their composition and motion than images alone. This will allow astronomers to see deeper into the galaxy and create the first comprehensive 3D map of the Milky Way, functioning like a "GPS" for navigation within the galaxy. Key to Moons' ability to precisely position its 1,001 optical fibers is the use of high-precision stepper motors and gears from Faulhaber, without which the project would not be possible. Moons is expected to
X-rays from a Central “Exhaust Vent” of the Galactic Center ChimneySérgio Sacani
Using deep archival observations from the Chandra X-ray Observatory, we present an analysis of
linear X-ray-emitting features located within the southern portion of the Galactic center chimney,
and oriented orthogonal to the Galactic plane, centered at coordinates l = 0.08◦
, b = −1.42◦
. The
surface brightness and hardness ratio patterns are suggestive of a cylindrical morphology which may
have been produced by a plasma outflow channel extending from the Galactic center. Our fits of the
feature’s spectra favor a complex two-component model consisting of thermal and recombining plasma
components, possibly a sign of shock compression or heating of the interstellar medium by outflowing
material. Assuming a recombining plasma scenario, we further estimate the cooling timescale of this
plasma to be on the order of a few hundred to thousands of years, leading us to speculate that a
sequence of accretion events onto the Galactic Black Hole may be a plausible quasi-continuous energy
source to sustain the observed morphology
This study analyzed transit observations of the Neptune-mass exoplanet GJ 436b taken with the Hubble Space Telescope. The transmission spectrum was found to be featureless, ruling out cloud-free hydrogen-dominated atmosphere models with high significance. The flat transmission spectrum is consistent with either an atmosphere containing high-altitude clouds located at a pressure of around 1 millibar, or a relatively hydrogen-poor atmosphere with 3% hydrogen and helium by mass. Bayesian atmospheric modeling showed that cloudy hydrogen-dominated or high-metallicity hydrogen-poor atmospheres provide the best fits to the data. Further observations are needed to distinguish between these scenarios.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
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Ähnlich wie Astronomy from the Moon: From Exoplanets to Cosmology and Beyond in Visible Light
The extremely high albedo of LTT 9779 b revealed by CHEOPSSérgio Sacani
Optical secondary eclipse measurements of small planets can provide a wealth of information about the reflective properties
of these worlds, but the measurements are particularly challenging to attain because of their relatively shallow depth. If such signals
can be detected and modeled, however, they can provide planetary albedos, thermal characteristics, and information on absorbers in
the upper atmosphere.
Aims. We aim to detect and characterize the optical secondary eclipse of the planet LTT 9779 b using the CHaracterising ExOPlanet
Satellite (CHEOPS) to measure the planetary albedo and search for the signature of atmospheric condensates.
Methods. We observed ten secondary eclipses of the planet with CHEOPS. We carefully analyzed and detrended the light curves using
three independent methods to perform the final astrophysical detrending and eclipse model fitting of the individual and combined light
curves.
Results. Each of our analysis methods yielded statistically similar results, providing a robust detection of the eclipse of LTT 9779 b
with a depth of 115±24 ppm. This surprisingly large depth provides a geometric albedo for the planet of 0.80+0.10
−0.17, consistent with
estimates of radiative-convective models. This value is similar to that of Venus in our own Solar System. When combining the eclipse
from CHEOPS with the measurements from TESS and Spitzer, our global climate models indicate that LTT 9779 b likely has a super
metal-rich atmosphere, with a lower limit of 400× solar being found, and the presence of silicate clouds. The observations also reveal
hints of optical eclipse depth variability, but these have yet to be confirmed.
Conclusions. The results found here in the optical when combined with those in the near-infrared provide the first steps toward
understanding the atmospheric structure and physical processes of ultrahot Neptune worlds that inhabit the Neptune desert.
Parallax is the apparent change in position of an object when viewed from different positions. It can be used to measure distances to celestial objects. Stellar parallax involves measuring the difference in the position of a nearby star observed from opposite sides of Earth's orbit around the Sun. This allows astronomers to determine the star's distance using trigonometry. In 1989, the Hipparcos satellite improved parallax measurements for over 100,000 nearby stars. The Gaia satellite, launched in 2013, can measure parallax angles to greater accuracy, mapping stars up to tens of thousands of light years away.
First results from_the_hubble_opal_program_jupiter_in_2015Sérgio Sacani
Os cientistas usando o Telescópio Espacial Hubble da NASA/ESA produziram novos mapas de Júpiter, que mostram as contínuas mudanças que ocorrem com a famosa Grande Mancha Vermelha. As imagens também revelam uma rara estrutura em forma de onda na atmosfera do planeta que não tinha sido vista por décadas. A nova imagem é a primeira de uma série de retratos anuais dos planetas externos do Sistema Solar, que nos darão um novo olhar desses mundos remotos, e ajudarão os cientistas a estudarem como eles mudam com o passar do tempo.
Nessa nova imagem de Júpiter, uma grande quantidade de feições foi capturada incluindo ventos, nuvens e tempestades. Os cientistas por trás dessas novas imagens, as obtiveram usando a Wide Field Camera 3 do Hubble, num período de observação de mais de 10 horas e produziram assim dois mapas completos do planeta, a partir das suas observações. Esses mapas fizeram com que fosse possível determinar a velocidade dos ventos em Júpiter, com a finalidade de identificar diferentes fenômenos na sua atmosfera além de traquear as suas feições mais famosas.
As novas imagens confirmam que a grande tempestade que tem existido na superfície de nuvens de Júpiter por no mínimo 300 anos, continua a encolher, mas mesmo que desapareça, ela irá morrer lutando. A tempestade, conhecida como Grande Mancha Vermelha, é vista aqui fazendo seus movimentos em espiral no centro da imagem do planeta. Ela tem diminuído de tamanho de maneira muito rápida de ano em ano. Mas agora, a taxa de encolhimento parece ter reduzido novamente, mesmo apesar da mancha ser cerca de 240 quilômetros menor do que era em 2014.
The long period_galactic_cepheid_rs_puppisSérgio Sacani
This document summarizes an observational study that uses light echoes to determine the geometric distance to the Cepheid variable star RS Puppis. Images of RS Puppis and its surrounding nebula were taken over multiple epochs with the ESO NTT telescope to track the progression of light variations within the nebula. Photometric measurements of the phase lag in several nebula regions were used to derive a geometric distance of 1,992 ± 28 parsecs to RS Puppis, one of the most accurate distances yet measured to a Cepheid variable star.
This document provides an outline and overview of key concepts in astronomy related to light and telescopes. It discusses:
1. The electromagnetic spectrum and different types of electromagnetic radiation used in astronomy like visible light, infrared, ultraviolet, X-rays, and radio waves.
2. Optical telescopes and their components like lenses, mirrors, and eyepieces. It also covers concepts like light gathering power, resolving power, and magnification.
3. Modern telescope designs that are lighter, computer-controlled, and use techniques like adaptive optics to improve image quality.
4. Other types of telescopes like radio telescopes and how interferometry is used to improve their resolving power by combining signals from
•Lunar laser telemetry consists in determining the round-trip travel time of the light between a transmitter on the Earth and a reflector on the Moon, which is an equivalent measurement of the distance between these two points
The muse 3_d_view_of_the_hubble_deep_field_southSérgio Sacani
Artigo mostra como foram as observações feitas com o MUSE, o novo instrumento do VLT do campo profundo do Hubble. Além de descobrir 20 novos objetos, o MUSE conseguiu medir as propriedades das galáxias e até representar as mais próximas em 3 dimensões.
Fluorescence detector Array of Single-pixel Telescopes (FAST) projectToshihiro FUJII
This document discusses the history and development of fluorescence detection techniques for ultra-high energy cosmic rays (UHECR). It proposes a new concept called the Fluorescence detector Array of Single-pixel Telescopes (FAST) project. FAST aims to develop an optimized and economical fluorescence detector array to observe UHECRs above 1019.5 eV over a large area. The document outlines the design of FAST stations and reports on an initial test using the EUSO-TA prototype that successfully detected laser pulses and UHECR signals. It concludes by discussing plans to construct a new full-scale FAST prototype and the potential for FAST to increase UHECR exposure and help resolve questions about their origin.
The document summarizes the prospect of UV observations from the Moon using a proposed UV telescope called LUCI. Some key points:
1. LUCI would be a small UV telescope (30cm aperture) to be deployed on the lunar surface by Team Indus, to take advantage of the Moon's stable environment for UV astronomy.
2. The telescope would image bright UV sources like stars and nebulae to magnitudes of 12 to study transients and variability. It would cover 60 square degrees in a lunar day.
3. The design and calibration of LUCI's optics, structure, detectors, and electronics are described, showing it can meet weight and size constraints for deployment on the lunar lander while achieving the
Measurements of the_near_nucleus_coma_of_comet_67_p_churyumov_gerasimenko_wit...Sérgio Sacani
Artigo descreve descoberta feita pelo instrumento Alice da sonda Rosetta no cometa 67P/Churyumov-Gerasimenko, das moléculas de água e dióxido de carbono quebradas que pairam pela atmosfera do cometa.
Spectroscopy and thermal modelling of the first interstellar object 1I/2017 U...Sérgio Sacani
During the formation and evolution of the Solar System, significant
numbers of cometary and asteroidal bodies were
ejected into interstellar space1,2. It is reasonable to expect that
the same happened for planetary systems other than our own.
Detection of such interstellar objects would allow us to probe
the planetesimal formation processes around other stars, possibly
together with the effects of long-term exposure to the
interstellar medium. 1I/2017 U1 ‘Oumuamua is the first known
interstellar object, discovered by the Pan-STARRS1 telescope
in October 2017 (ref. 3). The discovery epoch photometry
implies a highly elongated body with radii of ~ 200 × 20 m
when a comet-like geometric albedo of 0.04 is assumed. The
observable interstellar object population is expected to be
dominated by comet-like bodies in agreement with our spectra,
yet the reported inactivity of 'Oumuamua implies a lack
of surface ice. Here, we report spectroscopic characterization
of ‘Oumuamua, finding it to be variable with time but similar
to organically rich surfaces found in the outer Solar System.
We show that this is consistent with predictions of an insulating
mantle produced by long-term cosmic ray exposure4.
An internal icy composition cannot therefore be ruled out by
the lack of activity, even though ‘Oumuamua passed within
0.25 au of the Sun.
Mapping spiral structure on the far side of the Milky WaySérgio Sacani
Little is known about the portion of the Milky Way lying beyond the Galactic center at distances
of more than 9 kiloparsec from the Sun. These regions are opaque at optical wavelengths
because of absorption by interstellar dust, and distances are very large and hard to measure.
We report a direct trigonometric parallax distance of 20:4þ2:8
2:2 kiloparsec obtained with the Very
Long Baseline Array to a water maser source in a region of active star formation. These
measurements allow us to shed light on Galactic spiral structure by locating the ScutumCentaurus
spiral arm as it passes through the far side of the Milky Way and to validate a
kinematic method for determining distances in this region on the basis of transverse motions.
Spitzer as microlens_parallax_satellite_mass_measurement_for_exoplanet_and_hi...Sérgio Sacani
This document summarizes a study using Spitzer and ground-based observations to measure the microlens parallax vector πE for the first time for a planetary microlensing event, OGLE-2014-BLG-0124L. The πE measurement allows the mass and distance of the planet and its host star to be determined. Spitzer observations provided a 2.5% precision measurement of πE, substantially improving upon the 22% precision from ground data alone. The planet has a mass of about 0.5 Jupiter masses and orbits a star of about 0.7 solar masses at a projected distance of about 3.1 AU.
MAGIA satellite. Experimental Astronomy (8 December 2010), pp. 1-20Stefano Coltellacci
The document describes the MAGIA satellite mission, which aims to study the Moon's internal structure, polar regions, and exosphere. The satellite will carry a suite of instruments including cameras, an altimeter, particle detectors, and accelerometers. It will be launched via Soyuz rocket into a lunar transfer orbit, then enter a polar mapping orbit for 6 months before transitioning to a gravity science orbit. Key challenges include meeting tight budget constraints while achieving ambitious science goals and accommodating multiple payloads and propulsion systems for orbital maneuvers.
No global pluto_like_atmosphere_on_dwarf_planet_makemake_from_a_stellar_occul...Sérgio Sacani
1. A stellar occultation event was observed involving the dwarf planet Makemake on April 23, 2011 using multiple telescopes.
2. Analysis of the light curves from the event showed abrupt disappearances and reappearances of the star, indicating Makemake has no global atmosphere at an upper limit of 4-12 nanobar surface pressure.
3. The occultation data was used to determine Makemake has dimensions of 1,430±9 km by 1,502±45 km, implying a high geometric albedo of 0.77±0.03. This rules out a low density and suggests Makemake is in hydrostatic equilibrium as an oblate spheroid.
This document summarizes a blind HI survey of the southern Milky Way zone of avoidance conducted with the Parkes radio telescope. The survey detected 883 galaxies at Galactic longitudes 212° < l < 36° and latitudes |b| < 5° to a sensitivity of 6 mJy per 27 km/s channel. Fifty-one percent of detections had known optical/near-infrared counterparts, while 27% had new counterparts identified. The survey delineated large-scale structures in the Puppis and Great Attractor regions for the first time. Several newly identified galaxy concentrations and clusters were revealed that help trace the Great Attractor Wall.
The Possible Tidal Demise of Kepler’s First Planetary SystemSérgio Sacani
We present evidence of tidally-driven inspiral in the Kepler-1658 (KOI-4) system, which consists of a giant planet
(1.1RJ, 5.9MJ) orbiting an evolved host star (2.9Re, 1.5Me). Using transit timing measurements from Kepler,
Palomar/WIRC, and TESS, we show that the orbital period of Kepler-1658b appears to be decreasing at a rate = -
+ P 131 22
20 ms yr−1
, corresponding to an infall timescale P P » 2.5 Myr. We consider other explanations for the
data including line-of-sight acceleration and orbital precession, but find them to be implausible. The observed
period derivative implies a tidal quality factor
¢ = ´ -
+ Q 2.50 10 0.62
0.85 4, in good agreement with theoretical
predictions for inertial wave dissipation in subgiant stars. Additionally, while it probably cannot explain the entire
inspiral rate, a small amount of planetary dissipation could naturally explain the deep optical eclipse observed for
the planet via enhanced thermal emission. As the first evolved system with detected inspiral, Kepler-1658 is a new
benchmark for understanding tidal physics at the end of the planetary life cycle
How do engines make a gps for the milky way possibleBurraqITSloution
The Moons project aims to map the Milky Way galaxy in 3D by using a new spectrograph instrument called Moons installed on the Very Large Telescope in Chile. Moons will be able to simultaneously observe the spectra of 1,001 astronomical objects, providing more detailed information about their composition and motion than images alone. This will allow astronomers to see deeper into the galaxy and create the first comprehensive 3D map of the Milky Way, functioning like a "GPS" for navigation within the galaxy. Key to Moons' ability to precisely position its 1,001 optical fibers is the use of high-precision stepper motors and gears from Faulhaber, without which the project would not be possible. Moons is expected to
X-rays from a Central “Exhaust Vent” of the Galactic Center ChimneySérgio Sacani
Using deep archival observations from the Chandra X-ray Observatory, we present an analysis of
linear X-ray-emitting features located within the southern portion of the Galactic center chimney,
and oriented orthogonal to the Galactic plane, centered at coordinates l = 0.08◦
, b = −1.42◦
. The
surface brightness and hardness ratio patterns are suggestive of a cylindrical morphology which may
have been produced by a plasma outflow channel extending from the Galactic center. Our fits of the
feature’s spectra favor a complex two-component model consisting of thermal and recombining plasma
components, possibly a sign of shock compression or heating of the interstellar medium by outflowing
material. Assuming a recombining plasma scenario, we further estimate the cooling timescale of this
plasma to be on the order of a few hundred to thousands of years, leading us to speculate that a
sequence of accretion events onto the Galactic Black Hole may be a plausible quasi-continuous energy
source to sustain the observed morphology
This study analyzed transit observations of the Neptune-mass exoplanet GJ 436b taken with the Hubble Space Telescope. The transmission spectrum was found to be featureless, ruling out cloud-free hydrogen-dominated atmosphere models with high significance. The flat transmission spectrum is consistent with either an atmosphere containing high-altitude clouds located at a pressure of around 1 millibar, or a relatively hydrogen-poor atmosphere with 3% hydrogen and helium by mass. Bayesian atmospheric modeling showed that cloudy hydrogen-dominated or high-metallicity hydrogen-poor atmospheres provide the best fits to the data. Further observations are needed to distinguish between these scenarios.
Ähnlich wie Astronomy from the Moon: From Exoplanets to Cosmology and Beyond in Visible Light (20)
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the
atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets
receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric
composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet
transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days.
The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We
confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and
validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as
well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope
and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host
star is inactive, with an X-ray-to-bolometric luminosity ratio of log 5.7 L L X bol » - . Joint analysis of the light
curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕,a3σ mass upper limit of
3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric
(TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small
list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a
bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the
lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors
42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations
with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory,
as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of
12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent
future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar
compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool
stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Sérgio Sacani
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary
system with negligible binary interaction following black-hole formation. The black-hole mass (≈10M⊙)
and near-circular orbit (e ≈ 0.02) of VFTS 243 suggest that the progenitor star experienced complete
collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to
constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence
level, the natal kick velocity (mass decrement) is ≲10 km=s (≲1.0M⊙), with a full probability distribution
that peaks when ≈0.3M⊙ were ejected, presumably in neutrinos, and the black hole experienced a natal
kick of 4 km=s. The neutrino-emission asymmetry is ≲4%, with best fit values of ∼0–0.2%. Such a small
neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.
Detectability of Solar Panels as a TechnosignatureSérgio Sacani
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
Jet reorientation in central galaxies of clusters and groups: insights from V...Sérgio Sacani
Recent observations of galaxy clusters and groups with misalignments between their central AGN jets
and X-ray cavities, or with multiple misaligned cavities, have raised concerns about the jet – bubble
connection in cooling cores, and the processes responsible for jet realignment. To investigate the
frequency and causes of such misalignments, we construct a sample of 16 cool core galaxy clusters and
groups. Using VLBA radio data we measure the parsec-scale position angle of the jets, and compare
it with the position angle of the X-ray cavities detected in Chandra data. Using the overall sample
and selected subsets, we consistently find that there is a 30% – 38% chance to find a misalignment
larger than ∆Ψ = 45◦ when observing a cluster/group with a detected jet and at least one cavity. We
determine that projection may account for an apparently large ∆Ψ only in a fraction of objects (∼35%),
and given that gas dynamical disturbances (as sloshing) are found in both aligned and misaligned
systems, we exclude environmental perturbation as the main driver of cavity – jet misalignment.
Moreover, we find that large misalignments (up to ∼ 90◦
) are favored over smaller ones (45◦ ≤ ∆Ψ ≤
70◦
), and that the change in jet direction can occur on timescales between one and a few tens of Myr.
We conclude that misalignments are more likely related to actual reorientation of the jet axis, and we
discuss several engine-based mechanisms that may cause these dramatic changes.
The solar dynamo begins near the surfaceSérgio Sacani
The magnetic dynamo cycle of the Sun features a distinct pattern: a propagating
region of sunspot emergence appears around 30° latitude and vanishes near the
equator every 11 years (ref. 1). Moreover, longitudinal flows called torsional oscillations
closely shadow sunspot migration, undoubtedly sharing a common cause2. Contrary
to theories suggesting deep origins of these phenomena, helioseismology pinpoints
low-latitude torsional oscillations to the outer 5–10% of the Sun, the near-surface
shear layer3,4. Within this zone, inwardly increasing differential rotation coupled with
a poloidal magnetic field strongly implicates the magneto-rotational instability5,6,
prominent in accretion-disk theory and observed in laboratory experiments7.
Together, these two facts prompt the general question: whether the solar dynamo is
possibly a near-surface instability. Here we report strong affirmative evidence in stark
contrast to traditional models8 focusing on the deeper tachocline. Simple analytic
estimates show that the near-surface magneto-rotational instability better explains
the spatiotemporal scales of the torsional oscillations and inferred subsurface
magnetic field amplitudes9. State-of-the-art numerical simulations corroborate these
estimates and reproduce hemispherical magnetic current helicity laws10. The dynamo
resulting from a well-understood near-surface phenomenon improves prospects
for accurate predictions of full magnetic cycles and space weather, affecting the
electromagnetic infrastructure of Earth.
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...Sérgio Sacani
In the Nice model of solar system formation, Uranus and Neptune undergo an orbital upheaval,
sweeping through a planetesimal disk. The region of the disk from which material is accreted by
the ice giants during this phase of their evolution has not previously been identified. We perform
direct N-body orbital simulations of the four giant planets to determine the amount and origin of solid
accretion during this orbital upheaval. We find that the ice giants undergo an extreme bombardment
event, with collision rates as much as ∼3 per hour assuming km-sized planetesimals, increasing the
total planet mass by up to ∼0.35%. In all cases, the initially outermost ice giant experiences the
largest total enhancement. We determine that for some plausible planetesimal properties, the resulting
atmospheric enrichment could potentially produce sufficient latent heat to alter the planetary cooling
timescale according to existing models. Our findings suggest that substantial accretion during this
phase of planetary evolution may have been sufficient to impact the atmospheric composition and
thermal evolution of the ice giants, motivating future work on the fate of deposited solid material.
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Sérgio Sacani
The highest priority recommendation of the Astro2020 Decadal Survey for space-based astronomy
was the construction of an observatory capable of characterizing habitable worlds. In this paper series
we explore the detectability of and interference from exomoons and exorings serendipitously observed
with the proposed Habitable Worlds Observatory (HWO) as it seeks to characterize exoplanets, starting
in this manuscript with Earth-Moon analog mutual events. Unlike transits, which only occur in systems
viewed near edge-on, shadow (i.e., solar eclipse) and lunar eclipse mutual events occur in almost every
star-planet-moon system. The cadence of these events can vary widely from ∼yearly to multiple events
per day, as was the case in our younger Earth-Moon system. Leveraging previous space-based (EPOXI)
lightcurves of a Moon transit and performance predictions from the LUVOIR-B concept, we derive
the detectability of Moon analogs with HWO. We determine that Earth-Moon analogs are detectable
with observation of ∼2-20 mutual events for systems within 10 pc, and larger moons should remain
detectable out to 20 pc. We explore the extent to which exomoon mutual events can mimic planet
features and weather. We find that HWO wavelength coverage in the near-IR, specifically in the 1.4 µm
water band where large moons can outshine their host planet, will aid in differentiating exomoon signals
from exoplanet variability. Finally, we predict that exomoons formed through collision processes akin
to our Moon are more likely to be detected in younger systems, where shorter orbital periods and
favorable geometry enhance the probability and frequency of mutual events.
Emergent ribozyme behaviors in oxychlorine brines indicate a unique niche for...Sérgio Sacani
Mars is a particularly attractive candidate among known astronomical objects
to potentially host life. Results from space exploration missions have provided
insights into Martian geochemistry that indicate oxychlorine species, particularly perchlorate, are ubiquitous features of the Martian geochemical landscape. Perchlorate presents potential obstacles for known forms of life due to
its toxicity. However, it can also provide potential benefits, such as producing
brines by deliquescence, like those thought to exist on present-day Mars. Here
we show perchlorate brines support folding and catalysis of functional RNAs,
while inactivating representative protein enzymes. Additionally, we show
perchlorate and other oxychlorine species enable ribozyme functions,
including homeostasis-like regulatory behavior and ribozyme-catalyzed
chlorination of organic molecules. We suggest nucleic acids are uniquely wellsuited to hypersaline Martian environments. Furthermore, Martian near- or
subsurface oxychlorine brines, and brines found in potential lifeforms, could
provide a unique niche for biomolecular evolution.
Continuum emission from within the plunging region of black hole discsSérgio Sacani
The thermal continuum emission observed from accreting black holes across X-ray bands has the potential to be leveraged as a
powerful probe of the mass and spin of the central black hole. The vast majority of existing ‘continuum fitting’ models neglect
emission sourced at and within the innermost stable circular orbit (ISCO) of the black hole. Numerical simulations, however,
find non-zero emission sourced from these regions. In this work, we extend existing techniques by including the emission
sourced from within the plunging region, utilizing new analytical models that reproduce the properties of numerical accretion
simulations. We show that in general the neglected intra-ISCO emission produces a hot-and-small quasi-blackbody component,
but can also produce a weak power-law tail for more extreme parameter regions. A similar hot-and-small blackbody component
has been added in by hand in an ad hoc manner to previous analyses of X-ray binary spectra. We show that the X-ray spectrum
of MAXI J1820+070 in a soft-state outburst is extremely well described by a full Kerr black hole disc, while conventional
models that neglect intra-ISCO emission are unable to reproduce the data. We believe this represents the first robust detection of
intra-ISCO emission in the literature, and allows additional constraints to be placed on the MAXI J1820 + 070 black hole spin
which must be low a• < 0.5 to allow a detectable intra-ISCO region. Emission from within the ISCO is the dominant emission
component in the MAXI J1820 + 070 spectrum between 6 and 10 keV, highlighting the necessity of including this region. Our
continuum fitting model is made publicly available.
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...Advanced-Concepts-Team
Presentation in the Science Coffee of the Advanced Concepts Team of the European Space Agency on the 07.06.2024.
Speaker: Diego Blas (IFAE/ICREA)
Title: Gravitational wave detection with orbital motion of Moon and artificial
Abstract:
In this talk I will describe some recent ideas to find gravitational waves from supermassive black holes or of primordial origin by studying their secular effect on the orbital motion of the Moon or satellites that are laser ranged.
Authoring a personal GPT for your research and practice: How we created the Q...Leonel Morgado
Thematic analysis in qualitative research is a time-consuming and systematic task, typically done using teams. Team members must ground their activities on common understandings of the major concepts underlying the thematic analysis, and define criteria for its development. However, conceptual misunderstandings, equivocations, and lack of adherence to criteria are challenges to the quality and speed of this process. Given the distributed and uncertain nature of this process, we wondered if the tasks in thematic analysis could be supported by readily available artificial intelligence chatbots. Our early efforts point to potential benefits: not just saving time in the coding process but better adherence to criteria and grounding, by increasing triangulation between humans and artificial intelligence. This tutorial will provide a description and demonstration of the process we followed, as two academic researchers, to develop a custom ChatGPT to assist with qualitative coding in the thematic data analysis process of immersive learning accounts in a survey of the academic literature: QUAL-E Immersive Learning Thematic Analysis Helper. In the hands-on time, participants will try out QUAL-E and develop their ideas for their own qualitative coding ChatGPT. Participants that have the paid ChatGPT Plus subscription can create a draft of their assistants. The organizers will provide course materials and slide deck that participants will be able to utilize to continue development of their custom GPT. The paid subscription to ChatGPT Plus is not required to participate in this workshop, just for trying out personal GPTs during it.
The technology uses reclaimed CO₂ as the dyeing medium in a closed loop process. When pressurized, CO₂ becomes supercritical (SC-CO₂). In this state CO₂ has a very high solvent power, allowing the dye to dissolve easily.
Immersive Learning That Works: Research Grounding and Paths ForwardLeonel Morgado
We will metaverse into the essence of immersive learning, into its three dimensions and conceptual models. This approach encompasses elements from teaching methodologies to social involvement, through organizational concerns and technologies. Challenging the perception of learning as knowledge transfer, we introduce a 'Uses, Practices & Strategies' model operationalized by the 'Immersive Learning Brain' and ‘Immersion Cube’ frameworks. This approach offers a comprehensive guide through the intricacies of immersive educational experiences and spotlighting research frontiers, along the immersion dimensions of system, narrative, and agency. Our discourse extends to stakeholders beyond the academic sphere, addressing the interests of technologists, instructional designers, and policymakers. We span various contexts, from formal education to organizational transformation to the new horizon of an AI-pervasive society. This keynote aims to unite the iLRN community in a collaborative journey towards a future where immersive learning research and practice coalesce, paving the way for innovative educational research and practice landscapes.
(June 12, 2024) Webinar: Development of PET theranostics targeting the molecu...Scintica Instrumentation
Targeting Hsp90 and its pathogen Orthologs with Tethered Inhibitors as a Diagnostic and Therapeutic Strategy for cancer and infectious diseases with Dr. Timothy Haystead.
Describing and Interpreting an Immersive Learning Case with the Immersion Cub...Leonel Morgado
Current descriptions of immersive learning cases are often difficult or impossible to compare. This is due to a myriad of different options on what details to include, which aspects are relevant, and on the descriptive approaches employed. Also, these aspects often combine very specific details with more general guidelines or indicate intents and rationales without clarifying their implementation. In this paper we provide a method to describe immersive learning cases that is structured to enable comparisons, yet flexible enough to allow researchers and practitioners to decide which aspects to include. This method leverages a taxonomy that classifies educational aspects at three levels (uses, practices, and strategies) and then utilizes two frameworks, the Immersive Learning Brain and the Immersion Cube, to enable a structured description and interpretation of immersive learning cases. The method is then demonstrated on a published immersive learning case on training for wind turbine maintenance using virtual reality. Applying the method results in a structured artifact, the Immersive Learning Case Sheet, that tags the case with its proximal uses, practices, and strategies, and refines the free text case description to ensure that matching details are included. This contribution is thus a case description method in support of future comparative research of immersive learning cases. We then discuss how the resulting description and interpretation can be leveraged to change immersion learning cases, by enriching them (considering low-effort changes or additions) or innovating (exploring more challenging avenues of transformation). The method holds significant promise to support better-grounded research in immersive learning.
hematic appreciation test is a psychological assessment tool used to measure an individual's appreciation and understanding of specific themes or topics. This test helps to evaluate an individual's ability to connect different ideas and concepts within a given theme, as well as their overall comprehension and interpretation skills. The results of the test can provide valuable insights into an individual's cognitive abilities, creativity, and critical thinking skills
Astronomy from the Moon: From Exoplanets to Cosmology and Beyond in Visible Light
1. Phil. Trans. R. Soc. A.
doi:10.1098/not yet assigned
Astronomy from the Moon: From Exoplanets to Cosmology and Beyond in Visible Light
Jean Schneider and Antoine Labeyrie
Insert
affiliations here, include: Department, Institution, Address, City, Area and Code,
Country, ORCID ID"
Keywords: solar system - exoplanets - stellar physics – cosmology - quantum
physics
Abstract
We review what could be astronomy from the Moon in the next decades in the visible domain.
After a short review observational approaches, from photometry to high contrast and high angular
resolution imaging, We essentially focus on some promising scientific objectives, from Solar
System to the extragalactic domain. At the end, I add a proposal to use the Earth-Moon system to
test fundamental physics. Since this meeting is dedicated to the next decades of Astronomy from
the Moon, we consider projects and science objectives for several decades from now.
1. Introduction
The Moon offers exceptional conditions for astronomy since it accumulates the advantages of
ground based and space based observational conditions. Without atmosphere, it has the same sky
quality than telescopes on satellites and access to all wavelengths. It will also permit the same
Jean Schneider (jean.schneider@obspm.fr)
Paris Observatory, Luth UMR 8102, Meudon, 92190, France
ORCID 0000-0002-3136-6537
Antoine Labeyrie (anlabeyrie@orange.fr)
Observatoire de La Côte d’Azue, Nice, 06000 , France
2. upgrade and reparation possibilities than on Earth. In addition, lunar observatories offer
conditions which are specific to the Moon: 1/ since the Moon rotates 28 slower than Earth, it
permits longer observations of an object than ground based telescopes 2/ since they see the sky
through an angle different than the view from Earth, they allow some observations impossible
from Earth. Another advantage of lunar telescopes compared to space telescopes is that the latter
have a limited lifetime due to fuel consumption, although there are projects to refurbish
spacecrafts with spatializes fuel tankers1
Here we restrict ourselves to optical astronomy in the
visible wavelengths, infrared astronomy being discussed by Maillard (2023 ALLURE project [1]).
In section 2 we list instrumental approaches: spectrophotometry, spectropolarimetry and
interferometry. In section 3 we review the main logistic issues. In section 4 we provide a, non
exhaustive, sometimes nonstandard, panorama of science objectives, in the spirit of [2]. Finally, in
section 5 we propose a 1-5 meter telescope as a common precursor of different large projects.
2. Instrumental approaches
2.1 Spectro-photometry and spectro-polarimetry
A priori, any telescope can make both of them. The 1,000 m2
array of 6.5 m telescopes at the
lunar pole (Life Finder Telescope At Lunar Poles LFTALP) project is an array dedicated to
transits [3]. It is a lunar extension of the ground-based LFAST project (Large Fiber Array
Spectroscopic Telescope [4]). The LOUVE project (Lunar Optical UV Explorer - [5]) is a 30 cm
project to take advantage of the absence of lunar atmosphere to make spectrophotometry of bright
sources in the UV.
2.2 Direct imaging
2.2.1 Moderate size telescopes. As presented in this issue, the Loupe telescope is
a one meter class telescope devoted to observe the Earth ([6], |7]). In the section 4
we extend its original goal to other scientific purposes.
2.2.2 Large telescopes
Large telescopes provide both high angular resolution and photometric sensitivity.
They present less difficulty to manoeuvre than large terrestrial telescopes since the
lunar gravity is smaller than on Earth and there is no wind on the Moon. Theble:
OWL-Moon project is a 50 or more meter class proposed telescope |8] equipped
with a coronagraph for very high contrast imaging with multiple sciences cases,
from exoplanets to cosmology.
2.3 Very high angular resolution
2.3.1 Standard interferometer
1For instance the Orbit Fab company is preparing tanker refuelling mission :
https://www.orbitfab.com/
3. A standard interferometer project, similar to the Gravity interferometer at the
european VLT [9] has recently been proposed for the Moon [10]. It could have a
several kilometre baseline. Since with its 28 days orbit around the Earth and its
locked orbit the Moon rotates more slowly than Earth, for a given observation time
the delay lines must be 28 times shorter than for a ground based telescope.
2.3.2 Hypertelescope
A hypertelescope is a 2D array with many sub-pupill mirrors where, at the
recombined focus, there is a “pupill densifier” which directly provides 2D images
instead of complicated fringed images for extended sources. One introduces a FOV
limitation, that does not depend on the geometry of the array but only on the beam
combination scheme. This field is referred to as Direct Imaging FOV (DIF), that is,
the FOV inside which an image of a source can be formed directly [36]. If s is the
spacing of two adjacent mirrors (assume larger than the mirror sizes), the “Direct
Imaging FOV” (DIF) angular size θDIF = λ/s and diameter of the interference
peak θpeak= λ/D imply that the DIF can contain a grid of nr = (D/s)2
= N adjacent
resolution elements (resels) . But the residual halos surrounding the interference
peak in the image of each point source become incoherently added in the image,
thus degrading the image contrast. If the DIF size is configured to match that of the
planet's image, thus containing N resels, the resulting halo level grows as N and
therefore reaches that of the interference peaks. Deconvolution techniques such as
modified for hypertelescopic images are more efficient and can even reconstruct
sources located beyond the DIF, while still in the Fizeau envelope [11]. A ground-
based demonstrator is under construction in the south of France [34]. On the Moon,
the array may be a classical interferometer with delay lines to compensate the
Moon rotation. Due to the slow orbital revolution of the Moon around the Earth
compared to the 24 hour Earth rotation, for a 3 hour observation 1 meter delay
lines are sufficient, compared to 30 meters delay lines at the VLTI. To avoid delay
lines, the mirrors could be installed on a paraboloid in a lunar crater (Figure 1).
The pixels on a 2D objects have, at a wavelength λ , an angular resolution
λ/s where s is the spacing of sub-pupills.
4. Figure 1 Sketch at approximate scale of a Crater-Nested Lunar Hypertelescope with its focal
receiver suspended from cables and movable along the focal surface (fine dotted arc). The locus
of the mirror array (fat dotted arc) is either paraboloidal actively deformable by applying small
tip-tilt piston corrections on its segments, or fixed and spherical if a corrector of spherical
aberration is added in the focal optics. No delay lines are needed but the “meta-mirror” size is
limited to about 20 km by the maximal 6 km depth of impact craters for an effective meta-
aperture of 5–10 km. The mirror elements are either carried by separate fixed tripods or by a
hammock-like cable netting. The figure at right shows how the focal instruments can be moved to
follow the target or go to another target [12].
Another solution would be to attach the small mirrors to the crater cliff, with focal
instruments on the opposite point of the cliff summit (Figure 2). It would avoid yje
need for a long cable carrying the focal instruments, but the pointing range
visibility would be very limited.
Figure 2 Hypertelescope with mirrors on a cliff of the crater
2.3.3 Intensity Interferometry
Intensity interferometry [35], with two telescopes measures the factor |γ 12|
defined by
<Δ I1(t ,r1)Δ I2(t ,r2)>=(<I (r1,t)>< I (r2 ,)>)(1+|γ12|
2
) (1)
5. where γ12 is the mutual coherence function of light between locations r1 and r2
and < > means the time average. For three telescopes The relation becomes
<Δ I1(t ,r1)Δ I2(t ,r2)Δ I3(t ,r3)>=(< I (r1,t)>< I(r2 ,t)><I (r3 ,t)>).(1+| γ12|
2
| γ23|
2
| γ31|
2
+2ℜ(γ12 γ23 γ31))
etc for N telescopes [13].
For two telescopes, the signal to noise ratio is
(S/N)RM S=A·α ·n·γ12(r)
2
·Δ f
1/2
·(T /2)
1/2
(2)
where A is the geometric mean of the areas (not diameters) of the two
telescopes, α is the quantum efficiency of the optics plus detector system, n is
the flux of the source in photons per unit optical bandwidth per unit area per
unit time; ∆f is the bandwidth of the detector and T is the integration time [13].
The correlation leads to an angular resolution up to λ /L for a wavelength λ
and a baseline L. But, to achieve a S/N ratio of 3, the relation (2) shows that it
requires a very narrow wave band with a very fast (pico to femto second time
resolution) detector and a large number of collected photons to reach a 3 sigma
SNR. A large collecting area is thus required. A 50 meter OWL-Moon like
telescope on the Moon and some 30-40 meter class ground-based telescopes are
suited for that purpose. For N telescopes with non-redundant baselines, the number
of baselines is N(N-1)/2. A large number of baselines allows for the construction of
2D images of extended objects with an angular resolution λ/L where L is the
mean separation of two telescopes. For an Earth-Moon intensity interferometer one
can combine all future lunar optical telescopes, in particular the 1,000 m2
array of
6.5 m telescopes at the lunar pole [3] and ground optical telescopes and the
multiplication of baselines provided by the Earth orbit around the Sun and the
Moon orbit around the Earth to explore the (u, v) Fourier transform plane. In
addition to a few very large ground telescopes, it has been proposed to use the
collaboration of many amateur ground telescopes [14]. They would add terrestrial
baselines and contribute to the total collecting area A used in the formula (2).
3. Issues
3.1 Dust
There are and will be two main sources of lunar dust, meteoritic impacts and
human activities. They will essentially degrade the reflectivity or transparency of
optical surfaces. Several projects intend to measure its properties, e.g. [15] It is
thus important to take countermeasures to eliminate its impacts on instrumentation.
For instance, electromagnetic removal has been proposed [16].
3.2 Lunar seismology
6. As analysed in [17], the seismic activity of the Moon may be an issue for lunar
interferometers. But, as noted by the authors, a “Moon-based version could be
considered in the long term when a human presence would permit maintenance
and upgrading leading to a longer lifetime with continuous performance
enhancement”. Indeed, in the long term humans will be able to equip
interferometers with acoustic filters, similarly to what is done for terrestrial
gravitational wave detectors. There is thus no show stop here.
3.3 Location
The best location of a lunar telescope depends on two factors: the physical
conditions of the location (temperature, soil quality, solar illumination) and and
and its scientific objectives. For instances, telescopes looking in the Earth direction
have to be located on the near side of the Moon. From the point of view of target
observability they can be placed almost anywhere. At the lunar poles, only half the
sky is visible, but all the time. At the lunar equator, all sky is visible, but only half
time.
For LOUPE the optimum is not far from the lunar equator. For LOUVE, three
possible possible locations can be considered on the two lunar north and southern
hemispheres and near the equator since it should be a mow-cost telescope.
4. Main Science Objectives
4.1 Solar System
4.1.1 Observations towards the Earth
4.1.1.1 Observations of the Earth itself
The Loupe project is intended to observe the Earth as en exoplanet |6], [7]. It
will in particular determine its polarimetric properties as a function of the phase
angle of the reflected Sun light along its orbit around the Sun. In section 4.1.1.2
another application is described.
EUSO (Extreme Universe Space Observatory) will detect the cosmic ray
showers in the Earth atmosphere from balloons and circum-terrestrial satellites
[18] (Figure 3). A lunar EUSO will have a more global view than satellite-
based EUSOs
7. Figure 3 Different versions of a balloon or in-orbit EUSO. Available at the
EUSO website https://www.jemeuso.org/missions/overview/
4.1.1.2 Solar eclipses
As seen from the Moon, the Earth is 3.8 times as large than the Sun and than
the Moon as seen from the Earth. Therefore, solar eclipses of the Sun by the
Earth as seen from the Moon last 3.8 times longer than solar eclipses by the
Moon as seen from the Earth and will see the far outer regions of the solar
corona (Figure 4).
In addition, it provides a way to probe the whole Earth atmosphere by
transmission spectroscopy of the Sun during the ingress and egress of the
eclipses. And, while Soho and Parker will have a limited lifetime, a lunar
telescope will have a longer lifetime and looking at the Sun will provide long
term observations.
8. Figure 4 Solar far corona seen from the Moon during a solar eclipse by the Earth
4.1.1.3 Stellar observations through Earth’s atmosphere
When a star is on the line joining a lunar telescope to the center of Earth or
very close to it, the Earth atmosphere acts as Earth-sized converging lens [19].
The light rays coming from the star are refracted under different angles,
depending on their wave length and the altitude of their path in the Earth
atmosphere. Some will exactly converge at the Moon surface (Figure 5),
leading to a magnification up to 50,000 |19]. This type of lens is not suited to
imaging, but, its magnification can make it helpful for the photometric
detection of very faint optical sources. For instance, with the help of a high
speed photometer it can detect new optical pulsars. In addition, the
spectroscopic monitoring of these stellar observations will allow to follow the
modifications of the terrestrial atmosphere with meteorology, seasons and solar
eruptions for instance.
Figure 5 Stellar image seen on the Moon through the global Earth atmosphere as a lense.
4.1.1.4 Sun + Earth gravitational deviation
According to General Relativity, a light ray passing at a distance r from an
object of mass M is deviated by an angle α=GM /rc2
=RScharz /r ( RScharz is
the Schwarzschild radius of the object).
9. Since the solar eclipses last 3.8 longer as seen from Earth, and since stellar
positions seen from the Moon will not suffer from atmospheric perturbations,
the precision of measurements will be better than from Earth.
A light ray passing at 2 solar radii from the Sun is deviated by an angle αSul
= 0.5 arcsec. A light ray passing at 1.05 Earth radius from the Earth is deviated
by an angle α Earth = 0.3 mas. A 0.1 mas angular precision is achieved at 0.5
micron by a 25 meter lunar telescope, which would therefore detect from the
Moon the gravitational deflection of a star by the Earth at a 3 sigma level. If, as
seen from the Moon, the Earth is approximately close to the Sun (or even
eclipsing the Sun), the two deviations add (when the star is seen on the same
side of the Sun and the Earth) or subtract themselves (when the star is seen
from the Moon between the Earth and the Sun). Since General relativity is a
non linear theory, the two deviation will only add in first order. The Post
Newtonian formalism adds an additional term O( αSun α Earth ) to the linear
theory. Since the Einstein theory of the two-body Earth-Sun system is not
linear, the global deviation will not be the sum αSun+α Earth
4.1.2 .Stellar occultation by solar systems objects.
Such occultations, if observed from the Moon will generally not be also
observable from Earth. And thanks to the fact that Moon’s rotation is 28 times
longer than Earth’s, stellar occultation could last 28 times longer than seen
from the Earth, depending on the Moon-asteroid-occulted star configuration.
Unfortunately, the probability that the occultation by a given object of the same
star seen from Earth and, before or later, from the Moon is only
(REarth /DEM )
2
=2.10
−4
where REarth and DEM are the Earth radius and
the Earth-Moon distance.
4.2 Exoplanets
4.2.1 Transits light curves and spectroscopy
The 1200 m2 array project at the lunar pole [3] and an OWL-Moon like 50-meter
telescope [8] will make precise measurements of planet radii, Transit Time
Variations (leading to the detection of additional planets and of exo-moons) and
search for the chemical composition of exoplanet atmospheres, potentially
providing biosignatures.
4.2.2 Microlensing Detection
With a lunar telescope one can make coordinated Earth-Moon parallax
observations. Gravitational microlensing generates a circular “Einstein ring” when
the background source is exactly aligned with a circular foreground lens. If the
10. foreground lens is a binary point system, the Einstein ring becomes a non circular
caustics. The background source has a maximum amplification when its line-of-
sight as seen from the Earth crosses the caustics. When the background star is seen
from outside of Earth, it crosses the caustics at different times. This has been
observed with the Spitzer space telescope for OGLE-2016-BLG-1093Lb (Figure 6 -
[20]). Since from the Moon the microlensing event is seen under an angle different
from Earth, it will provide a better 2D characterization of the planet location
respective to its parent star.
Figure 6 Coordinated Earth-Spitzer
microlensing parallax for OGLE-2016-
BLG-1093Lb [20].
4.2.3 Direct imaging
4.2.2.1 Standard
angular resolution
Figure 6 Coordinated Earth-Spitzer microlensing parallax for OGLE-2016-BLG-1093Lb
[20].
A 50 meter OWL-Moon like telescope will provide the detection and make
spectroscopic observations of 300-500 Earth-like planets in 20 years [8]. The
11. follow-up of the planet observations will provide the 3D planet orbits and
seasonal effects.
4.2.2.2 Very high angular resolution
The multipixel observation of exoplanet’s morphology has already been
described in [12]. Here we add other sciences cases.
4.2.2.2.1 Specular reflection of oceans
McCullough [32] and Williams & Gaidos [33] have proposed to detect the
specular reflection of the parent star on oceans of exoplanets (Figure 7). For
example, the glint of terrestrial oceans has been detected with the LCROSS
mission [21]. The follow-up along the planet rotation of the specular reflection
will help to shape the non-reflective parts of the planets, that is their continents.
Figure 7 Simulation of the solar glint by Earth ocean [60]
4.2.2.2.2 Very high resolution imaging of transits
The spectro-imaging of planetary transits of transits can be made with a
hyptertelescope. If RΔ is the spatial resolution on the stellar surface, one
gains a factor R* /RΔ in the SNR compared to transits seen without
resolving the stellar surface, where R* is the stellar radius (Figure 8).
12. Figure 8 Multipixel imaging of planetary transits
Exo-rings and exo-moons can also be detected with Intensity Interferometry
(Figure 9 ).
Figure 9 Simulation of transits of a giant planet with rings and moons seen
by a 2 km intensity interferometry array [13].
13. 4.2.2.2.3 Mountains and volcanoes on planets
Let us go further about very high resolution imaging. Whereas
several of the above science topics can be addressed with a
single OWL on the Moon, some questions require the
extremely high angular resolution afforded by an Earth–Moon
Intensity Interferometer. Once an OWL-type telescope is
installed on the Moon, or even a 10 m lunar precursor, one could
readily address optical Intensity Interferometry with
unprecedented baselines and angular resolution. For instance
it could measure the heights of mountains on transiting
exoplanets. This is an important problem for the geophysics of
planets. Weisskopf [22] has shown that there is a relationship
between the maximum height of mountains on a planet and
its mass and the mechanical characteristics of its crust. The
issue of the detectability of the mountains has already been
addressed for transiting planets [23]. Here we propose a
significant improvement, based on the principle of the
detection of the silhouette of ringed planets by Intensity
Interferometry as developed in [19]. With a 60 m resolution at
the 1.4 pc distance of alpha Cen, for transiting planets,
mountains, down to 500 meter height, will appear at the
border of the planet silhouette during the transit (in case of a
transparent atmosphere with no clouds). These observations
will require very long exposures. During the exposure, the
planet is rotating around its axis, leading to a washing-out of
the features that we are looking at. But the planet rotation
period will be well known from the periodicity of its
photometric data [6]. Therefore, the mountain silhouette will
appear in a two-dimensional Fourier transform of a long
series of short exposure images at the planet rotation
frequency. Moreover, volcanoes, generally associated with
high mountains, can be detected as a temporary excess of red
emission of the planet.
4.3 Stellar physics
14. 4.3.1 Pulsar pulse echoes
Pulsars are generally surrounded by a nebula, gaseous and/or dusty. We
propose to detect the optical echo of the pulse on nearby opaque clumps of
the nebulae with a high speed high angular resolution. The time delay
between the direct pulse and its echoes give the 3D geometry of the
configuration. For the Crab pulsar at 2.5 kpc, with a visible
magnitude 17, assuming clumps at 10 AU from the pulsar
with a 10% reflectivity, and a size 1 AU, the echoes would
have a magnitude m=17−2.5log10 (1/(10∗2π))=22 , still
detectable with a large telescope.
4.3.2 Stellar gravitational lensing
When two stars are on the same line of sight, the foreground star acts as a
gravitational lens on the background star, leading to an ring-like image of the
background star (Einstein ring) with a radius RE=√RSchwarz DS DL/ DLS ,
where RSchwarz is the foreground star Schwarzschild radius, DS and DL the
source and lens distances and DSL the lens-source distance, and a surface
brightness equal to that of the background star. If its angular size is larger than
the foreground star, one can mask the foreground star by a coronagraph and see
only the Einstein ring. If the two stars are not exactly on the same line of sight,
the Einstein ring breaks into two arcs (see Figure 11). For instance, the Einstein
ring of a star at 8 kpc, lensed by a 1 M star at 6 pc has a radius of 70µas |
⊙
24]. See the Figure 10.
Figure 10 Simulation of the Einstein ring of a star at 8 kpc, lensed by a 1 M star at 6 pc. The
⊙
foreground star is occulted by a coronagraph. The radius of the Einstein ring is 70µas [24]
15. 4.4 Extragalactic domain
4.4.1 Gravitational lensing of quasars.
Very high angular resolution gives access to very detailed images, for example in
the case of quasar microlensing. When a background quasar is slightly off the
galaxy line of sight, its Einstein ring breaks into a larger and a smaller arc. The
figure 11 shows the configuration for the Double Quasar 0957+561 (mV = 17).
Very high resolution images will measure the length and width of these arc, and
their curvature will constrain the shape of the lensing galaxy.
Figure 11 Geometry of a lensed quasar, adapted from [25] for the double quasar QSO 0957+561.
RS and DS are the radius and the distance of the quasar source, ML and DL are the mass and the
distance of the lensing galaxy. The figure is not on scale, and the lens galaxy is supposed to be
spherical.
4.4.2 Dark matter distribution
Einstein rings can be disrupted by anomalies in dark matter distribution in the case
where dark matter is made of axions, beyond the standard particle model [26]
(Figure 12).
16. Figure 12 Left: Einstein ring in case of dark matter distributed smoothly in Weakly Interacting
Massive ParticleS (WIMPS). Right: Einstein ring modulated by fluctuations in dark matter
distribution (after [26]).
4.5 Quantum Physics
In the quantum mechanical theory of observation, the problem is the following. The
quantum entanglement between pairs of photons (correlations of photon polarisation)
can, theoretically, go up to infinity. It has been proposed to test this statement for
Earth-Moon distances ([27], [28]): the two photon detectors would be placed one on
Earth and the other on the on the Moon. Recently a variant implementation has been
proposed [29]. The source of photons pairs would be at the Earth-Sun L4 or L5
Lagrange point and one detector on the Earth and the other on the Moon (Figure 13).
Actually, both experiments should be implemented since, given our ignorance of what
could be beyond standard quantum mechanics, one does not know if a variation of
entanglement with distance depends on the length of photon passes or on the distance
between detectors.
Figure 13 A source of entangled photons pairs at the Earth-Sun L4 or L5 Lagrange point
and one detector on the Earth and the other on the Moon [29].
17. One may wonder if there can be a priori theoretical estimates for a distance scale D
or a speed of propagation V of non standard correlations. Playing only with the
usual fundamental constants h, c and G can only give V = c or V = ∞ and D =
Planck length 10-33 cm. Playing in addition with less fundamental constants like
the quark mass Mquark allows to multiply these values by any arbitrary power N of
the dimensionless constant G Mquark
2
/hc ~ 10-39
. For small values of N like -1 or
+1 one gets V = 10+/-39
c and D = 10-33/+39
cm. Another source of a priori estimates
for the distance scale D could come from possible non standard theories or
phenomena like short-scale « fifth » force (D= a few cm to a few meter), the
MOND theory as an alternative theory to dark matter (D ~ 10kpc, [30]), the
Pioneer Anomaly (D ~ 10 AU) or the distance D = cT = 100 kpc derived from the
time scale T = 108 yr for the « spontaneous collapse» [31]. As one can see, the
span of possible a priori predictions has no solid constraint and only experiment
may eventually provide a constraint.
5 A precursor
Among the several facilities described in this meeting, some of them could have a
common one to few meter-class telescope precursor with different focal detectors, from
UV to infrared, in order to explore the different logistic problems. These are LOUVE,
LOUPE, LFTALP, ALLURE, and OWL-Moon. The science case of LOUPE requires a
location from where the Earth is visible, therefore not the far side of the Moon. The
compatibility with other projects has to be discussed further. Although interferometer
need several telescopes, they would also profit from the logistics lessons provided by. a
single aperture small precursor.
Additional Information
Authors' Contributions
Antoine Labeyrie has conceived and described the lunar hypertelescope. Jean Schneider has
provided science cases.
Competing Interests
The authors declare they have no competing interests.
Funding Statement
Jean Schneider is funded by the Paris Observatory/PSL. Antoine Labeyrie is funded by the
Collège de France
Acknowledgements
18. Jean Schneider is grateful to Roger Angel, Dainis Dravins, Alain Grimaud, Bruno Lacamp and
Jean-Pierre Maillard for discussions.
Data Accessibility
This article has no data.
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