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24 results on '"Hannes Gröller"'

1. The Sloan Digital Sky Survey Reverberation Mapping Project: Key Results

Author

Yue Shen, Catherine J. Grier, Keith Horne, Zachary Stone, Jennifer I. Li, Qian Yang, Yasaman Homayouni, Jonathan R. Trump, Scott F. Anderson, W. N. Brandt, Patrick B. Hall, Luis C. Ho, Linhua Jiang, Patrick Petitjean, Donald P. Schneider, Charling Tao, Fergus. R. Donnan, Yusra AlSayyad, Matthew A. Bershady, Michael R. Blanton, Dmitry Bizyaev, Kevin Bundy, Yuguang Chen, Megan C. Davis, Kyle Dawson, Xiaohui Fan, Jenny E. Greene, Hannes Gröller, Yucheng Guo, Héctor Ibarra-Medel, Yuanzhe Jiang, Ryan P. Keenan, Juna A. Kollmeier, Cassandra Lejoly, Zefeng Li, Axel de la Macorra, Maxwell Moe, Jundan Nie, Graziano Rossi, Paul S. Smith, Wei Leong Tee, Anne-Marie Weijmans, Jiachuan Xu, Minghao Yue, Xu Zhou, Zhimin Zhou, and Hu Zou

Subjects
Reverberation mapping, Surveys, Quasars, Astrophysics, QB460-466
Abstract

We present the final data from the Sloan Digital Sky Survey (SDSS) Reverberation Mapping (RM) project, a precursor to the SDSS-V Black Hole Mapper RM program. This data set includes 11 yr photometric and 7 yr spectroscopic light curves for 849 broad-line quasars over a redshift range of 0.1 < z < 4.5 and a luminosity range of L _bol = 10 ^44−47.5 erg s ^−1 , along with spectral and variability measurements. We report 23, 81, 125, and 110 RM lags (relative to optical continuum variability) for broad H α , H β , Mg ii , and C iv using the SDSS-RM sample, spanning much of the luminosity and redshift ranges of the sample. Using 30 low-redshift RM active galactic nuclei with dynamical-modeling black hole masses, we derive a new estimate of the average virial factor of $\left\langle \mathrm{log}f\right\rangle =0.62\pm 0.07$ for the line dispersion measured from the rms spectrum. The intrinsic scatter of individual virial factors is 0.31 ± 0.07 dex, indicating a factor of 2 systematic uncertainty in RM black hole masses. Our lag measurements reveal significant R – L relations for H β and Mg ii at high redshift, consistent with the latest measurements based on heterogeneous samples. While we are unable to robustly constrain the slope of the R – L relation for C iv given the limited dynamic range in luminosity, we found substantially larger scatter in C iv lags at fixed L _1350 . Using the SDSS-RM lag sample, we derive improved single-epoch (SE) mass recipes for H β , Mg ii , and C iv , which are consistent with their respective RM masses as well as between the SE recipes from two different lines, over the luminosity range probed by our sample. The new H β and Mg ii recipes are approximately unbiased estimators at given RM masses, but there are systematic biases in the C iv recipe. The intrinsic scatter of SE masses around RM masses is ∼0.45 dex for H β and Mg ii , increasing to ∼0.58 dex for C iv .

Published
2024
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2. Photometry of the Didymos System across the DART Impact Apparition

Author

Nicholas Moskovitz, Cristina Thomas, Petr Pravec, Tim Lister, Tom Polakis, David Osip, Theodore Kareta, Agata Rożek, Steven R. Chesley, Shantanu P. Naidu, Peter Scheirich, William Ryan, Eileen Ryan, Brian Skiff, Colin Snodgrass, Matthew M. Knight, Andrew S. Rivkin, Nancy L. Chabot, Vova Ayvazian, Irina Belskaya, Zouhair Benkhaldoun, Daniel N. Berteşteanu, Mariangela Bonavita, Terrence H. Bressi, Melissa J. Brucker, Martin J. Burgdorf, Otabek Burkhonov, Brian Burt, Carlos Contreras, Joseph Chatelain, Young-Jun Choi, Matthew Daily, Julia de León, Kamoliddin Ergashev, Tony Farnham, Petr Fatka, Marin Ferrais, Stefan Geier, Edward Gomez, Sarah Greenstreet, Hannes Gröller, Carl Hergenrother, Carrie Holt, Kamil Hornoch, Marek Husárik, Raguli Inasaridze, Emmanuel Jehin, Elahe Khalouei, Jean-Baptiste Kikwaya Eluo, Myung-Jin Kim, Yurij Krugly, Hana Kučáková, Peter Kušnirák, Jeffrey A. Larsen, Hee-Jae Lee, Cassandra Lejoly, Javier Licandro, Penélope Longa-Peña, Ronald A. Mastaler, Curtis McCully, Hong-Kyu Moon, Nidia Morrell, Arushi Nath, Dagmara Oszkiewicz, Daniel Parrott, Liz Phillips, Marcel M. Popescu, Donald Pray, George Pantelimon Prodan, Markus Rabus, Michael T. Read, Inna Reva, Vernon Roark, Toni Santana-Ros, James V. Scotti, Taiyo Tatara, Audrey Thirouin, David Tholen, Volodymyr Troianskyi, Andrew F. Tubbiolo, and Katelyn Villa

Subjects
Near-Earth objects, Asteroids, Small Solar System bodies, Astronomy, QB1-991
Abstract

On 2022 September 26, the Double Asteroid Redirection Test (DART) spacecraft impacted Dimorphos, the satellite of binary near-Earth asteroid (65803) Didymos. This demonstrated the efficacy of a kinetic impactor for planetary defense by changing the orbital period of Dimorphos by 33 minutes. Measuring the period change relied heavily on a coordinated campaign of lightcurve photometry designed to detect mutual events (occultations and eclipses) as a direct probe of the satellite’s orbital period. A total of 28 telescopes contributed 224 individual lightcurves during the impact apparition from 2022 July to 2023 February. We focus here on decomposable lightcurves, i.e., those from which mutual events could be extracted. We describe our process of lightcurve decomposition and use that to release the full data set for future analysis. We leverage these data to place constraints on the postimpact evolution of ejecta. The measured depths of mutual events relative to models showed that the ejecta became optically thin within the first ∼1 day after impact and then faded with a decay time of about 25 days. The bulk magnitude of the system showed that ejecta no longer contributed measurable brightness enhancement after about 20 days postimpact. This bulk photometric behavior was not well represented by an HG photometric model. An HG _1 G _2 model did fit the data well across a wide range of phase angles. Lastly, we note the presence of an ejecta tail through at least 2023 March. Its persistence implied ongoing escape of ejecta from the system many months after DART impact.

Published
2024
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3. A Warm Layer in the Nightside Mesosphere of Mars

Author

Hiromu Nakagawa, Sonal K. Jain, Nicholas M. Schneider, Franck Montmessin, Roger V. Yelle, Fayu Jiang, Loic Verdier, Takeshi Kuroda, Nao Yoshida, Hitoshi Fujiwara, Takeshi Imamura, Naoki Terada, Kaori Terada, Kanako Seki, Hannes Gröller, and Justin I. Deighan

Subjects
Geophysics. Cosmic physics, QC801-809
Abstract

Abstract We report a new set of stellar occultation measurements for nightside temperature profiles made by the Mars Atmosphere and Volatile EvolutioN/Imaging Ultraviolet Spectrograph that provide evidence for a recurring layer of warm air between 70 and 90 km altitudes in the nightside mesosphere of Mars during Ls = 0–180° in Martian Year 33–34. The nightside profiles reveal a recurring peak of atmospheric temperature around 80 km over the equator to the middle latitudes in the northern hemisphere. The predictions of the Mars Climate Database have a warm layer with much smaller amplitudes. The observed peak amplitudes are larger than those predicted by the model by up to 90 K. Wavenumber‐3 structures are seen in the warm layer that are potentially signatures of thermal tides or stationary planetary waves, with amplitudes two times larger than predicted.

Published
2020
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5. A warm layer in the nightside mesosphere of Mars

Author

Kaori Terada, Naoki Terada, Fayu Jiang, Sonal Jain, Kanako Seki, Nao Yoshida, Takeshi Imamura, Hannes Gröller, Franck Montmessin, Justin Deighan, Takeshi Kuroda, Roger V. Yelle, Hitoshi Fujiwara, Hiromu Nakagawa, Nicholas M. Schneider, Loic Verdier, Graduate School of Information Sciences [Sendai], Tohoku University [Sendai], Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Faculty of Science and Technology [Tokyo], Seikei University, Graduate School of Frontier Sciences [Kashiwa], The University of Tokyo (UTokyo), and Graduate School of Science [Tokyo]

Subjects
010504 meteorology & atmospheric sciences, Equator, Northern Hemisphere, Mars Exploration Program, 010502 geochemistry & geophysics, Atmospheric sciences, Atmospheric temperature, 01 natural sciences, Mesosphere, Warm front, Geophysics, 13. Climate action, [SDU]Sciences of the Universe [physics], Middle latitudes, General Earth and Planetary Sciences, Timekeeping on Mars, Geology, 0105 earth and related environmental sciences
Abstract

International audience; We report a new set of stellar occultation measurements for nightside temperature profiles made by the MAVEN/IUVS that provide evidence for a recurring layer of warm air between 70‐90 km altitudes in the nightside mesosphere of Mars during Ls = 0° ‐ 180° in Martian Year 33‐34. The nightside profiles reveal a recurring peak of atmospheric temperature around 80 km over the equator to the middle latitudes in the northern hemisphere. The predictions of the Mars Climate Database have a warm layer with much smaller amplitudes. The observed peak amplitudes are larger than those predicted by the model by up to 90 K. Wavenumber‐3 structures are seen in the warm layer that are potentially signatures of thermal tides or stationary planetary waves, with amplitudes two‐times larger than predicted.

Published
2020
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6. Escape and evolution of Mars's CO2 atmosphere: Influence of suprathermal atoms

Author

Fuqiang Tian, Herbert Lichtenegger, Lena Noack, Manuel Scherf, Hannes Gröller, Ute Amerstorfer, L. Tu, Helmut Lammer, Manuel Güdel, and Colin P. Johnstone

Subjects
Physics, 010504 meteorology & atmospheric sciences, Atmosphere of Mars, Mars Exploration Program, 01 natural sciences, Astrobiology, Atmosphere, Geophysics, Space and Planetary Science, Geochemistry and Petrology, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

Austrian Science Fund (FWF) [P24247-N16, S11601-N16, S11604-N16, S11607-N16, S11606-N16]; Interuniversity Attraction Poles Programme

Published
2017
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7. Vertical propagation of wave perturbations in the middle atmosphere on Mars by MAVEN/IUVS

Author

Hitoshi Fujiwara, Takeshi Imamura, Fayu Jiang, Nao Yoshida, Nicholas M. Schneider, Kaori Terada, Naoki Terada, Kanako Seki, Sonal Jain, Loic Verdier, Justin Deighan, Hiromu Nakagawa, Hannes Gröller, Franck Montmessin, Bruce M. Jakosky, Roger V. Yelle, Scott L. England, Takeshi Kuroda, Graduate School of Information Sciences [Sendai], Tohoku University [Sendai], Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Department of Aerospace and Ocean Engineering [Blackburg], Virginia Polytechnic Institute and State University [Blacksburg], Graduate School of Science [Tokyo], The University of Tokyo (UTokyo), Faculty of Science and Technology [Tokyo], Seikei University, and Graduate School of Frontier Sciences [Kashiwa]

Subjects
Physics, Martian, 010504 meteorology & atmospheric sciences, Atmosphere of Mars, Astrophysics, Mars Exploration Program, 01 natural sciences, Mesosphere, Physics::Geophysics, Atmosphere, Geophysics, Amplitude, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, [SDU]Sciences of the Universe [physics], Spectral slope, Physics::Space Physics, Earth and Planetary Sciences (miscellaneous), Astrophysics::Earth and Planetary Astrophysics, Thermosphere, 0105 earth and related environmental sciences
Abstract

International audience; This work offers the first in‐depth study of the global characteristics of wave perturbations in temperature profiles at 20 ‐ 140 km altitudes derived from the Imaging Ultraviolet Spectrograph (IUVS) onboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft. The peak amplitudes of waves seen in temperature profiles exceed 20 % of the mean background, especially on the nightside, which is larger than those in Earth’s mesosphere and thermosphere. The wave perturbations generate an instability layer around 70‐100 km on the nightside, which potentially causes wave‐breaking and turbulences. Our results highlighted a seasonal variation in the latitudinal distribution of nightside perturbations. Amplitudes of wave perturbations were found to be large in the northern low‐latitude region and the southern polar region during the first half of the year (Ls = 0° ‐ 180°). An increase of waves in the spectral density was found in southern low‐latitude regions in the latter half of the year (Ls = 180° ‐ 360°). Vertical wavenumber spectral density in the Martian middle atmosphere shows a power‐law dependence with a logarithmic spectral slope of ‐3, similar to the features seen in the Earth’s atmosphere. The derived spectral power density suggests the longer waves growing with height while the effective dissipation of shorter waves occurs. The strong CO2 15‐micron band cooling can effectively dissipate shorter waves. In contrast, the spectral power density at longer waves suggests an amplitude growth with height of unsaturated waves up to the lower thermosphere.

Published
2020
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8. Hot oxygen and carbon escape from the martian atmosphere

Author

Helmut Lammer, Herbert Lichtenegger, Valery I. Shematovich, and Hannes Gröller

Subjects
Quenching, Earth and Planetary Astrophysics (astro-ph.EP), Materials science, Scattering, Photodissociation, chemistry.chemical_element, FOS: Physical sciences, Astronomy and Astrophysics, Atmosphere of Mars, 7. Clean energy, Oxygen, Ion, chemistry, 13. Climate action, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, Atomic physics, Carbon, Dissociative recombination, Astrophysics - Earth and Planetary Astrophysics
Abstract

The escape of hot O and C atoms from the present martian atmosphere during low and high solar activity conditions has been studied with a Monte-Carlo model. The model includes the initial energy distribution of hot atoms, elastic, inelastic, and quenching collisions between the suprathermal atoms and the ambient cooler neutral atmosphere, and applies energy dependent total and differential cross sections for the determination of the collision probability and the scattering angles. The results yield a total loss rate of hot oxygen of $2.3-2.9\times 10^{25}\,{\rm s}^{-1}$ during low and high solar activity conditions and is mainly due to dissociative recombination of O$_2^+$ and CO$_2^+$. The total loss rates of carbon are found to be $0.8$ and $3.2\times 10^{24}\,{\rm s}^{-1}$ for low and high solar activity, respectively, with photodissociation of CO being the main source. Depending on solar activity, the obtained carbon loss rates are up to $\sim 40$ times higher than the CO$_2^+$ ion loss rate inferred from Mars Express ASPERA-3 observations. Finally, collisional effects above the exobase reduce the escape rates by about $20-30\,\%$ with respect to a collionless exophere., 8 figures and 14 tables

Published
2019

9. Solar XUV and ENA-driven water loss from early Venus' steam atmosphere

Author

Nikolai V. Erkaev, Kristina G. Kislyakova, Hannes Gröller, Manuel Güdel, Mats Holmström, L. Tu, Colin P. Johnstone, Linda T. Elkins-Tanton, Petra Odert, Herbert Lichtenegger, and Helmut Lammer

Subjects
Materials science, 010504 meteorology & atmospheric sciences, Hydrogen, chemistry.chemical_element, Venus, 01 natural sciences, 7. Clean energy, Atmosphere, 0103 physical sciences, Thermal, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, biology, Atmospheric escape, biology.organism_classification, Solar wind, Geophysics, chemistry, 13. Climate action, Space and Planetary Science, Extreme ultraviolet, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, Atomic physics, Thermosphere
Abstract

The influence of the hydrogen hydrodynamic upper atmosphere escape, driven by the solar soft X-ray and extreme ultraviolet radiation (XUV) flux, on an expected magma ocean outgassed steam atmosphere of early Venus is studied. By assuming that the young Sun was either a weak or moderate active young G star, we estimated the water loss from a hydrogen dominated thermosphere due to the absorption of the solar XUV flux and the precipitation of solar wind produced energetic hydrogen atoms (ENAs). The production of ENAs and their interaction with the hydrodynamic extended upper atmosphere, including collision-related feedback processes, have been calculated by means of Monte Carlo models. ENAs that collide in the upper atmosphere deposit their energy and heat the surrounding gas mainly above the main XUV energy deposition layer. It is shown that precipitating ENAs modify the thermal structure of the upper atmosphere, but the enhancement of the thermal escape rates caused by these energetic hydrogen atoms is negligible. Our results also indicate that the majority of oxygen arising from dissociated H$_2$O molecules is left behind during the first 100 Myr. It is thus suggested that the main part of the remaining oxygen has been absorbed by crustal oxidation.

Published
2016
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11. Detection of Mesospheric CO2 Ice Clouds on Mars in Southern Summer

Author

Loic Verdier, Nicholas M. Schneider, Hannes Gröller, Franck Montmessin, Sonal Jain, Fayu Jiang, Jun Cui, Roger V. Yelle, Justin Deighan, Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, CAS Key Laboratory of Lunar and Deep Space Exploration, Chinese Academy of Sciences [Beijing] (CAS), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Space and Atmospheric Physics Group [London], Blackett Laboratory, Imperial College London-Imperial College London, School of Atmospheric Sciences [Zhuhai], Sun Yat-Sen University [Guangzhou] (SYSU), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), and Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
010504 meteorology & atmospheric sciences, Mie scattering, Atmosphere of Mars, Mars Exploration Program, 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, Spectral line, Geophysics, Altitude, 13. Climate action, Extinction (optical mineralogy), [SDU]Sciences of the Universe [physics], Physics::Space Physics, General Earth and Planetary Sciences, Astrophysics::Earth and Planetary Astrophysics, Longitude, Spectrograph, Geology, Astrophysics::Galaxy Astrophysics, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences
Abstract

International audience; This paper reports the first detections of two high‐altitude nighttime CO2 clouds on Mars during southern summer (Ls = 264° and Ls = 330°) with stellar occultation measurements by the Imaging Ultraviolet Spectrograph on board the Mars Atmosphere and Volatile Evolution spacecraft. Interpretation of the transmission spectra with Mie theory indicates particle radii of ~90‐110 nm assuming a mono‐disperse distribution. The altitude profile of extinction indicates that the cloud layers are confined horizontally to sizes less than ~ 500‐700~km. Examination of the CO2 density and temperature profiles reveals strong wave‐like perturbations. Supersaturated temperatures occur at the maximum negative extent of these wave‐like perturbations, which are organized in longitude with a dominant m=3 zonal harmonic. This suggests that tides are important in the formation of CO2 clouds.

Published
2019
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12. MAVEN/IUVS Stellar Occultation Measurements of Mars Atmospheric Structure and Composition

Author

Tommi Koskinen, Justin Deighan, Nicholas M. Schneider, Roger V. Yelle, Hannes Gröller, Franck Montmessin, François Forget, Franck Lefèvre, Sonal Jain, Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], 010504 meteorology & atmospheric sciences, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Atmosphere of Mars, Mars Exploration Program, Atmospheric sciences, 01 natural sciences, Occultation, Latitude, Atmosphere, Geophysics, Altitude, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), Environmental science, Variation (astronomy), Longitude, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

International audience; The Imaging UltraViolet Spectrograph (IUVS) instrument of the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission has acquired data on Mars for more than one Martian year. During this time, beginning with March 2015, hundreds of stellar occultations have been observed, in 12 dedicated occultation campaigns, executed on average every two to three months. The occultations cover the latitudes from 80° S to 75° N and the full range longitude, and local times with relatively sparse sampling. From these measurements we retrieve CO2, O2, and O3 number densities as well as temperature profiles in the altitude range from 20 to 160 km, covering eight order of magnitudes in pressure from ∼2 × 101 to ∼4 × 10−7 Pa. These data constrain the composition and thermal structure of the atmosphere. The O2 mixing ratios retrieved during this study show a high variability from 1.5 × 10−3 to 6 × 10−3; however, the mean value seems to be constant with solar longitude. We detect ozone between 20 and 60 km. In many profiles there is a well defined peak between 30 and 40 km with a maximum density of 1 – 2 × 109 cm−3. Examination of the vertical temperature profiles reveals substantial disagreement with models, with observed temperatures both warmer and colder than predicted. Examination of the altitude profiles of density perturbations and their variation with longitude shows structured atmospheric perturbations at altitudes above 100 km that are likely non‐migrating tides. These perturbations are dominated by zonal wavenumber 2 and 3 with amplitudes greater than 45 %.

Published
2018
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13. The Kelvin–Helmholtz instability at Venus: What is the unstable boundary?

Author

Daniil Korovinskiy, U. V. Möstl, Helfried K. Biernat, Nikolay Erkaev, Michael Zellinger, Hannes Gröller, and Helmut Lammer

Subjects
Solar System, 010504 meteorology & atmospheric sciences, Solar wind, Venus, Astrophysics, 01 natural sciences, Instability, Article, 0103 physical sciences, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, biology, Astronomy and Astrophysics, Mechanics, biology.organism_classification, Vortex, Boundary layer, Magnetospheres, Space and Planetary Science, Physics::Space Physics, Magnetopause, Astrophysics::Earth and Planetary Astrophysics, Magnetohydrodynamics
Abstract

Highlights ► We study the Kelvin–Helmholtz instability at boundary layers around of Venus. ► The stability of the induced magnetopause and the ionopause is examined. ► The ionopause seems to be stable due to a large density jump across this boundary. ► The instability evolves into its nonlinear phase on the magnetopause at solar maximum. ► Loss rates are therefore lower than previously assumed., The Kelvin–Helmholtz instability gained scientific attention after observations at Venus by the spacecraft Pioneer Venus Orbiter gave rise to speculations that the instability contributes to the loss of planetary ions through the formation of plasma clouds. Since then, a handful of studies were devoted to the Kelvin–Helmholtz instability at the ionopause and its implications for Venus. The aim of this study is to investigate the stability of the two instability-relevant boundary layers around Venus: the induced magnetopause and the ionopause. We solve the 2D magnetohydrodynamic equations with the total variation diminishing Lax–Friedrichs algorithm and perform simulation runs with different initial conditions representing the situation at the boundary layers around Venus. Our results show that the Kelvin–Helmholtz instability does not seem to be able to reach its nonlinear vortex phase at the ionopause due to the very effective stabilizing effect of a large density jump across this boundary layer. This seems also to be true for the induced magnetopause for low solar activity. During high solar activity, however, there could occur conditions at the induced magnetopause which are in favour of the nonlinear evolution of the instability. For this situation, we estimated roughly a growth rate for planetary oxygen ions of about 7.6 × 1025 s−1, which should be regarded as an upper limit for loss due to the Kelvin–Helmholtz instability.

Published
2011
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14. Exospheres and Energetic Neutral Atoms of Mars, Venus and Titan

Author

Herbert Lichtenegger, Magda Delva, Jean-Yves Chaufray, Yoshifumi Futaana, H. Todd Smith, Hannes Gröller, Alessandro Mura, Philippe Garnier, Swedish Institute of Space Physics [Kiruna] (IRF), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), CNRS, UMR5187, F-31028 Toulouse, France, Institut für Weltraumforschung = Space Research institute [Graz] (IWF), Osterreichische Akademie der Wissenschaften (ÖAW), Istituto di Fisica dello Spazio Interplanetario (IFSI), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Institut für Weltraumforschung [Graz] (IWF), and Consiglio Nazionale delle Ricerche (CNR)

Subjects
Physics, 010504 meteorology & atmospheric sciences, biology, Energetic neutral atom, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Astronomy and Astrophysics, Venus, Mars Exploration Program, biology.organism_classification, 01 natural sciences, 7. Clean energy, Astrobiology, Atmosphere, symbols.namesake, Planetary science, 13. Climate action, Space and Planetary Science, Planet, 0103 physical sciences, symbols, Titan (rocket family), 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Exosphere
Abstract

International audience; Our understanding of the upper atmosphere of unmagnetized bodies such as Mars, Venus and Titan has improved significantly in this decade. Recent observations by in situ and remote sensing instruments on board Mars Express, Venus Express and Cassini have revealed characteristics of the neutral upper atmospheres (exospheres) and of energetic neutral atoms (ENAs). The ENA environment in the vicinity of the bodies is by itself a significant study field, but ENAs are also used as a diagnostic tool for the exosphere and the interaction with the upstream plasmas. Synergy between theoretical and modeling work has also improved considerably. In this review, we summarize the recent progress of our understanding of the neutral environment in the vicinity of unmagnetized planets.

Published
2011
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15. MAVEN observations of the response of Mars to an interplanetary coronal mass ejection

Author

Jane L. Fox, Joseph M. Grebowsky, D. Larson, Edward Thiemann, François Leblanc, Ali Rahmati, R. M. Dewey, Justin Deighan, Michael Chaffin, Valeriy Tenishev, Jasper Halekas, P. Dunn, A. F. Nagy, Mehdi Benna, Stephen W. Bougher, Arnaud Stiepen, Michael R. Combi, Yingjuan Ma, Yaxue Dong, Chuanfei Dong, Scott D. Guzewich, Richard W. Zurek, Daniel N. Baker, S. Stone, Roberto Livi, D. Baird, Robert Lillis, W. K. Peterson, D. W. Curtis, Tristan Weber, Scott Evans, R. Tolson, Glyn Collinson, William E. McClintock, K. Fortier, Christina O. Lee, Gregory T. Delory, John Clarke, Ronan Modolo, Janet G. Luhmann, Sonal Jain, T. McEnulty, Xiaohua Fang, Jared Espley, Nicholas M. Schneider, John E. P. Connerney, Laila Andersson, Paul Withers, David Andrews, Majd Mayyasi, Daniel Lo, Marissa F. Vogt, David Brain, Kirk Olsen, Y.-Y. Chaufray, Christopher T. Russell, Anders Eriksson, Bruce M. Jakosky, Meredith Elrod, Yuni Lee, Takuya Hara, Paul Mahaffy, Phillip C. Chamberlin, Michiko Morooka, Frank Eparvier, Thomas E. Cravens, Christopher M. Fowler, Kanako Seki, Robert E. Ergun, Scott L. England, Gina A. DiBraccio, A. I. F. Stewart, D. F. Mitchell, J. P. McFadden, Gregory M. Holsclaw, Yuki Harada, F. J. Crary, Matthew Fillingim, Hannes Gröller, Shannon Curry, Franck Montmessin, Matteo Crismani, D. Toublanc, Franck Lefèvre, Christian Mazelle, J. A. Sauvaud, Thomas N. Woods, Roger V. Yelle, Suranga Ruhunusiri, R. Jolitz, Jared Bell, M. Steckiewicz, Michael L. Stevens, Shotaro Sakai, Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], NASA Goddard Space Flight Center (GSFC), Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, Department of Physics and Astronomy [Ames, Iowa], Iowa State University (ISU), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Department of Climate and Space Sciences and Engineering (CLaSP), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Institute of Geophysics and Planetary Physics [Los Angeles] (IGPP), University of California [Los Angeles] (UCLA), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Swedish Institute of Space Physics [Uppsala] (IRF), NASA Johnson Space Center (JSC), NASA, National Institute of Aerospace [Hampton] (NIA), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Center for Space Physics [Boston] (CSP), Boston University [Boston] (BU), Department of Physics and Astronomy [Lawrence Kansas], University of Kansas [Lawrence] (KU), Computational Physics, Inc., Department of Physics [Dayton], Wright State University, Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, PLANETO - LATMOS, Department of Astronomy [Boston], Solar-Terrestrial Environment Laboratory [Nagoya] (STEL), Nagoya University, Naval Research Laboratory (NRL), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Multidisciplinary, Secondary atmosphere, 010504 meteorology & atmospheric sciences, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Atmosphere of Mars, Mars Exploration Program, 01 natural sciences, Astrobiology, Atmosphere, Solar wind, Magnetosheath, 13. Climate action, 0103 physical sciences, Physics::Space Physics, Astrophysics::Solar and Stellar Astrophysics, Bow shock (aerodynamics), Astrophysics::Earth and Planetary Astrophysics, Ionosphere, 010303 astronomy & astrophysics, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences
Abstract

International audience; Coupling between the lower and upper atmosphere, combined with loss of gas from the upper atmosphere to space, likely contributed to the thin, cold, dry atmosphere of modern Mars. To help understand ongoing ion loss to space, the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft made comprehensive measurements of the Mars upper atmosphere, ionosphere, and interactions with the Sun and solar wind during an interplanetary coronal mass ejection impact in March 2015. Responses include changes in the bow shock and magnetosheath, formation of widespread diffuse aurora, and enhancement of pick-up ions. Observations and models both show an enhancement in escape rate of ions to space during the event. Ion loss during solar events early in Mars history may have been a major contributor to the long-term evolution of the Mars atmosphere.

Published
2015
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16. Early MAVEN Deep Dip campaign reveals thermosphere and ionosphere variability

Author

J. M. Grebowsky, F. Leblanc, Suranga Ruhunusiri, John E. P. Connerney, Xiaohua Fang, Ronan Modolo, Scott D. Guzewich, Richard W. Zurek, Arnaud Stiepen, Michael R. Combi, Davin Larson, Christopher T. Russell, Anders Eriksson, M. Steckiewicz, Yaxue Dong, Franck Lefèvre, Christian Mazelle, J. A. Sauvaud, P. Dunn, Jane L. Fox, Shotaro Sakai, Chuanfei Dong, Yingjuan Ma, S. W. Bougher, S. Stone, R. Jolitz, Gregory M. Holsclaw, T. McEnulty, William E. McClintock, Kirk Olsen, Yuki Harada, A. F. Nagy, Robert Lillis, Thomas N. Woods, Michael L. Stevens, Sonal Jain, Jasper Halekas, Hannes Gröller, Shannon Curry, Franck Montmessin, D. W. Curtis, Tristan Weber, Kanako Seki, Christina O. Lee, Glyn Collinson, Takuya Hara, Paul Mahaffy, D. Baird, Scott L. England, D. Toublanc, Matteo Crismani, Roger V. Yelle, Gina A. DiBraccio, W. K. Peterson, R. M. Dewey, J. P. McFadden, Jared Bell, F. J. Crary, David Brain, Ali Rahmati, Matthew Fillingim, Janet G. Luhmann, John Clarke, Meredith Elrod, Bruce M. Jakosky, Nicholas M. Schneider, A. I. F. Stewart, Paul Withers, Majd Mayyasi, Thomas E. Cravens, Marissa F. Vogt, Edward Thiemann, Michael Chaffin, Phillip C. Chamberlin, Jean-Yves Chaufray, Daniel N. Baker, G. T. Delory, Laila Andersson, Jared Espley, Justin Deighan, Daniel Lo, Christopher M. Fowler, Valeriy Tenishev, Robert E. Ergun, Roberto Livi, Robert H. Tolson, David L. Mitchell, Scott Evans, Michiko Morooka, K. Fortier, Mehdi Benna, Frank Eparvier, David Andrews, Yuni Lee, Department of Climate and Space Sciences and Engineering (CLaSP), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Department of Physics and Astronomy [Ames, Iowa], Iowa State University (ISU), NASA Goddard Space Flight Center (GSFC), Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Swedish Institute of Space Physics [Uppsala] (IRF), NASA Johnson Space Center (JSC), NASA, National Institute of Aerospace [Hampton] (NIA), HELIOS - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Astronomy [Boston], Boston University [Boston] (BU), Department of Physics and Astronomy [Lawrence Kansas], University of Kansas [Lawrence] (KU), Computational Physics, Inc., Department of Physics [Dayton], Wright State University, Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, PLANETO - LATMOS, Institute of Geophysics and Planetary Physics [Los Angeles] (IGPP), University of California [Los Angeles] (UCLA), Solar-Terrestrial Environment Laboratory [Nagoya] (STEL), Nagoya University, Naval Research Laboratory (NRL), University of California [Berkeley], University of California-University of California, Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Martian, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Multidisciplinary, 010504 meteorology & atmospheric sciences, Atmospheric escape, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Atmosphere of Mars, Atmospheric sciences, 01 natural sciences, Physics::Geophysics, Atmosphere, Altitude, 13. Climate action, Extreme ultraviolet, 0103 physical sciences, Physics::Space Physics, Environmental science, Astrophysics::Earth and Planetary Astrophysics, Thermosphere, Ionosphere, 010303 astronomy & astrophysics, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences
Abstract

International audience; The Mars Atmosphere and Volatile Evolution (MAVEN) mission, during the second of its Deep Dip campaigns, made comprehensive measurements of martian thermosphere and ionosphere composition, structure, and variability at altitudes down to ~130 kilometers in the subsolar region. This altitude range contains the diffusively separated upper atmosphere just above the well-mixed atmosphere, the layer of peak extreme ultraviolet heating and primary reservoir for atmospheric escape. In situ measurements of the upper atmosphere reveal previously unmeasured populations of neutral and charged particles, the homopause altitude at approximately 130 kilometers, and an unexpected level of variability both on an orbit-to-orbit basis and within individual orbits. These observations help constrain volatile escape processes controlled by thermosphere and ionosphere structure and variability.

Published
2015
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17. Altitude profiles of O2 on Mars from SPICAM stellar occultations

Author

Eric Quémerais, Nikole K. Lewis, Hannes Gröller, Franck Montmessin, Tommi Koskinen, Bill R. Sandel, Roger V. Yelle, Jean-Loup Bertaux, Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Department of Earth, Atmospheric and Planetary Sciences [MIT, Cambridge] (EAPS), Massachusetts Institute of Technology (MIT), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and HELIOS - LATMOS

Subjects
Atmospheres, Secondary atmosphere, Stellar occultations, Aeronomy, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Mars, Astronomy and Astrophysics, Atmosphere of Mars, Astrophysics, Mars Exploration Program, Ultraviolet observations, Atmospheric sciences, Atmosphere, Stars, Altitude, 13. Climate action, Space and Planetary Science, composition, atmosphere, Mixing ratio, Environmental science
Abstract

International audience; We determine the first altitude profiles of O2 in the important photochemical region below 120 km in the atmosphere of Mars by analyzing Mars Express/SPICAM ultraviolet observations of six occultations of stars by the atmosphere. Over the range of 90–130 km the altitude-averaged mixing ratio of O2 relative to the major constituent CO2 varies in space and time in the range of 3.1×10-3 to 5.8×10-3, with a mean value of 4.0×10-3. This mean value exceeds by a factor of 3–4 those reported earlier for the lower atmosphere. However, some of the O2 abundance and mixing ratio profiles determined here are similar to those measured by Viking in 1976 in the upper atmosphere.

Published
2015
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18. Probing the Martian atmosphere with MAVEN/IUVS stellar occultations

Author

William E. McClintock, Nicholas M. Schneider, S. W. Bougher, Matteo Crismani, Gaetan Lacombe, Justin Deighan, Michael Chaffin, A. I. F. Stewart, Roger V. Yelle, Arnaud Stiepen, Paul R. Mahaffy, Gregory M. Holsclaw, Hannes Gröller, Franck Montmessin, Sonal Jain, Bruce M. Jakosky, John Clarke, Franck Lefèvre, Tommi Koskinen, Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Center for Space Physics [Boston] (CSP), Boston University [Boston] (BU), NASA Goddard Space Flight Center (GSFC), Department of Atmospheric, Oceanic, and Space Sciences [Ann Arbor] (AOSS), University of Michigan [Ann Arbor], and University of Michigan System-University of Michigan System

Subjects
010504 meteorology & atmospheric sciences, Terminator (solar), [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Mars, 01 natural sciences, Astrobiology, Atmosphere, Planet, 0103 physical sciences, Stellar Occultation, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Temperature, Astronomy, Atmosphere of Mars, Mars Exploration Program, IUVS/MAVEN, Geophysics, Atmosphere of Earth, 13. Climate action, CO2 and O2 Density, General Earth and Planetary Sciences, Ionosphere, Thermosphere
Abstract

International audience; The first campaign of stellar occultations with the Imaging Ultraviolet Spectrograph (IUVS) instrument on board of Mars Atmosphere and Volatile EvolutioN (MAVEN) mission was executed between 24 and 26 March 2015. From this campaign 13 occultations are used to retrieve CO2 and O2 number densities in the altitude range between 100 and 150 km. Observations probe primarily the low-latitude regions on the nightside of the planet, just past the dawn and dusk terminator. Calculation of temperature from the CO2 density profiles reveals that the lower thermosphere is significantly cooler than predicted by the models in the Mars Climate Database. A systematically cold layer with temperatures of 105–120 K is seen in the occultations at a pressure level around 7 × 10−6 Pa.

Published
2015
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19. Outgassing History and Escape of the Martian Atmosphere and Water Inventory

Author

Matthias Grott, Eric Chassefière, Achim Morschhauser, Doris Breuer, Véronique Dehant, Lê Binh San Pham, Hannes Gröller, Petra Odert, Olivier Mousis, Özgür Karatekin, Helmut Lammer, Paul B. Niles, Ernst Hauber, and U. V. Möstl

Subjects
010504 meteorology & atmospheric sciences, Thermal escape, Amazonian, Early Mars, Atmospheric evolution, FOS: Physical sciences, 01 natural sciences, Astrobiology, Young Sun, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Volcanic outgassing, Nonthermal escape, 010303 astronomy & astrophysics, Physics::Atmospheric and Oceanic Physics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), Magma ocean, Secondary atmosphere, Atmospheric escape, Noachian, Astronomy and Astrophysics, Mars Exploration Program, Atmosphere of Mars, Outgassing, 13. Climate action, Space and Planetary Science, Impacts, Hesperian, Astrophysics::Earth and Planetary Astrophysics, Geology, Astrophysics - Earth and Planetary Astrophysics
Abstract

The evolution and escape of the martian atmosphere and the planet's water inventory can be separated into an early and late evolutionary epoch. The first epoch started from the planet's origin and lasted $\sim$500 Myr. Because of the high EUV flux of the young Sun and Mars' low gravity it was accompanied by hydrodynamic blow-off of hydrogen and strong thermal escape rates of dragged heavier species such as O and C atoms. After the main part of the protoatmosphere was lost, impact-related volatiles and mantle outgassing may have resulted in accumulation of a secondary CO$_2$ atmosphere of a few tens to a few hundred mbar around $\sim$4--4.3 Gyr ago. The evolution of the atmospheric surface pressure and water inventory of such a secondary atmosphere during the second epoch which lasted from the end of the Noachian until today was most likely determined by a complex interplay of various nonthermal atmospheric escape processes, impacts, carbonate precipitation, and serpentinization during the Hesperian and Amazonian epochs which led to the present day surface pressure., 49 pages, 14 figures

Published
2013

20. Hot oxygen atoms in the Venus nightside exosphere

Author

Helfried K. Biernat, M. Pfleger, Yu. N. Kulikov, Odile Dutuit, Valery I. Shematovich, Helmut Lammer, Hannes Gröller, and Herbert Lichtenegger

Subjects
Materials science, biology, Scattering, chemistry.chemical_element, Venus, biology.organism_classification, Oxygen, Ion, Geophysics, chemistry, Physics::Space Physics, Physics::Atomic and Molecular Clusters, General Earth and Planetary Sciences, Astrophysics::Earth and Planetary Astrophysics, Atomic physics, Ionosphere, Dissociative recombination, Excitation, Exosphere
Abstract

[1] The nightside oxygen exosphere of Venus is investigated for high and moderate solar activity by means of a Monte-Carlo model. Hot O atoms are assumed to be produced by dissociative recombination of O2+ and NO+ molecular ions and by charge transfer processes between ionospheric O+ ions and neutral O and H atoms. The model considers rotational and vibrational excitation of the initial energy distribution of hot O atoms, includes elastic, inelastic, and quenching collisions between the suprathermal atoms and the ambient neutral atmosphere species, and uses differential cross sections for the determination of the scattering angle in the collisions. The results indicate that dissociative recombination of O2+ is, like at Venus' dayside, the most efficient source of hot O atoms at the planet's nightside. For high solar activity, the nightside exospheric density of hot O atoms is about one order of magnitude lower compared to the dayside, although between 2–10 times higher than in previous studies.

Published
2012
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21. Venus' atomic hot oxygen environment

Author

Valery I. Shematovich, Wolfgang Macher, Helmut Lammer, Helfried K. Biernat, M. Pfleger, Ute Amerstorfer, Yu. N. Kulikov, Hannes Gröller, and Herbert Lichtenegger

Subjects
Atmospheric Science, Soil Science, Venus, Aquatic Science, Inelastic scattering, Oceanography, Atmosphere, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Astrophysics::Solar and Stellar Astrophysics, Earth-Surface Processes, Water Science and Technology, Quenching, Physics, Ecology, biology, Scattering, Paleontology, Forestry, biology.organism_classification, Corona, Geophysics, Space and Planetary Science, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, Hot particle, Atomic physics, Excitation
Abstract

[1] We present a Monte Carlo study of the atomic hot oxygen corona of Venus. In this model we consider elastic, inelastic, and quenching collisions between the traced hot particle and the ambient neutral atmosphere as well as differential cross sections to determine the scattering angle in the collisions. We also include rotational and vibrational excitation energies for the calculation of the initial energy of the produced hot oxygen atoms. Our results indicate that the differential cross sections and the fraction between elastic, inelastic, and quenching collisions are the most sensitive parameters which effect the corona density. We found that the hot O densities inferred from PVO observations can only be reproduced during high solar activity based on a forward scattering model but without inelastic and quenching collisions. The corona densities for low solar activity (VEX solar conditions) are about a factor of 2–3 smaller than for high solar activity.

Published
2010
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22. Geophysical and atmospheric evolution of habitable planets

Author

Günter Stangl, Glenn J. White, Thomas Henning, Doris Breuer, W. Hausleitner, Helfried K. Biernat, Jean-Mathias Grießmeier, Andreas Quirrenbach, Jonathan I. Lunine, Hannes Gröller, Eric Chassefière, Tom Herbst, Charles Beichman, Yuri N. Kulikov, Richard Lundin, Alan J. Penny, Herbert Lichtenegger, René Liseau, Uwe Motschmann, Helmut Lammer, Carlos Eiroa, Lisa Kaltenegger, Francesco Paresce, Tilman Spohn, Petra Odert, John Parnell, François Leblanc, Heike Rauer, Nikolai V. Erkaev, Esa Kallio, A. Stadelmann, Jean Schneider, Huub Röttgering, Martin Leitzinger, Maxim L. Khodachenko, Alain Léger, Arnold Hanslmeier, Giovanna Tinetti, Siegfried J. Bauer, William C. Danchi, Frances Westall, Malcolm Fridlund, Daphne Stam, Franck Selsis, Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Interactions et dynamique des environnements de surface (IDES), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Netherlands Institute for Radio Astronomy (ASTRON), Polar Geophysical Institute of Russian Academy of Sciences (PGI), Russian Academy of Sciences [Moscow] (RAS), Institute of Computational Modelling of the Russian Academy of Sciences (ICM SB RAS), Siberian Branch of the Russian Academy of Sciences (SB RAS), Finnish Meteorological Institute (FMI), Swedish Institute of Space Physics [Kiruna] (IRF), Centre de biophysique moléculaire (CBM), Université d'Orléans (UO)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Institute of Physics [Graz], Karl-Franzens-Universität [Graz, Autriche], NASA ExoPlanet Science Institute (NExScI), California Institute of Technology (CALTECH), NASA Goddard Space Flight Center (GSFC), Universidad Autonoma de Madrid (UAM), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA)-European Space Agency (ESA), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, Institut d'astrophysique spatiale (IAS), Department of Radio and Space Science [Göteborg], Chalmers University of Technology [Göteborg], Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Institut für Theoretische Physik [Braunschweig], Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Istituto Nazionale di Astrofisica (INAF), Department of Geology and Petroleum Geology [Aberdeen], University of Aberdeen, STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC), Landessternwarte Königstuhl [ZAH] (LSW), Universität Heidelberg [Heidelberg], Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Observatoire de Paris - Site de Meudon (OBSPM), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), SRON Netherlands Institute for Space Research (SRON), University College of London [London] (UCL), Department of Physics and Astronomy [Milton Keynes], The Open University [Milton Keynes] (OU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université d'Orléans (UO)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Karl-Franzens-Universität Graz, Universidad Autónoma de Madrid (UAM), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Harvard University-Smithsonian Institution, Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Universität Heidelberg [Heidelberg] = Heidelberg University, and Universiteit Leiden

Subjects
010504 meteorology & atmospheric sciences, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Kepler-69c, Habitability, Rare Earth hypothesis, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Planets, Environment, 01 natural sciences, Astrobiology, Physics::Geophysics, Eccentric Jupiter, Magnetics, Galactic habitable zone, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Terrestrial planets, 010303 astronomy & astrophysics, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, Radiation, Planetary habitability, Atmosphere, Astronomy, Water, Geophysics, Agricultural and Biological Sciences (miscellaneous), Habitability of orange dwarf systems, Earth analog, 13. Climate action, Space and Planetary Science, Atmosphere evolution, Terrestrial planet, Astrophysics::Earth and Planetary Astrophysics, Evolution, Planetary, Geology
Abstract

International audience; The evolution of Earth-like habitable planets is a complex process that depends on the geodynamical and geophysical environments. In particular, it is necessary that plate tectonics remain active over billions of years. These geophysically active environments are strongly coupled to a planet's host star parameters, such as mass, luminosity and activity, orbit location of the habitable zone, and the planet's initial water inventory. Depending on the host star's radiation and particle flux evolution, the composition in the thermosphere, and the availability of an active magnetic dynamo, the atmospheres of Earth-like planets within their habitable zones are differently affected due to thermal and nonthermal escape processes. For some planets, strong atmospheric escape could even effect the stability of the atmosphere

Published
2010
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23. On the elusive hot oxygen corona of Venus

Author

Herbert Lichtenegger, Yu. N. Kulikov, Helmut Lammer, Valery I. Shematovich, and Hannes Gröller

Subjects
Physics, Daytime, biology, Monte Carlo method, Venus, biology.organism_classification, Geophysics, Physics::Space Physics, General Earth and Planetary Sciences, Corona (planetary geology), Astrophysics::Earth and Planetary Astrophysics, Test particle, Thermosphere, Atomic physics, Dissociative recombination, Exosphere
Abstract

[1] After more than two years in orbit still no Venus Express observations were published concerning the hot oxygen corona of Venus which could verify the corresponding controversial observations of Venera 11 and PVO, three decades ago. Based on recent energy and mass dependent collision cross sections, the energy distributions of hot atomic oxygen created via dissociative recombination of O2+ are calculated in the daytime thermosphere by means of a 3D Monte Carlo approach. The exosphere density is obtained from the corresponding energy density and angular distribution at 240 km altitude by using a test particle model which traces the ballistic trajectories of hot O atoms in the exosphere. Our study indicates that upon taking into account proper input parameters, the hot oxygen corona appears to be substantially less dense than suggested by previous simulations.

Published
2009
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24. Variability of solar/stellar activity and magnetic field and its influence on planetary atmosphere evolution

Author

Manuel Güdel, Maxim L. Khodachenko, Bibiana Fichtinger, Herbert Lichtenegger, Malcolm Fridlund, Kristina G. Kislyakova, Helmut Lammer, Hannes Gröller, Sandro Krauss, Dmitry Bisikalo, Mats Holmström, Teimuraz V. Zaqarashvili, Yuri N. Kulikov, W. Hausleitner, Arnold Hanslmeier, Martin Leitzinger, Petra Odert, Heike Rauer, Ignasi Ribas, Valery I. Shematovich, and Jorge Sanz-Forcada

Subjects
Solar System, 010504 meteorology & atmospheric sciences, WSO-UV, atmosphere evolution, 01 natural sciences, Astrobiology, Atmosphere, Young Sun, Planet, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, solar proxies, Secondary atmosphere, Energetic neutral atom, Astronomy, Geology, Mars Exploration Program, Exoplanet, Solar wind, PLATO ​, solar wind, 13. Climate action, Space and Planetary Science, ENAs, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, solar activity
Abstract

It is shown that the evolution of planetary atmospheres can only be understood if one recognizes the fact that the radiation and particle environment of the Sun or a planet’s host star were not always on the same level as at present. New insights and the latest observations and research regarding the evolution of the solar radiation, plasma environment and solar/stellar magnetic field derived from the observations of solar proxies with different ages will be given. We show that the extreme radiation and plasma environments of the young Sun/stars have important implications for the evolution of planetary atmospheres and may be responsible for the fact that planets with low gravity like early Mars most likely never build up a dense atmosphere during the first few 100 Myr after their origin. Finally we present an innovative new idea on how hydrogen clouds and energetic neutral atom (ENA) observations around transiting Earth-like exoplanets by space observatories such as the WSO-UV, can be used for validating the addressed atmospheric evolution studies. Such observations would enhance our understanding on the impact on the activity of the young Sun on the early atmospheres of Venus, Earth, Mars and other Solar System bodies as well as exoplanets.

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