Article
Astronomy & Astrophysics
Nicholas A. Lombardo, Juan M. Lora
Summary: Titan's atmosphere shows variations in composition as it goes through different seasons. Winter stratosphere above 100 km has been found to have higher amounts of short-lived molecules. Seasonal changes in stratospheric dynamics on Titan also lead to a transient detached haze layer above 400 km. These seasonal variations affect the radiative heating rates in both shortwave and longwave regions. Based on simulations using the Titan Atmospheric Model (TAM), this study examines the impact of a new dataset derived from Cassini observations on aerosol opacity and trace gas abundance. The results show that including seasonally varying radiative species (SVRS) decreases the temperature of polar stratopause in autumn and winter by up to 10 K, and increases the seasonality in zonal winds.
Article
Astronomy & Astrophysics
Erich Karkoschka
Summary: An analysis of three new image cubes of Titan by the Space Telescope Imaging Spectrograph reveals that Titan's seasonal variation is close to harmonic and not influenced by variations due to Saturn's orbital eccentricity. The reversal consists of two components, with small temporary deviations observed. These new observations provide an improved seasonal model that will help in future global circulation models of Titan.
Article
Astronomy & Astrophysics
Tetsuya Tokano
Summary: The paleoclimate of Titan, Saturn's moon, in the presence of hypothetical hydrocarbon oceans 1 Gyr ago was simulated using a global climate model with a slab ocean model. The study found that the composition of the ocean and the presence of continents have significant impacts on the climate. Methane-rich oceans result in a moist and calm climate, while ethane-rich oceans are drier and windier.
Article
Astronomy & Astrophysics
Michael J. Person, Amanda S. Bosh, Carlos A. Zuluaga, Amanda A. Sickafoose, Stephen E. Levine, Jay M. Pasachoff, Bryce A. Babcock, Edward W. Dunham, Ian S. McLean, Jurgen Wolf, Fumio Abe, E. E. Becklin, Thomas A. Bida, Len P. Bright, Tim Brothers, Grant Christie, Rebecca F. Durst, Alan C. Gilmore, Ryan T. Hamilton, Hugh C. Harris, Chris Johnson, Pamela M. Kilmartin, Molly Kosiarek, Karina Leppik, Sarah E. Logsdon, Robert Lucas, Shevill Mathers, C. J. K. Morley, Peter Nelson, Haydn Ngan, Enrico Pfuller, Tim Natusch, Stephanie Sallum, Maureen L. Savage, Christina H. Seeger, Ho Chit Siu, Chris Stockdale, Daisuke Suzuki, Thanawuth Thanathibodee, Trudy Tilleman, Paul J. Tristram, William D. Vacca, Jeffrey Van Cleve, Carolle Varughese, Luke W. Weisenbach, Elizabeth Widen, Manuel Wiedemann
Summary: On 29 June 2015, the occultation by Pluto of a bright star was observed from multiple ground-based stations and the Stratospheric Observatory for Infrared Astronomy (SOFIA). Analysis of the data shows that there has been no significant expansion or contraction of Pluto's middle atmosphere, and a haze component is required to reproduce the observed light curves, affecting the understanding of the atmosphere's photochemistry.
Article
Astronomy & Astrophysics
M. Dobrijevic, J. C. Loison, V Hue, T. Cavalie
Summary: Observational data of Titan's atmosphere composition, gathered by missions like Cassini, provide insights into the dynamics of various chemical species' altitude profiles. Developing a 2D photochemical model for Titan that considers complex chemical schemes and latitudinal variations has shown to significantly impact the accuracy of density profiles for neutrals and ions. Therefore, the use of radiative transfer models in a 2D geometry is recommended for interpreting observational data about Titan's atmosphere.
Article
Astronomy & Astrophysics
Dhvani Doshi, Nicolas B. Cowan, Yi Huang
Summary: The James Webb Space Telescope (JWST) will provide an opportunity to investigate the atmospheres of potentially habitable planets. This study explores the impact of aerosols and clouds on JWST's ability to observe deeper layers of exoplanetary atmospheres. The research finds that JWST would not be able to detect Earth-like stratospheric clouds in the TRAPPIST-1 system, but it would be able to detect them in the habitable zone of a white dwarf after only four transits.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Chemistry, Physical
Alina Begley, Nicholas S. Shuman, Bryan A. Long, Robin Kampf, Luzia Gyr, Albert A. Viggiano, Renato Zenobi
Summary: This paper investigates the direct formation of N-heterocycles from aromatic hydrocarbons in low temperature nitrogen-based plasmas, and focuses on the mechanism behind this nitrogen fixation reaction. Using a DBDI source, toluene was studied as a model compound, revealing the formation of a nitrogen-replacement product and a nitrogen-addition product under high plasma voltage.
JOURNAL OF PHYSICAL CHEMISTRY A
(2022)
Article
Astronomy & Astrophysics
A. Maattanen, F. Lefevre, L. Verdier, F. Montmessin, C. Listowski, S. Guilbon, A. Fedorova, O. Korablev
Summary: The SPICAM/MEX UV spectrometer used occultation method to probe the Martian atmosphere and obtained good spatial and seasonal coverages. The study analyzed the observations of Martian ozone and compared them with a global climate model, showing overall agreement with quantitative differences in certain regions. This research provides important data for studying Martian ozone.
Article
Astronomy & Astrophysics
M. Luginin, A. Fedorova, D. Belyaev, F. Montmessin, O. Korablev, J. -l. Bertaux
Summary: Spectroscopic solar occultation measurements by the SPICAV/SOIR instrument onboard the Venus Express orbiter provided new data on the upper haze aerosol properties, its distribution, and variations. A joint analysis of data from two spectrometers revealed a bimodal distribution in about 50% of observations previously believed to be unimodal, and characterized the size distribution 10 km higher in the atmosphere compared to previous analysis.
Article
Astronomy & Astrophysics
Atila Poro, Farzaneh Ahangarani Farahani, Majid Bahraminasr, Maryam Hadizadeh, Fatemeh Najafi Kodini, Maryam Rezaee, Mahsa Seifi Gargari
Summary: The study observed Pluto's stellar occultation in Iran in June 2020 and investigated its atmospheric parameters, finding a continuation of the pressure increase trend since 1988. The results indicate that the N2 sublimation process from Sputnik Planitia is ongoing.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
A. Bourgoin, M. Zannoni, L. Gomez Casajus, P. Tortora, P. Teyssandier
Summary: This study introduces a covariant method to describe time and frequency transfers during atmospheric occultation experiments by utilizing the optical metric and time transfer function formalism. The authors provide comprehensive analytical expressions for the time transfer function, focusing on the stationary optical metric describing occultations by a rotating and spherically symmetric atmosphere, and validate the accuracy of the analytical expressions by comparing them to numerical integration results.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Darrell F. Strobel
Summary: The paper aims to investigate whether the H-2 density measurements reported by Cassini were overestimated by a factor of 2.2, and the potential impact of this overestimation on the atmospheres of Titan and Saturn.
Article
Optics
Brendan L. Steffens, Keeyoon Sung, Michael J. Malaska, Rosaly M. C. Lopes, Geoffrey C. Toon, Conor A. Nixon
Summary: We measured cross-sections for trans-2-butene in the mid-infrared range to support remote sensing of Titan's atmosphere. The results provide laboratory input for future observations and data analysis. The study achieved a high-resolution characterization and compiled the data in a readily integrable database format.
JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER
(2023)
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
Joachim W. Stock, Daniel Kitzmann, A. Beate C. Patzer
Summary: The updated version of the thermochemical equilibrium code FASTCHEM, called FASTCHEM 2, is introduced. It offers the capability to compute complex neutral and ionized chemical equilibrium compositions for various scenarios, including atmospheres dominated by species other than hydrogen. The program has been extensively tested and validated, showing improved computational performance and applicability compared to the previous version.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
M. Ciarniello, G. Filacchione, E. D'Aversa, F. Capaccioni, P. D. Nicholson, J. N. Cuzzi, R. N. Clark, M. M. Hedman, C. M. Dalle Ore, P. Cerroni, C. Plainaki, L. J. Spilker
Article
Multidisciplinary Sciences
Matthew S. Tiscareno, Philip D. Nicholson, Jeffrey N. Cuzzi, Linda J. Spilker, Carl D. Murray, Matthew M. Hedman, Joshua E. Colwell, Joseph A. Burns, Shawn M. Brooks, Roger N. Clark, Nicholas J. Cooper, Estelle Deau, Cecile Ferrari, Gianrico Filacchione, Richard G. Jerousek, Stephane Le Mouelic, Ryuji Morishima, Stu Pilorz, Sebastien Rodriguez, Mark R. Showalter, Sarah V. Badman, Emily J. Baker, Bonnie J. Buratti, Kevin H. Baines, Christophe Sotin
Article
Astronomy & Astrophysics
R. O. Chancia, M. M. Hedman, S. W. H. Cowley, G. Provan, S-Y Ye
Article
Astronomy & Astrophysics
Lynnae C. Quick, Aki Roberge, Amy Barr Mlinar, Matthew M. Hedman
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC
(2020)
Article
Geochemistry & Geophysics
H. Sharma, M. M. Hedman, D. H. Wooden, A. Colaprete, A. M. Cook
Summary: Studying lunar dust is crucial for exploring the Moon and other airless planetary bodies. By using a spectrometer on board the Lunar Atmosphere and Dust Environment Explorer spacecraft, constraints can be placed on the number density of dust particles near the lunar surface, aiding in further research.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2021)
Article
Astronomy & Astrophysics
C. Paranicas, E. Roussos, K. Dialynas, P. Kollmann, N. Krupp, M. Hedman, R. C. Allen, G. Hospodarsky
Summary: Cassini data confirm the presence of a global electric field in Saturn's magnetosphere that influences charged particle drift paths near the outer edge of the A ring. The measurements of ultrarelativistic electrons provide no information about the electric field. This result strengthens the case for using the presence of the electric field to explain acceleration signatures in the data.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Joseph A. A'Hearn, Matthew M. Hedman, Christopher R. Mankovich, Hima Aramona, Mark S. Marley
Summary: In this study, we assess the potential of using ring seismology to investigate the interiors of Uranus and Neptune. By calculating normal-mode spectra for different interior models of these planets, we determine the regions in their ring systems where the effects of interior oscillations can be detected. We find that certain resonances occur within the rings of Uranus, while others are present in the tenuous ring region of Neptune. Additionally, g-mode resonances may be found in the outer rings of these planets.
PLANETARY SCIENCE JOURNAL
(2022)
Article
Astronomy & Astrophysics
M. M. Hedman, P. D. Nicholson, M. El Moutamid, S. Smotherman
Summary: The study revealed multiple density wave structures in Saturn's C ring that are driven by time-variable anomalies in the planet's gravitational field. Analysis of these structures provides information about changes in the gravitational anomalies over time, with some structures being transient and others persisting for decades, including one whose rotation rate has steadily increased over the past few decades.
PLANETARY SCIENCE JOURNAL
(2022)
Article
Astronomy & Astrophysics
M. M. Hedman, M. Young
Summary: Saturn's E ring is composed of micron-sized particles ejected from Enceladus due to the moon's geological activity. Various small-scale structures in the E ring's brightness are attributed to recent material launched from Enceladus. The presence of wake structures near Enceladus's orbit could provide valuable insights into the orbital properties and evolution of E-ring particles, particularly those with low eccentricities and semimajor axes just outside of Enceladus's orbit.
PLANETARY SCIENCE JOURNAL
(2021)
Correction
Astronomy & Astrophysics
Matthew Hedman, Bill Bridges
PLANETARY SCIENCE JOURNAL
(2021)
Article
Astronomy & Astrophysics
Matthew Hedman, Rob Chancia
Summary: In addition to a suite of narrow dense rings, Uranus is surrounded by a complex system of dusty rings, with some less than 20 km wide. The extreme narrowness of these rings and their lack of proximity to known satellite resonances are expected to provide new insights into the forces shaping the Uranian ring system.
PLANETARY SCIENCE JOURNAL
(2021)
Article
Astronomy & Astrophysics
Joseph A. A'Hearn, Matthew M. Hedman, Douglas P. Hamilton
Summary: The D68 ringlet in Saturn's rings is hypothesized to be formed by source bodies in a co-orbital configuration, but the existence of a fifth co-orbital object to account for discrepancies in angular separations seems more plausible. Numerical simulations show that the stability of a co-orbital system model for D68 is fragile, suggesting the presence of an external force controlling the material in this ringlet.
PLANETARY SCIENCE JOURNAL
(2021)
Article
Astronomy & Astrophysics
Mathew Hedman, Bill Bridges
PLANETARY SCIENCE JOURNAL
(2020)
Article
Astronomy & Astrophysics
M. M. Hedman, P. Helfenstein, R. O. Chancia, P. Thomas, E. Roussos, C. Paranicas, A. J. Verbiscer
ASTRONOMICAL JOURNAL
(2020)
Article
Astronomy & Astrophysics
Steven M. Kreyche, Jason W. Barnes, Billy L. Quarles, Jack J. Lissauer, John E. Chambers, Matthew M. Hedman
PLANETARY SCIENCE JOURNAL
(2020)
Article
Astronomy & Astrophysics
Maria Angeles Lopez-Cayuela, Maria-Paz Zorzano, Juan Luis Guerrero-Rascado, Carmen Cordoba-Jabonero
Summary: The atmospheric dust cycle on Mars plays a dominant role in the planetary radiative balance, atmospheric photochemistry escape, and redistribution of materials on the surface. A methodology is presented to accurately describe the annual dust redistribution cycle on Mars using orbital global and seasonal measurements of atmospheric dust opacity. The analysis shows that approximately 4 trillion kilograms of dust is transported globally in the atmosphere during a typical Mars year.
Article
Astronomy & Astrophysics
Audrey Vorburger, Shahab Fatemi, Shane R. Carberry Mogan, Andre Galli, Lucas Liuzzo, Andrew R. Poppe, Lorenz Roth, Peter Wurz
Summary: The study presents new model results for the composition of Ganymede's atmosphere, finding that sublimation remains the major source process for H2O, while radiolysis induced by auroral electrons dominates the source fluxes for O2 and H2.
Article
Astronomy & Astrophysics
Qi He, Zhi Cao, Yuqi Qian, Hejiu Hui, Ioannis Baziotis, Long Xiao, Zaicong Wang, Biji Luo, Yiheng Li, Zongjun Ying, Yang Li
Summary: The Chang'e-5 mission collected lunar soil containing magnesian troctolitic granulites, which provide valuable information on the composition of the lunar crust. Through analysis and modeling, it is suggested that these granulites may have originated from the Pythagoras crater and were transported to the landing site.
Article
Astronomy & Astrophysics
Jordan M. Bretzfelder, Kathryn M. Stack, Abigail A. Fraeman, Mackenzie Day, William E. Dietrich, Alexander B. Bryk
Summary: This study investigates the development of bedrock ridges on Mars and their implications for wind history, deposition, and erosion in Gale crater.
Article
Astronomy & Astrophysics
Lot Ram, Diptiranjan Rout, Rahul Rathi, Paul Withers, Sumanta Sarkhel
Summary: This study investigates the impacts of interplanetary coronal mass ejections (ICMEs) on the Martian ionosphere, specifically the behavior of the ionospheric peak density and height during ICME passages. The study used observations from the Radio Occultation Science Experiment (ROSE) aboard the MAVEN spacecraft and selected 8 ICMEs from existing catalogs. The results show that ICMEs lead to an elevation of the ionospheric peak height and a decrease in peak density, and propose that vertical pressure gradient and electron temperature enhancement are plausible causes for ionospheric variability.
Article
Astronomy & Astrophysics
Benoit Jabaud, Riccardo Artoni, Gabriel Tobie, Erwan Le Menn, Patrick Richard
Summary: The Cassini spacecraft discovered active jets of water vapour and ice grains at the South Pole of Enceladus, resulting in the deposit of freshly erupted materials on the moon's icy surface. Similar processes may be happening on Europa as well. Determining the mechanical properties of fresh icy powder-like materials is essential for future landing and sampling missions. The flowability and surface energy of ice powders decrease with increasing temperatures, which may have implications for stable landing and the flow of ice materials on Enceladus and Europa.
Article
Astronomy & Astrophysics
Lydie Bonal, Eric Quirico, Gilles Montagnac, Mutsumi Komatsu, Yoko Kebukawa, Hikaru Yabuta, Kana Amano, Jens Barosch, Laure Bejach, George D. Cody, Emmanuel Dartois, Alexandre Dazzi, Bradley De Gregorio, Ariane Deniset-Besseau, Jean Duprat, Cecile Engrand, Minako Hashiguchi, Kanami Kamide, David Kilcoyne, Zita Martins, Jeremie Mathurin, Smail Mostefaoui, Larry Nittler, Takuji Ohigashi, Taiga Okumura, Laurent Remusat, Scott Sandford, Miho Shigenaka, Rhonda Stroud, Hiroki Suga, Yoshio Takahashi, Yasuo Takeichi, Yusuke Tamenori, Maximilien Verdier-Paoletti, Shohei Yamashita, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Hisayoshi Yurimoto, Shogo Tachibana, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Satoru Nakazawa, Masahiro Nishimura, Tatsuaki Okada, Takanao Saiki, Kanako Sakamoto, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Tomohiro Usui, Sei-ichiro Watanabe, Toru Yada, Kasumi Yogata, Makota Yoshikawa
Summary: This paper focuses on characterizing the thermal history of asteroid Ryugu by studying the structure of polyaromatic carbonaceous matter in the returned samples. The study finds that there is no structural difference in the polyaromatic component between the two sampling sites on Ryugu, indicating that the thermal metamorphism related to radioactive decay was not significant. However, some structural variability is observed within the particle set.
Article
Astronomy & Astrophysics
M. Luginin, A. Fedorova, D. Belyaev, F. Montmessin, O. Korablev, J. -l. Bertaux
Summary: Spectroscopic solar occultation measurements by the SPICAV/SOIR instrument onboard the Venus Express orbiter provided new data on the upper haze aerosol properties, its distribution, and variations. A joint analysis of data from two spectrometers revealed a bimodal distribution in about 50% of observations previously believed to be unimodal, and characterized the size distribution 10 km higher in the atmosphere compared to previous analysis.
Article
Astronomy & Astrophysics
A. Mahieux, S. Viscardy, K. L. Jessup, F. P. Mills, L. Trompet, S. Robert, S. Aoki, A. Piccialli, A. C. Vandaele
Summary: We report on the mean upper limit number densities and volume concentrations of H2CO, O-3, NH3, HCN, N2O, NO2, NO, and HO2 at the Venus terminator above the cloud layer. Attempts to detect these species using a statistical algorithm and the method presented by Trompet et al. (2021) were unsuccessful, and upper limits of detection are provided.
Article
Astronomy & Astrophysics
P. M. Streeter, S. R. Lewis, M. R. Patel, J. A. Holmes, K. Rajendran
Summary: The northern polar vortex on Mars shows a high degree of interannual repeatability in its structure and evolution, except during large dust storms. The seasonal timing of these storms seems to be the key factor determining their impacts on the polar vortex.
Article
Astronomy & Astrophysics
Michael T. Mellon, Hanna G. Sizemore, Jennifer L. Heldmann, Christopher P. McKay, Carol R. Stoker
Summary: The search for life is a major focus of Mars exploration, with temperature and water activity being key factors for habitability. The most recent habitable conditions occurred about 510 kyrs ago and lasted for about 10s of kyrs each occurrence. All latitudes offer potential for life exploration, but middle-latitude sites have access to 100-kyr-old ice that experienced past habitable conditions, while high-latitude sites offer access to ancient ice over 1 Myrs old.
Article
Astronomy & Astrophysics
Anthony Ozerov, Jeffrey C. Smith, Jessie L. Dotson, Randolph S. Longenbaugh, Robert L. Morris
Summary: The Geostationary Lightning Mapper (GLM) instruments, with their large combined field of view, are useful for studying the population of atmospheric phenomena like bolides. However, there are biases when using GLM for non-lightning purposes, which need to be studied and accounted for before precise measurements of bolide flux can be obtained. A Bayesian Poisson regression model was developed to estimate instrumental biases and the latitudinal variation of bolide flux concurrently. The estimated bias corresponds to the known sensitivity of the GLM instruments, and the latitudinal flux variation estimates are consistent with a strong bias towards high-velocity bolides, as compared to existing theoretical models.
Article
Astronomy & Astrophysics
P. Beck, P. Y. Meslin, A. Fau, O. Forni, O. Gasnault, J. Lasue, A. Cousin, S. Schroeder, S. Maurice, W. Rapin, R. C. Wiens, A. M. Ollila, E. Dehouck, N. Mangold, B. Garcia, S. Schwartz, W. Goetz, N. Lanza
Summary: Analysis of data obtained by ChemCam on Mars reveals that the carbon signal is mainly related to ionization of the atmosphere, with variability potentially linked to the physical state of the atmosphere. Up to sol 3355, no carbonate was detected in the ChemCam dataset, suggesting that it is not a major constituent (>50%) in the analyzed targets and that carbon in soils is not enriched beyond the limit of detection. The dominant salts found in Gale are sulfate and chlorides, while the absence of carbonates, seen in Jezero, may be due to differences in protolith.
Article
Astronomy & Astrophysics
Eloy Pena-Asensio, Jaakko Visuri, Josep M. Trigo-Rodriguez, Hector Socas-Navarro, Maria Gritsevich, Markku Siljama, Albert Rimola
Summary: The observation of interstellar objects 1I/'Oumuamua and 2I/Borisov suggests the existence of a larger population of smaller projectiles that impact our planet with unbound orbits. A statistical evaluation of uncertainties in the CNEOS database and study of its hyperbolic fireballs reveals an anisotropic geocentric radiant distribution and low orbital inclinations, challenging the assumption of a randomly incoming interstellar population. These findings suggest that apparent interstellar meteors may, in fact, be the result of accelerated meteoroid impacts caused by close encounters with massive objects within or passing through our solar system.
Article
Astronomy & Astrophysics
Cecilia W. S. Leung, Leslie K. Tamppari, David M. Kass, German Martinez, Erik Fischer, Michael D. Smith
Summary: Using a combination of orbital and surface observations, this study investigates the vertical distribution of water vapor in the lower atmospheres of Mars. The findings suggest that the assumption of uniformly mixed water vapor in the boundary layer is not always consistent with observational constraints. The results provide important insights into the seasonal transport of water and the role of regolith-atmospheric exchange.