Article
Astronomy & Astrophysics
B. Charnay, G. Tobie, S. Lebonnois, R. D. Lorenz
Summary: By studying Titan's atmosphere, the Dragonfly mission can provide valuable constraints on the interior of Titan.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
M. Rengel, D. Shulyak, P. Hartogh, H. Sagawa, R. Moreno, C. Jarchow, D. Breitschwerdt
Summary: The aim of this study was to measure the vertical distribution of HCN on Titan's stratosphere using ground-based submillimetre observations acquired quasi-simultaneously with the Herschel ones. The results showed consistent HCN abundance profiles and provided valuable information for the improvement of photochemical models. The study received a score of 9 out of 10 for its importance in understanding the vertical distribution of HCN in Titan's stratosphere.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
N. L. Rossignoli, R. P. Di Sisto, M. G. Parisi
Summary: By studying the impact crater counts and erosion processes on Titan, we can estimate its surface age and understand the role of centaur objects in impacts.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
S-Q Wu, X-S Wu, J. Cui, Z-H Yao, Y-T Cao, H-Y Lu, F. He, L. Li, Y. Wei, J-B Cao
Summary: Atmospheric escape on Mars and its relationship with the ionosphere is a critical factor in understanding the loss of habitability. Solar extreme ultraviolet radiation is the main driver of variations in the Martian ionosphere. While the response of ionospheric electrons to this radiation has been well studied, the responses of different ion species are not yet fully understood. This study presents direct observations of periodic variations in photoelectrons and ions, with a common period of approximately 27.2 days and in phase with solar rotation. These variations show significantly different amplitudes, with ion density having a larger amplitude than solar flux and electron density having a smaller amplitude. The species-dependent solar rotation effects provide insights into the upper atmospheric and ionospheric chemistry, highlighting the need to reconsider the composition and variability of any planetary ionosphere driven by solar activity.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
J. Mah, R. Brasser, A. Bouvier, S. J. Mojzsis
Summary: Recent research has found that aside from the traditional view of planet collisions, the accumulation of pebbles can also explain the mass-orbit distribution of terrestrial planets. However, N-body simulations show that pebble accretion played little or no role in the formation of planetary systems in the inner Solar system.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Wolfgang Brandner, Per Calissendorff, Neige Frankel, Faustine Cantalloube
Summary: In this study, we search for additional companions in the GJ 367 exoplanet system and aim to better constrain its age and evolutionary status. By analyzing high-contrast direct imaging observations and comparing them with theoretical models and isochrones, we find conflicting age indicators, suggesting a young age of ≤ 60 Myr based on GAIA EDR3 parallax and photometric measurements, but an age of 1-8 Gyr considering Galactic dynamical evolution. We also find no evidence for warm dust in the GJ 367 system and provide significantly improved detection limits compared to previous studies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Nikolay K. Nikolov, David K. Sing, Jessica J. Spake, Barry Smalley, Jayesh M. Goyal, Thomas Mikal-Evans, Hannah R. Wakeford, Zafar Rustamkulov, Drake Deming, Jonathan J. Fortney, Aarynn Carter, Neale P. Gibson, Nathan J. Mayne
Summary: We present new analysis of infrared transmission spectroscopy of the cloud-free hot-Saturn WASP-96b performed with the Hubble and Spitzer Space Telescopes (HST and Spitzer). The WASP-96b spectrum exhibits the absorption feature from water in excellent agreement with synthetic spectra computed assuming a cloud-free atmosphere. The HST-Spitzer spectrum is coupled with Very Large Telescope (VLT) optical transmission spectroscopy which reveals the full pressure-broadened profile of the sodium absorption feature and enables the derivation of absolute abundances.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Man Ho Chan, Chak Man Lee
Summary: In the past few decades, various modified gravity theories have been proposed to simulate the effect of dark matter. These theories introduce additional apparent force terms in the dynamical equations to replace the role of dark matter. The analytical formula derived in this paper represents the contribution of the precession angle of planets in the Solar system due to general modified gravity theories, where the apparent force terms can be expressed as a power law or exponential function of radius r. Three popular modified gravity theories, modified Newtonian dynamics (MOND), emergent gravity (EG), and modified gravity, were tested. The parameters involved in two popular interpolating functions used in MOND were constrained based on Solar system data.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
H. Gu, X. -S. Wu, J. Cui
Summary: This study aims to evaluate the variations of C and N escape rates on the dayside of Mars during the X8.2 solar flare on 10 September 2017. The results show that the C escape rate reached its minimum about 1 hour after the flare, with an 8% decrease compared to the pre-flare level, while the N escape rate increased by 20% during the same period, followed by a recovery to the pre-flare level.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
S. Hoyer, A. Bonfanti, A. Leleu, L. Acuna, L. M. Serrano, M. Deleuil, A. Bekkelien, C. Broeg, H-G Floren, D. Queloz, T. G. Wilson, S. G. Sousa, M. J. Hooton, V Adibekyan, Y. Alibert, R. Alonso, G. Anglada, J. Asquier, T. Barczy, D. Barrado, S. C. C. Barros, W. Baumjohann, M. Beck, T. Beck, W. Benz, N. Billot, F. Biondi, X. Bonfils, A. Brandeker, J. Cabrera, S. Charnoz, A. Collier Cameron, Sz Csizmadia, M. B. Davies, L. Delrez, O. D. S. Demangeon, B-O Demory, D. Ehrenreich, A. Erikson, A. Fortier, L. Fossati, M. Fridlund, D. Gandolfi, M. Gillon, M. Guedel, N. Hara, K. Heng, K. G. Isaak, J. M. Jenkins, L. L. Kiss, J. Laskar, D. W. Latham, A. Lecavelier des Etangs, M. Lendl, C. Lovis, A. Luntzer, D. Magrin, P. F. L. Maxted, V Nascimbeni, G. Olofsson, R. Ottensamer, I Pagano, E. Palle, C. M. Persson, G. Peter, D. Piazza, G. Piotto, D. Pollacco, R. Ragazzoni, N. Rando, H. Rauer, I Ribas, G. R. Ricker, S. Salmon, N. C. Santos, G. Scandariato, S. Seager, D. Segransan, A. E. Simon, A. M. S. Smith, M. Steller, Gy M. Szabo, N. Thomas, J. D. Twicken, S. Udry, V. Van Grootel, R. K. Vanderspek, N. A. Walton, K. Westerdorff, J. N. Winn
Summary: The HD 108236 system, originally detected with four small planets based on TESS data, was later found to host five small transiting planets with the addition of a fifth planet detected by CHEOPS. By using data from CHEOPS and TESS, the planetary system was characterized, resulting in improved values for the host star parameters and the confirmation of transit timing variations for two of the planets. Further monitoring of the transits, particularly for certain planets, is necessary to confirm observed variations and make HD 108236 a key system for studying formation and evolution processes.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Benno A. Neuenschwander, Ravit Helled
Summary: This paper presents empirical structure models of Uranus and Neptune and predicts their rotation periods and wind depths by using higher order gravitational coefficients. The study finds that faster rotation and deep winds favor centrally concentrated density distributions. Accurate measurements of the gravity field and moment of inertia can constrain their internal structures and wind depths.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Q. Xu, X. Xu, T. L. Zhang, Z. J. Rong, M. Wang, J. Wang, Y. Ye, Z. Zhou, Q. Chang, J. Xu, X. Wang, L. Luo
Summary: The Venusian plasma environment is divided into two regions by the IMB, with its location affected by solar activity and solar wind. The distance of the Venusian IMB on the dayside increases with solar activity but decreases with increasing solar wind dynamic pressure and interplanetary magnetic field cone angle. The behaviors of the IMB are similar to those of the ionopause, indicating a correlation between the distance of the IMB and the scale of the ionosphere.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Nanna Bach-Moller, Uffe G. Jorgensen
Summary: This study reveals a power-law correlation between multiplicity and orbital eccentricities in planetary systems, with the eccentricities of the Solar system fitting the general trend. The outlier in this correlation is consistently the one-planet systems, which may be due to unseen additional exoplanets. Based on this assumption and the power-law correlation, the probability of a system having eight planets or more is estimated to be around 1%, in line with recent predictions.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
H. P. Osborn, D. J. Armstrong, V Adibekyan, K. A. Collins, E. Delgado-Mena, S. B. Howell, C. Hellier, G. W. King, J. Lillo-Box, L. D. Nielsen, J. F. Otegi, N. C. Santos, C. Ziegler, D. R. Anderson, C. Briceno, C. Burke, D. Bayliss, D. Barrado, E. M. Bryant, D. J. A. Brown, S. C. C. Barros, F. Bouchy, D. A. Caldwell, D. M. Conti, R. F. Diaz, D. Dragomir, M. Deleuil, O. D. S. Demangeon, C. Dorn, T. Daylan, P. Figueira, R. Helled, S. Hoyer, J. M. Jenkins, E. L. N. Jensen, D. W. Latham, N. Law, D. R. Louie, A. W. Mann, A. Osborn, D. L. Pollacco, D. R. Rodriguez, B. Rackham, G. Ricker, N. J. Scott, S. G. Sousa, S. Seager, K. G. Stassun, J. C. Smith, P. Strom, S. Udry, J. Villasenor, R. Vanderspek, R. West, P. J. Wheatley, J. N. Winn
Summary: The study reports the discovery of the mini-Neptune exoplanet HD110113 b orbiting a solar-analogue star, with a significantly lower density than expected, indicating a volatile atmosphere. Additionally, the presence of another non-transiting planet HD 110113 c with a higher mass was confirmed.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Yutian Cao, Dandan Niu, Wenjun Liang, Jun Cui, Xiaoshu Wu, Xin Wan, Jiahao Zhong, Lei Li, Zhaojin Rong, Yong Wei
Summary: Thermal electron depression and energetic electron depletion are observed in the nightside Martian ionosphere. While energetic electron depletion has been extensively studied, there is limited research on thermal electron depression and the correlation between the two is unknown. Through Mars Express total electron content (TEC) measurements, a large number of TEC depression features are identified, with large amplitude depression being more frequently observed near strong magnetic fields and small amplitude depression uniformly distributed across the Martian surface.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Michael E. Brown, Konstantin Batygin
Summary: Recent estimates suggest that Planet Nine may be closer and brighter than originally assumed, potentially indicating previous observations. However, no candidates were found in the search through the public archive. By simulating a population of Planet Nine orbits, the study concludes that the survey ruled out 56% of the predicted phase space, providing insights for future analyses.
ASTRONOMICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Matthew Belyakov, Pedro H. Bernardinelli, Michael E. Brown
Summary: Studies suggest the possible existence of a ninth planet beyond Neptune in the outer solar system. By creating a synthetic catalog and examining sky survey results, the parameter space for this planet can be further constrained and provide direction for targeted searches. A study finds that the Dark Energy Survey has a high success rate in recovering planets, ruling out an additional 5% of the parameter space.
ASTRONOMICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Anna M. Simpson, Michael E. Brown, Madeline J. Schemel, Bryan J. Butler
Summary: This study used ALMA measurements to search for high-albedo objects among the mid-sized Jupiter Trojan asteroids, and found several small Trojans with high albedos. The number of these high-albedo objects is consistent with expectations of recent large-scale impacts.
ASTRONOMICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Ian Wong, Michael E. Brown
Summary: Collisional families provide insight into asteroid populations. New observations of the Ennomos family reveal its properties and compositions, including bluer colors and distinct regolith chemistry. Comparisons with the Eurybates family suggest differences in surface spectra and support recent dynamical instability models.
ASTRONOMICAL JOURNAL
(2023)
Article
Multidisciplinary Sciences
Ahmed Mahjoub, Kathrin Altwegg, Michael J. Poston, Martin Rubin, Robert Hodyss, Mathieu Choukroun, Bethany L. Ehlmann, Nora Hanni, Michael E. Brown, Jordana Blacksberg, John M. Eiler, Kevin P. Hand
Summary: The ROSINA instrument aboard the Rosetta mission has advanced our understanding of cometary material composition. By analyzing data from a dust event in September 2016, the study reveals the detection of large organo-sulfur species and an increase in the abundance of sulfurous species in the comet's coma. Laboratory simulations further suggest that these materials may have formed from the irradiation of mixed ices containing H2S. This study emphasizes the significance of sulfur chemistry in cometary and precometary materials, and proposes the possibility of characterizing organosulfur materials in other comets and small icy bodies using the James Webb Space Telescope.
Article
Astronomy & Astrophysics
Katherine de Kleer, Zachariah Milby, Carl Schmidt, Maria Camarca, Michael E. Brown
Summary: The tenuous atmospheres of the Galilean satellites are studied through their auroral emissions, with most focus on UV wavelengths. This study presents the first detections of optical aurorae on Ganymede and Callisto, as well as new optical auroral lines on Europa. Measurements of various emission lines provide robust constraints on atmospheric composition. The study finds predominantly O-2 atmospheres on Europa and Ganymede, with weak evidence of H2O on Europa and only an upper limit for H2O on Ganymede. The electron properties at Callisto's orbit are poorly constrained. Overall, a score of 9 is given.
PLANETARY SCIENCE JOURNAL
(2023)
Review
Astronomy & Astrophysics
Keith S. Noll, Michael E. Brown, Marc W. Buie, William M. Grundy, Harold F. Levison, Simone Marchi, Catherine B. Olkin, S. Alan Stern, Harold A. Weaver
Summary: This chapter reviews the current state of knowledge of Trojan asteroid satellites and discusses their scientific utility and potential observations.
SPACE SCIENCE REVIEWS
(2023)
Article
Geochemistry & Geophysics
Imke de Pater, Emmanuel Lellouch, Darrell F. F. Strobel, Katherine de Kleer, Thierry Fouchet, Michael H. H. Wong, Bryan J. J. Holler, John Stansberry, Patrick M. M. Fry, Michael E. E. Brown, Dominique Bockelee-Morvan, Samantha K. K. Trumbo, L. N. Fletcher, Matthew M. M. Hedman, Edward M. M. Molter, Mark Showalter, Matthew S. S. Tiscareno, Stephanie Cazaux, Ricardo Hueso, Statia Luszcz-Cook, Henrik Melin, Chris Moeckel, Alessandro Mura, Glenn Orton, Lorenz Roth, Joachim Saur, Federico Tosi
Summary: We observed thermal emissions from several volcanoes on Io using the James Webb Space Telescope (JWST) during the satellite's eclipse. The brightest volcano, Kanehekili Fluctus, had a temperature of around 1,200 K and originated from an area of about 0.25 km². Loki Patera, another volcano, also showed high temperatures confined to an area of about 0.06 km². We also detected SO emissions above Kanehekili Fluctus for the first time, suggesting that these emissions are produced by SO molecules ejected from the vent.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2023)
Article
Multidisciplinary Sciences
Samantha K. K. Trumbo, Michael E. E. Brown, Dominique Bockelee-Morvan, Imke de Pater, Thierry Fouchet, Michael H. H. Wong, Stephanie Cazaux, Leigh N. Fletcher, Katherine de Kleer, Emmanuel Lellouch, Alessandro Mura, Olivier Poch, Eric Quirico, Pablo Rodriguez-Ovalle, Mark R. R. Showalter, Matthew S. S. Tiscareno, Federico Tosi
Summary: Ganymede, the only satellite with an intrinsic magnetic field, experiences interactions with the Jovian magnetosphere, resulting in the accumulation of charged particles in its polar regions. Observations with JWST have revealed the presence of hydrogen peroxide, a product of radiolysis, at high latitudes, indicating the modification of polar caps by precipitation of Jovian charged particles along partially open field lines within Ganymede's magnetosphere. This discovery, along with the contrasting distribution of hydrogen peroxide on Europa, has important implications for understanding water-ice radiolysis in the solar system.
Article
Astronomy & Astrophysics
Michael E. E. Brown, Wesley C. C. Fraser
Summary: JWST observations reveal the presence of CO2 and CO on the surfaces of objects in the Kuiper Belt, with higher coverages than water ice, suggesting a volatile differentiation process. The unusual spectral behavior of CO2 around the 4.26 & mu;m & nu; (1) band can be explained by a surface covered in a few micron thick layer of & SIM;1-2 & mu;m CO2 particles. CO, which is unstable at Kuiper Belt temperatures, is suggested to be created via irradiation of CO2 and trapped in CO2 grains, indicating a trapping mechanism different from hydrate clathrates or amorphous ice.
PLANETARY SCIENCE JOURNAL
(2023)
Article
Astronomy & Astrophysics
Michael E. Brown, Bryan J. Butler
Summary: Using the Atacama Large Millimeter/submillimeter Array, we accurately measured the absolute astrometric positions of the dwarf planet Orcus and its satellite Vanth, and detected their astrometric wobble. We also estimated the upper limit of the astrometric wobble caused by the satellite Dysnomia on the dwarf planet Eris. The mass ratio of Vanth-Orcus was found to be the highest among any known planet or dwarf planet, indicating that Vanth may have originated from a giant collision in the system and that the system has likely evolved to a double synchronous state. We only obtained an upper limit for the barycenter motion of Eris, suggesting a 1 sigma upper limit to the Dysnomia-Eris mass ratio, which is close to the transition region between impact-generated satellites and those formed from reaccreted disk material.
PLANETARY SCIENCE JOURNAL
(2023)
Article
Astronomy & Astrophysics
Samantha K. Trumbo, Tracy M. Becker, Michael E. Brown, William T. P. Denman, Philippa Molyneux, Amanda Hendrix, Kurt D. Retherford, Lorenz Roth, Juan Alday
Summary: Recent observations using the Hubble Space Telescope have identified absorption features on Europa's surface, believed to be caused by sodium chloride. Further analysis with ultraviolet spectra revealed additional absorption features, providing important insights into Europa's subsurface composition.
PLANETARY SCIENCE JOURNAL
(2022)
Article
Astronomy & Astrophysics
Samantha K. K. Trumbo, M. Ryleigh Davis, Benjamin Cassese, Michael E. E. Brown
Summary: The article presents global, spatially resolved ultraviolet-visible spectra of Io, revealing the chemistry behind its volcanic hues. Through mapping and spectral analysis, the study identifies spectral features associated with SO2 frost and other sulfur species, and explores possible compositions in the context of Io surface processes.
PLANETARY SCIENCE JOURNAL
(2022)
Article
Astronomy & Astrophysics
William T. P. Denman, Samantha K. Trumbo, Michael E. Brown
Summary: By irradiating sodium chloride, scientists have found that the absorption feature of F-centers on Europa is consistent with laboratory measurements, confirming the presence of this salt on Europa.
PLANETARY SCIENCE JOURNAL
(2022)
Article
Astronomy & Astrophysics
Michael E. E. Brown, William T. P. Denman, Samantha K. K. Trumbo
Summary: Recent observations from the Hubble Space Telescope show a mid-UV absorption feature localized to leading-hemisphere chaos regions on Europa. Laboratory experiments demonstrate that irradiated NaCl at Europa's surface temperatures develops an absorption at around 220 nm, consistent with the new detection in Europa's mid-UV spectrum. This supports the identification of NaCl in Europa's subsurface ocean.
PLANETARY SCIENCE JOURNAL
(2022)