Article
Astronomy & Astrophysics
K. Dapre, J. C. E. Irving
Summary: This study investigates the effects of ice shell and ocean thickness, as well as core structure and composition, on the waveforms recorded by a single seismometer for three 1D models of Enceladus. The results suggest that core-transmitted and -reflected phases can be observed even at low epicentral distances, providing constraints on ocean depth and core structure.
Article
Astronomy & Astrophysics
Nicholas Z. Rui, Jim Fuller
Summary: Strong magnetic fields in stellar cores can suppress dipole modes observed in red giants. The interaction between g-mode spectrum and Alfven waves produces discontinuous features in fluid displacements. Magnetogravity modes become evanescent in regions with strong magnetic fields, while ingoing gravity waves are refracted into outgoing slow magnetic waves. These findings suggest the possible escape of a small fraction of wave power as pure Alfven waves or magnetogravity waves confined to a narrow equatorial band.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
S. K. Lander, P. Haensel, B. Haskell, J. L. Zdunik, M. Fortin
Summary: The study explores the thermal and magnetic field structure of a late-stage proto-neutron star, establishing a simplified equation of state for hot neutron stars and solving the stellar equilibrium equations numerically. The ellipticity increases with temperature for a fixed magnetic field strength, and the Keplerian velocity is considerably lower for hotter stars. Magnetic fields stronger than around 10^14 G have qualitatively similar equilibrium states in both hot and cold neutron stars, with the poloidal field component dominating over the toroidal one.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Vishnu Varma, Bernhard Mueller
Summary: In the first 3D MHD simulation of convective oxygen and neon shell burning in a non-rotating star, magnetic fields in supernova progenitors were studied. The magnetic field approaches saturation levels in the oxygen shell, but does not reach kinetic equipartition.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Shyeh Tjing Loi
Summary: The complex interplay of rotation and magnetism in evolved stars requires proper modeling of both factors to draw robust conclusions about the existence of a core magnetic field in any given object.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Clara Dehman, Daniele Vigano, Stefano Ascenzi, Jose A. Pons, Nanda Rea
Summary: We perform 3D fully coupled magneto-thermal simulations of neutron stars with complex initial magnetic field topology. The surface dipolar component does not increase over time, contradicting the observed properties of young pulsars and magnetars.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Yu-Qing Lou, Jing-Ze Ma
Summary: Gravitational dynamic collapses of supermassive stars can result in the formation of black holes in various mass ranges. The presence of magnetic fields affects the stability of these collapses, with higher magnetic energy increasing the upper mass limit for instability. Magnetized stars also show a shifted evolutionary track and the potential for powerful electromagnetic wave bursts.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Physics, Fluids & Plasmas
L. Simons, A. Long
Summary: The study modeled the rotational dynamics of spherical, conducting dust grains in collisionless plasmas due to asymmetric momentum and current collection in the presence of a uniform magnetic field. It found the dependence of torque, equilibrium rotation rate, and equilibration timescale on the strength of the magnetic field and the surface potential, as well as explained observed rotations of isolated dust grains in low temperature discharges.
PHYSICS OF PLASMAS
(2021)
Article
Biochemistry & Molecular Biology
Danuta Kruk, Elzbieta Masiewicz, Sylwia Lotarska, Roksana Markiewicz, Stefan Jurga
Summary: H-1 spin-lattice relaxation experiments were conducted on a series of ionic liquids containing different alkyl chain lengths of bis(trifluoromethanesulfonyl)imide anion and cations. The results provided insights into the rotational and translational dynamics of the cations in comparison to molecular liquids, indicating a temperature-dependent ratio between the correlation times of these motions.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2022)
Article
Astronomy & Astrophysics
C. G. A. Smith
Summary: A three-dimensional linear model was developed to explain Saturn's planetary period oscillations, focusing on the interaction of Rossby waves and current systems. The model successfully describes observed current systems when opposite hemispheres have distinct PPO periods. However, the model falls short in explaining why the PPO current systems become 'locked' together with a specific phase relationship.
Article
Astronomy & Astrophysics
Deborah Bardet, Aymeric Spiga, Sandrine Guerlet, Simon Cabanes, Ehouarn Millour, Alexandre Boissinot
Summary: The study extended the DYNAMICO-Saturn global climate model (GCM) to the upper stratosphere to investigate the equatorial oscillation phenomenon similar to the Earth's Quasi-Biennial Oscillation (QBO) and the seasonal eastward jets correlated with Saturn's rings. The impact of rings' shadowing on Saturn's stratospheric dynamics was also analyzed, showing a weakened QBO-like oscillation due to increased drag caused by changes associated with rings' shadowing.
Article
Astronomy & Astrophysics
James S. D. Blake, L. N. Fletcher, G. S. Orton, A. Antunano, M. T. Roman, Y. Kasaba, T. Fujiyoshi, H. Melin, D. Bardet, J. A. Sinclair, M. Es-Sayeh
Summary: Ground-based mid-infrared images of Saturn over a multi-decade period reveal seasonal and non-seasonal variability in thermal emission. 8-m class observatories can resolve thermal contrasts on various scales and confirm the consistency of Saturn's thermal structure from year to year. However, inter-annual variations are observed in the equatorial banding, suggesting the influence of tropospheric meteorology.
Article
Engineering, Electrical & Electronic
C. Iacovita, M. Vomir, B. Donnio, J. L. Gallani, M. V. Rastei
Summary: We report a method for measuring variations of magnetic field gradients generated by macroscopic coils. The method utilizes a micromechanical cantilever oscillator covered with a magnetic material to detect changes in the magnetic force field at distances greater than the coil's diameter. The detection sensitivity, estimated to be around 10-13 T/ nm2, is achieved by modulating the magnetic field at low frequencies and utilizing the nanoscale oscillation of the cantilever. This approach has potential applications in magnetic resonance imaging, stray magnetic field detection, power monitoring, 3D magnetic field mapping, and miniature orientation devices.
SENSORS AND ACTUATORS A-PHYSICAL
(2022)
Article
Astronomy & Astrophysics
Ronald M. Caplan, Cooper Downs, Jon A. Linker, Zoran Mikic
Summary: This study investigates the potential field solutions for the global coronal magnetic field on June 13, 2012, and explores how different choices in boundary conditions, resolution, and input maps may influence the solution properties. The results show that coronal morphology and magnetic flux are most strongly influenced by the outer boundary condition, while large-scale morphologies and open magnetic flux are insensitive to model resolution.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Fabio Ferrari, Paolo Tanga
Summary: Multiple sources of evidence suggest that small asteroids ranging from hundreds meters to few kilometers in size are made up of loosely consolidated rubble piles. Recent observations and simulations indicate that a rigid core within the rubble-pile structure can explain the top shape and surface features observed on certain asteroids, without the need for cohesion between building blocks. The presence of a rigid core is consistent with the accretion history and internal mass distribution of these objects.
Article
Geosciences, Multidisciplinary
Rakesh Kumar Yadav, Hao Cao, Jeremy Bloxham
Summary: Saturn's magnetic field is highly axisymmetric, with a very small tilt angle of the magnetic dipole component. Numerical simulations suggest that small dipole tilt values can be realized by introducing spatial heat-flux variation and stably stratified layers on top of an active dynamo layer. This study presents a simplified model that achieves extremely small dipole tilt values without these ad hoc ingredients.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geochemistry & Geophysics
Jeremy Bloxham, Kimberly M. Moore, Laura Kulowski, Hao Cao, Rakesh K. Yadav, David J. Stevenson, John E. P. Connerney, Scott J. Bolton
Summary: A key objective of the Juno mission is to determine the secular variation of Jupiter's internal magnetic field. This study finds that the residuals to a static model of the magnetic field are consistent with the effects of secular variation arising from zonal drift. The researchers present a technique for simultaneously inverting for the main magnetic field and the secular variation due to zonal drift, and find good agreement with previous studies. It suggests that the drift rate of Jupiter's magnetic field is steady over time periods of several decades.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2022)
Article
Physics, Multidisciplinary
Michael Gedalin, Ephim Golbraikh, Christopher T. Russell, Andrew P. Dimmock
Summary: The Mach number is a crucial parameter for collisionless shocks, and understanding shock physics requires knowledge of the spatial scales within the shock transition layer. Standard methods for determining the Mach number and spatial scales typically require measuring the magnetic field as well as particle density, velocity, and temperature. However, particle measurements are often unavailable or not properly adjusted to the plasma conditions. This study demonstrates that theoretical arguments can be used to overcome these observational limitations and determine the Mach number and spatial scales of low-Mach number shocks using only magnetic field data.
FRONTIERS IN PHYSICS
(2022)
Article
Geosciences, Multidisciplinary
Zhekai Luo, Lun Xie, Suiyan Fu, Zuyin Pu, Ying Xiong, Xuzhi Zhou, Qiugang Zong, Li Li, C. T. Russell, R. E. Ergun, J. L. Burch, J. B. Blake, R. B. Torbert, P. -A. Lindqvist
Summary: This paper analyzes the features of drift resonance in microinjection phenomena and proposes a new theory that includes bouncing electrons. The observed phase differences in microinjection events are consistent with the predicted phase differences based on the new theory, suggesting that drift resonance may act as the forming mechanism for microinjections.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
Yuri Y. Y. Shprits, Ingo Michaelis, Dedong Wang, Hayley Allison, Ruggero Vasile, Andrei Runov, Alexander Drozdov, Christopher T. Russell, Vladimir Kalegaev, Artem Smirnov
Summary: This study used measurements from the ELFIN-L suit of instruments on the Lomonosov spacecraft to distinguish between stably trapped and drift loss cone electrons. The results show that the loss at MeV energies mainly occurs on the dawn-side, consistent with loss induced by chorus waves.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Physics, Fluids & Plasmas
Michael Gedalin, Andrew P. Dimmock, Christopher T. Russell, Nikolai V. Pogorelov, Vadim Roytershteyn
Summary: A collisionless shock is a self-organized structure that adjusts fields and particle distributions to ensure stable mass, momentum, and energy transfer from the upstream to the downstream region. The motion of charged particles generates fields inside the shock front, which in turn governs the particle motion. The overshoot compensates for the deceleration of ion flow by increasing the magnetic field, adjusting downstream ion temperature and pressure, speeding up collisionless relaxation, and reducing anisotropy.
JOURNAL OF PLASMA PHYSICS
(2023)
Review
Astronomy & Astrophysics
Benjamin P. P. Weiss, Jose M. G. Merayo, Jodie B. B. Ream, Rona Oran, Peter Brauer, Corey J. J. Cochrane, Kyle Cloutier, Linda T. T. Elkins-Tanton, John L. L. Jorgensen, Clara Maurel, Ryan S. S. Park, Carol A. A. Polanskey, Maria de Soria Santacruz-Pich, Carol A. A. Raymond, Christopher T. T. Russell, Daniel Wenkert, Mark A. A. Wieczorek, Maria T. T. Zuber
Summary: The Psyche Magnetometry Investigation aims to test the hypothesis that asteroid (16) Psyche formed from a differentiated planetesimal. The instrument will measure the magnetic field around the asteroid to search for evidence of remanent magnetization. It consists of two three-axis fluxgate Sensor Units (SUs) mounted along a 2.15-m long boom, connected to Electronics Units (EUs) within the spacecraft bus. The Magnetometer will acquire data for the full duration of the mission to estimate Psyche's dipole moment.
SPACE SCIENCE REVIEWS
(2023)
Article
Astronomy & Astrophysics
N. Omidi, X. -Y. Zhou, C. T. Russell, V. Angelopoulos
Summary: In this study, the interaction between interplanetary shocks and the Moon is investigated using 3-D electromagnetic hybrid simulations and observations. The results show the formation and recovery of a density hole in the shock front on the Moon's dayside, as well as the broadening of the magnetic field shock front in the lunar tail. The interplanetary shock also accelerates energetic ions in the lunar tail. Comparisons between the measurements in the solar wind and lunar tail confirm the absence of a shock front in density and the expected broadening of the magnetic field profile.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Wenyi Sun, Yingjuan Ma, Christopher T. Russell, Janet Luhmann, Andrew Nagy, David Brain
Summary: Although photochemistry-enabled escape of oxygen is dominant at Mars today, ion outflow, including planetary proton loss, plays an important role in the atmosphere's long-term evolution. Improving the MHD model of Mars to differentiate between planetary and solar wind protons, we find that planetary proton escape rates exceed heavy ion loss rates and solar wind proton inflows. However, the contribution of planetary protons to hydrogen loss is limited. By considering different reactions, we conclude that H-O charge exchange affects low altitude densities while impact ionizations impact escape rates at higher altitudes. This research highlights the need to include specific treatment of proton origins in future studies on the fate of water on Mars.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
X. Tan, M. W. Dunlop, X. -c. Dong, Y. -y. Yang, Y. -s. Du, C. Shen, C. T. Russell, W. -l. Liu
Summary: We estimated the in situ current density of the Earth's ring current using the curlometer method and examined its morphology using the Magnetospheric Multiscale mission's high accuracy data. Statistical analysis of data from September 2015 to the end of 2016 revealed a near-equatorial morphology of the ring current in terms of radial distance and magnetic local time. We also discovered asymmetries in the inner and outer currents, suggesting peak and valley plasma pressure contributions.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Xing-Yu Li, Qiu-Gang Zong, Jian-Jun Liu, Ze-Fan Yin, Ze-Jun Hu, Xu-Zhi Zhou, Chao Yue, Zhi-Yang Liu, Xing-Xin Zhao, Zi-Kang Xie, J. Bernard Blake, Christopher T. Russell, Robert E. Ergun, Per-Arne Lindqvist
Summary: This study conducted a comparative research on two pulsating aurora events and ULF waves, and found a correlation between pulsating auroras and ULF waves. The physical mechanisms behind this correlation differ in different events. The ULF waves may originate from perturbations in the solar wind and play a significant role in the solar wind-magnetosphere-ionosphere coupling, but further study is needed.
Article
Astronomy & Astrophysics
Z. C. Tian, M. Zhou, H. Y. Man, Z. H. Zhong, X. H. Deng, D. J. Gershman, Y. V. Khotyaintsev, C. T. Russell
Summary: This paper presents the simultaneous observation of the inner and outer electron diffusion region (EDR) in magnetic reconnection with a large guide field at the dayside magnetopause by the magnetospheric multiscale (MMS) spacecraft. The inner EDR is characterized by positive J·E', while the outer EDR is manifested by negative J·E' and opposite out-of-plane electric field. The observation of bidirectional accelerated electron jets on the opposite side of the X-line is significant, and the fortuitous formation of MMS provides estimates for the length of the inner EDR and the reconnection rate.
ASTROPHYSICAL JOURNAL
(2023)
Article
Geosciences, Multidisciplinary
Tongkuai Li, Wenya Li, Binbin Tang, Yuri. V. Khotyaintsev, Daniel Bruce Graham, Akhtar Ardakani, J. L. Burch, D. J. Gershman, B. Lavraud, C. T. Russell, Quanming Lu, Xiaocheng Guo, Chi Wang
Summary: This study presents Magnetospheric Multiscale (MMS) observations of a K-H wave event accompanied by ongoing magnetic reconnection under southward IMF conditions. The nonlinear K-H waves exhibit quasi-periodic fluctuations, presence of low-density and high-speed ions, and variations in the boundary normal vectors. Through the identification of Alfvenic ion jets and the escape of energetic magnetospheric electrons, clear evidence of on-going magnetic reconnection is revealed. Notably, out of the 36 magnetopause current-sheet crossings in this event, 19 exhibit unambiguous signatures of reconnection at both the leading and trailing edges, indicating the compression effect resulting from the large-scale evolution of the K-H waves.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Physics, Fluids & Plasmas
Harry C. Lewis, Julia E. Stawarz, Luca Franci, Lorenzo Matteini, Kristopher Klein, Chadi S. Salem, James L. Burch, Robert E. Ergun, Barbara L. Giles, Christopher T. Russell, Per-Arne Lindqvist
Summary: Turbulence in space plasmas is analyzed using Magnetospheric Multiscale (MMS) measurements. Different linear and nonlinear processes are decomposed using the electric field dynamics measured by MMS. Spectral characteristics of the terms in generalized Ohm's law are identified, including the dominance of the Hall effect over MHD, constant amplitude ratio of electron pressure to Hall effect, and independent scaling of nonlinear and linear components. The findings provide insights into the relationship between fluctuation amplitudes and plasma conditions.
PHYSICS OF PLASMAS
(2023)
Article
Astronomy & Astrophysics
S. H. Lee, D. G. Sibeck, N. Omidi, M. V. D. Silveira, A. Vu, S. K. Vines, I. J. Cohen, S. A. Fuselier, H. Wei, C. T. Russell, J. L. Burch
Summary: Foreshock bubbles (FBs) are transient features that occur when interplanetary magnetic field discontinuities encounter the Earth's foreshock. These bubbles can accelerate ions through the Fermi acceleration process, and proton intensities inside FBs are greater than outside in a certain energy range.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
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.
