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16 results on '"Milby, Zachariah"'

1. JWST Spectrophotometry of the Small Satellites of Uranus and Neptune

Author

Belyakov, Matthew, Davis, M. Ryleigh, Milby, Zachariah, Wong, Ian, and Brown, Michael E.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

We use 1.4-4.6 micron multi-band photometry of the small inner Uranian and Neptunian satellites obtained with the James Webb Space Telescope's near-infrared imager NIRCam to characterize their surface compositions. We find that the satellites of the ice giants have, to first-order, similar compositions to one another, with a 3.0 micron absorption feature possibly associated with an O-H stretch, indicative of water ice or hydrated minerals. Additionally, the spectrophotometry for the small ice giant satellites matches spectra of some Neptune Trojans and excited Kuiper belt objects, suggesting shared properties. Future spectroscopy of these small satellites is necessary to identify and better constrain their specific surface compositions., Comment: 14 pages, 5 figures, Accepted to the Planetary Science Journal

Published
2024

2. The Optical Aurorae of Europa, Ganymede and Callisto

Author

de Kleer, Katherine, Milby, Zachariah, Schmidt, Carl, Camarca, Maria, and Brown, Michael E.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

The tenuous atmospheres of the Galilean satellites are sourced from their surfaces and produced by a combination of plasma-surface interactions and thermal processes. Though thin, these atmospheres can be studied via their auroral emissions, and most work to date has focused on their aurora at UV wavelengths. Here we present the first detections of Ganymede's and Callisto's optical aurorae, as well detections of new optical auroral lines at Europa, based on observations of the targets over ten Jupiter eclipses from 1998 to 2021 with Keck/HIRES. We present measurements of OI emission at 6300/6364, 5577, 7774, and 8446 A and place upper limits on hydrogen at 6563 A. These constitute the first detections of emissions at 7774 and 8446 A at a planetary body other than Earth. The simultaneous measurement of multiple emission lines provides robust constraints on atmospheric composition. We find that the eclipse atmospheres of Europa and Ganymede are composed predominantly of O2 with average column densities of (4.1 \pm 0.1) x 10^{14} cm^{-2} and (4.7 \pm 0.1) x 10^{14} cm^{-2}, respectively. We find weak evidence for H2O in Europa's bulk atmosphere at an H2O/O2 ratio of $\sim$0.25, and place only an upper limit on H2O in Ganymede's bulk atmosphere, corresponding to H2O/O2 < 0.6. The column density of O2 derived for Callisto is (4.0 \pm 0.9 x 10^{15} cm^{-2} for an assumed electron density of 0.15 cm^{-3}, but electron properties at Callisto's orbit are very poorly constrained., Comment: Published in Planetary Science Journal

Published
2023
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5. Empirically Determined Auroral Electron Events at Mars—MAVEN Observations

Author

Xu, Shaosui, primary, Mitchell, David L., additional, McFadden, James P., additional, Schneider, Nicholas M., additional, Milby, Zachariah, additional, Jain, Sonal, additional, Weber, Tristan, additional, Brain, David A., additional, DiBraccio, Gina A., additional, Halekas, Jasper, additional, Ruhunusiri, Suranga, additional, Mazelle, Christian, additional, Lillis, Robert J., additional, and Johnston, Ben, additional

Published
2022
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7. Discrete Aurora at Mars: Dependence on Upstream Solar Wind Conditions

Author

Girazian, Zachary, primary, Schneider, Nicholas M., additional, Milby, Zachariah, additional, Fang, Xiaohua, additional, Halekas, Jasper S., additional, Weber, Tristan, additional, Jain, Sonal, additional, Gerard, Jean Claude, additional, Soret, Lauriane, additional, Deighan, Justin, additional, and Lee, Christina O., additional

Published
2022
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12. Seasonal and diurnal variation in vertical profiles of the Martian nitric oxide nightglow layer

Author

Milby, Zachariah, Schneider, Nicholas, Jain, Sonal, González-Galindo, F., Royer, Emilie, Gérard, Jean-Claude, Dieghan, Justin, Stewart, Ian, Forget, François, and Lefèvre, Franck

Abstract

EPSC-DPS Joint Meeting 2019, held 15-20 September 2019 in Geneva, Switzerland, id. EPSC-DPS2019-760-1.- © Author(s) 2019. CC Attribution 4.0 license. https://creativecommons.org/licenses/by/4.0/deed.es

Published
2019

13. Loss of the Martian atmosphere to space: Present-day loss rates determined from MAVEN observations and integrated loss through time

Author

Jakosky , Bruce, Brain , David, Chaffin , Michael, Curry , Shannon M., Deighan , Justin, Grebowsky , Joseph, Halekas , Jasper, Leblanc , François, Lillis , Robert, Luhmann , Janet, Andersson , Laila, André , Nicolas, Andrews , David, Baird , Darren, Baker , Daniel, Bell , Jared, Benna , Mehdi, Bhattacharyya , Dolon, Bougher , Stephen, Bowers , Charlie, Chamberlin , Phillip, Chaufray , Jean-Yves, Clarke , John, Collinson , Glyn, Combi , Michael, Connerney , Jack, Connour , Kyle, Correira , J., Crabb , Kyle, Crary , Frank, Cravens , Thomas, Crismani , Matteo, Delory , Greg, Dewey , Ryan, DiBraccio , Gina, Dong , Chuanfei, Dong , Yaxue, Dunn , Patrick, Egan , Hilary, Elrod , Meredith K., England , Scott, Eparvier , Frank, Ergun , Robert, Eriksson , Anders, Esman , Teresa, Espley , Jared, Evans , S., Fallows , Kathryn, Fang , Xiaohua, Fillingim , Matthew, Flynn , C., Fogle , A., Fowler , Christopher M., Fox , Jane L., Fujimoto , Masaki, Garnier , Philippe, Girazian , Zachary, Groeller , Hannes, Gruesbeck , Jacob, Hamil , O., Hanley , K., Hara , Takuya, Harada , Yuki, Hermann , Jacob, Holmberg , Mika, Holsclaw , Greg, Houston , S., Inui , S., Jain , Sonal, Jolitz , Rebecca, Kotova , Anna, Kuroda , Takeshi, Larson , Davin, Lee , Yuni, Lee , C., Lefèvre , Franck, Lentz , Christy, Lo , D., Lugo , Rafael, Ma , Yingjuan, Mahaffy , Paul R., Marquette , Melissa, Matsumoto , Y., Mayyasi , Majd, Mazelle , Christian, Mcclintock , William, McFadden , Jim, Medvedev , A., Mendillo , Michael, Meziane , K., Milby , Zachariah, Mitchell , D., Modolo , Ronan, Montmessin , Franck, Nagy , Andrew, Nakagawa , H., Narvaez , Clara, Olsen , Kirk, Pawlowski , D., Peterson , William, Rahmati , Ali, Roeten , Kali, Romanelli , Norberto, Ruhunusiri , Suranga, Russell , Christopher T., Sakai , Shotaro, Schneider , Nicholas, Seki , K., Sharrar , R., Shaver , S., Siskind , David E., Slipski , Marek, Soobiah , Yasir, Steckiewicz , Morgane, Stevens , Michael, Stewart , Ian, Laboratory for Atmospheric and Space Physics [Boulder] ( LASP ), University of Colorado Boulder [Boulder], Space Sciences Laboratory [Berkeley] ( SSL ), University of California [Berkeley], NASA Goddard Space Flight Center ( GSFC ), Department of Physics and Astronomy [Iowa City], University of Iowa [Iowa], HEPPI - 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 ), Institut de recherche en astrophysique et planétologie ( IRAP ), Université Paul Sabatier - Toulouse 3 ( UPS ) -Observatoire Midi-Pyrénées ( OMP ) -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 ), Center for Space Physics [Boston] ( CSP ), Boston University [Boston] ( BU ), Department of Climate and Space Sciences and Engineering ( CLaSP ), University of Michigan [Ann Arbor], Department of Atmospheric, Oceanic, and Space Sciences [Ann Arbor] ( AOSS ), Communications and Power Industries ( CPI ), Department of Physics and Astronomy [Lawrence], University of Kansas [Lawrence] ( KU ), Princeton University, University of Arizona, Wright State University [Dayton], Institute of Space and Astronautical Science ( ISAS ), University of Kansas, Department of Physics and Astronomy [Ames, Iowa], Iowa State University ( ISU ), The University of Tokyo, National Institute of Information and Communications Technology ( NICT ), IMPEC - LATMOS, Analytical Mechanics Associates, Inc., University of California at Los Angeles [Los Angeles] ( UCLA ), Max-Planck-Institut für Sonnensystemforschung ( MPS ), Tohoku University [Sendai], Eastern Michigan University, Institute of Geophysics and Planetary Physics [Los Angeles] ( IGPP ), Department of Earth and Planetary Science [Tokyo], and Naval Research Laboratory ( NRL )

Subjects
Mars atmosphere, [ PHYS.PHYS.PHYS-AO-PH ] Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Atmosphere, Magnetospheres, Solar wind, Mars, Mars climate
Abstract

International audience; Observations of the Mars upper atmosphere made from the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft have been used to determine the loss rates of gas from the upper atmosphere to space for a complete Mars year (16 Nov 2014 – 3 Oct 2016). Loss rates for H and O are sufficient to remove ∼2-3 kg/s to space. By itself, this loss would be significant over the history of the planet. In addition, loss rates would have been greater early in history due to the enhanced solar EUV and more-active Sun. Integrated loss, based on current processes whose escape rates in the past are adjusted according to expected solar evolution, would have been as much as 0.8 bar CO2 or 23 m global equivalent layer of H2O; these losses are likely to be lower limits due to the nature of the extrapolation of loss rates to the earliest times. Combined with the lack of surface or subsurface reservoirs for CO2 that could hold remnants of an early, thick atmosphere, these results suggest that loss of gas to space has been the dominant process responsible for changing the climate of Mars from an early, warmer environment to the cold, dry one that we see today.

Published
2018

14. Mars’ seasonal mesospheric transport seen through nitric oxide nightglow

Author

Milby, Zachariah, Stiepen, Arnaud, Jain, Sonal, Schneider, Nicholas M., Deighan, Justin, Gonzalez-Galindo, Francisco, Gérard, Jean-Claude, Stevens, Michael H., Bougher, Stephen W., Evans, J. Scott, Stewart, A. Ian, Chaffin, Michael, Crismani, Matteo, Mcclintock, William E., Clarke, John T., Holsclaw, Greg, Montmessin, Franck, Lefèvre, Franck, Forget, Francois, Lo, Daniel Y., Hubert, Benoît, Jakosky, Bruce, Cardon, Catherine, Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Space Sciences, Technologies and Astrophysics Research Institute (STAR), Université de Liège, Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Naval Research Laboratory (NRL), Department of Climate and Space Sciences and Engineering (CLaSP), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Computational Physics, Inc., Center for Space Physics [Boston] (CSP), Boston University [Boston] (BU), 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), STRATO - LATMOS, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), 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), Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, 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), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
[SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics]
Abstract

International audience; We analyze the ultraviolet nightglow in the atmosphere of Mars through nitric oxide (NO) δ and γ band emissions as observed by the Imaging UltraViolet Spectrograph (IUVS) instrument onboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft when it is at apoapse and periapse.In the dayside thermosphere of Mars, solar extreme-ultraviolet radiation dissociates CO2 and N2 molecules. O(3P) and N(4S) atoms are carried from the dayside to the nightside by the day-night hemispheric transport process, where they descend through the nightside mesosphere and can radiatively recombine to form NO(C2Π). The excited molecules rapidly relax by emitting photons in the UV δ and γ bands. These emissions are indicators of the N and O atom fluxes from the dayside to Mars’ nightside and the descending circulation pattern from the nightside thermosphere to the mesosphere (e.g. Bertaux et al., 2005 ; Bougher et al., 1990 ; Cox et al., 2008 ; Gagné et al., 2013 ; Gérard et al., 2008 ; Stiepen et al., 2015, 2017).Observations of these emissions are gathered from a large dataset spanning different seasonal conditions.We present discussion on the variability in the brightness and altitude of the emission with season, geographical position (longitude), and local time, along with possible interpretation by local and global changes in the mesosphere dynamics. We show the possible impact of atmospheric waves forcing longitudinal variability and data-to-model comparisons indicating a wave-3 structure in Mars’ nightside mesosphere. Quantitative comparison with calculations of the Laboratoire de Météorologie Dynamique-Mars Global Climate Model (LMD-MGCM) suggests the model reproduces both the global trend of NO nightglow emission and its seasonal variation. However, it also indicates large discrepancies, with the emission up to a factor 50 times fainter in the model, suggesting that the predicted transport is too efficient toward the night winter pole in the thermosphere by ˜20° latitude to the north.These questions are now addressed through an extensive dataset of disk images, in complement to improved simulations of the LMD-MGCM and the Mars Global Ionosphere-Thermosphere Model (MGITM) models.

Published
2017

15. Seasonal Transport in Mars’ Mesosphere-Thermosphere revealed by Nitric Oxide nightglow

Author

Stiepen, Arnaud, Royer, Emilie M., McCord Schneider, Nicholas, Jain, Sonal, Milby, Zachariah, Deighan, Justin, Gonzalez-Galindo, Francisco, Bougher, Stephen W., Gérard, Jean-Claude, Stevens, Michael H., Evans, J. Scott, Stewart, Ian F., Chaffin, Michael, Mcclintock, Bill, Clarke, John T., Montmessin, Franck, Holsclaw, Greg, Lefèvre, Franck, Forget, François, Lo, Daniel, Hubert, Benoit A., Jakosky, Bruce Martin, Cardon, Catherine, Laboratoire de Physique Atmosphérique et Planétaire (LPAP), Université de Liège, Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Department of Climate and Space Sciences and Engineering (CLaSP), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Naval Research Laboratory (NRL), Computational Physics, Inc., Center for Space Physics [Boston] (CSP), Boston University [Boston] (BU), 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), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), 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), University of Arizona, 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), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
[SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics]
Abstract

International audience; We analyze the ultraviolet nightglow in the atmosphere of Mars through the Nitric Oxide (NO) δ and γ band emissions observed by the Imaging Ultraviolet Spectrograph (IUVS, McClintock et al., 2015) when the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft is at apoapsis and periapsis.On the dayside thermosphere of Mars, solar extreme ultraviolet radiation dissociates CO2 and N2 molecules. O(3P) and N(4S) atoms are carried by the day-to-night hemispheric transport. They descend in the nightside mesosphere, where they can radiatively recombine to form NO(C2Π). The excited molecules rapidly relax by emitting UV photons in the δ and γ bands. These emissions are thus indicators of the N and O atom fluxes transported from the dayside to Mars’ nightside and the descending circulation pattern from the nightside thermosphere to the mesosphere (e.g. Bertaux et al., 2005 ; Bougher et al., 1990 ; Cox et al., 2008 ; Gagné et al., 2013 ; Gérard et al., 2008 ; Stiepen et al., 2015, 2017).A large dataset of nightside disk images and vertical limb scans during southern winter, fall equinox and southern summer conditions have been accumulated since the beginning of the mission.We will present a discussion regarding the variability of the brightness and altitude of the emission with season, geographical position (longitude) and local time and possible interpretation for local and global changes in the mesosphere dynamics. We show the possible impact of atmospheric waves structuring the emission longitudinally and indicating a wave-3 structure in Mars’ nightside mesosphere. Quantitative comparison with calculations from the LMD-MGCM (Laboratoire de Météorologie Dynamique-Mars Global Climate Model) show that the model globally reproduces the trends of the NO nightglow emission and its seasonal variation but also indicates large discrepancies (up to a factor 50 fainter in the model) suggesting that the predicted transport is too efficient toward the night winter pole in the thermosphere by ∼20° latitude north.These questions are now addressed with an extensive dataset of disk images, complemented with improved simulations from the LMD-MGCM and new M-GITM (Mars Global Ionosphere-Thermosphere Model) simulations of emissions for selected sampling periods.

Published
2017

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