X-Rays From Mars

X-rays from Mars were first detected in July 2001 with the satellite Chandra. The main source of this radiation was fluorescent scattering of solar X-rays in its upper atmosphere. In addition, the presence of an extended X-ray halo was indicated, probably resulting from charge exchange interactions between highly charged heavy ions in the solar wind and neutrals in the Martian exosphere. The statistical significance of the X-ray halo, however, was very low. In November 2003, Mars was observed again in X-rays, this time with the satellite XMM-Newton. This observation, characterized by a considerably higher sensitivity, confirmed the presence of the X-ray halo and proved that charge exchange is indeed the origin of the emission. This was the first definite detection of charge exchange induced X-ray emission from the exosphere of another planet. Previously, this kind of emission had been detected from comets (which are largely exospheres) and from the terrestrial exosphere. Because charge exchange interactions between atmospheric constituents and solar wind ions are considered as an important nonthermal escape mechanism, probably responsible for a significant loss of the Martian atmosphere, X-ray observations may lead to a better understanding of the present state of the Martian atmosphere and its evolution. X-ray images of the Martian exosphere in specific emission lines exhibited a highly anisotropic morphology, varying with individual ions and ionization states. With its capability to trace the X-ray emission out to at least 8 Mars radii, XMM-Newton can explore exospheric regions far beyond those that have been observationally explored to date. Thus, X-ray observations provide a novel method for studying processes in the Martian exosphere on a global scale.

[1]  M. Holmström,et al.  The solar wind interaction with Venus and Mars: energetic neutral atom and X-ray imaging , 2004 .

[2]  M. Krause,et al.  Atomic radiative and radiationless yields for K and L shells , 1979 .

[3]  P. Withers.  Mars Global Surveyor and Mars Odyssey Accelerometer observations of the Martian upper atmosphere during aerobraking , 2006 .

[4]  A. Vourlidas,et al.  Coronal mass ejections and other extreme characteristics of the 2003 October–November solar eruptions , 2005 .

[5]  A. Nier,et al.  Composition and structure of Mars' Upper atmosphere: Results from the neutral mass spectrometers on Viking 1 and 2 , 1977 .

[6]  Thomas E. Cravens,et al.  Comet Hyakutake x‐ray source: Charge transfer of solar wind heavy ions , 1997 .

[7]  J. Trümper.  The ROSAT Mission , 1982 .

[8]  B. Huebert,et al.  Intercomparisons of airborne measurements of aerosol ionic chemical composition during TRACE‐P and ACE‐Asia , 2004 .

[9]  J. D. Sullivan,et al.  The detection of X rays from Jupiter , 1983 .

[10]  Gary J. Rottman,et al.  The SOLAR2000 empirical solar irradiance model and forecast tool , 2000 .

[11]  V. Krasnopolsky,et al.  Soft X-Rays From Four Comets Observed With EUVE , 1997 .

[12]  V. Krasnopolsky,et al.  Charge Abundances of the Solar Wind Ions Inferred from Cometary X-Ray Spectra , 2003 .

[13]  Elmar Pfeffermann,et al.  The European Photon Imaging Camera on XMM-Newton: The pn-CCD camera , 2001 .

[14]  R. Hoffman,et al.  X-Rays from Visible Aurorae at Minneapolis , 1958 .

[15]  K. Dennerl.  Discovery of X-rays from Mars with Chandra , 2002, astro-ph/0211215.

[16]  T. Cravens,et al.  X‐ray emission from scattering and fluorescence of solar X‐rays at Venus and Mars , 2001 .

[17]  D. Liedahl,et al.  Collisional Plasma Models with APEC/APED: Emission-Line Diagnostics of Hydrogen-like and Helium-like Ions , 2001, astro-ph/0106478.

[18]  Thomas E. Cravens,et al.  X-ray emission from comets and planets , 2000 .

[19]  et al,et al.  The European Photon Imaging Camera on XMM-Newton: The MOS cameras : The MOS cameras , 2000, astro-ph/0011498.

[20]  Konrad Dennerl,et al.  X-ray Emissions from Comets Detected in the Röntgen X-ray Satellite All-Sky Survey , 1997 .

[21]  M. J. Mumma,et al.  Discovery of X-ray and Extreme Ultraviolet Emission from Comet C/Hyakutake 1996 B2 , 1996, Science.

[22]  R. J. Grader,et al.  X‐ray airglow in the daytime sky , 1968 .

[23]  Chandra Observation of an X-Ray Flare at Saturn: Evidence of Direct Solar Control on Saturn’s Disk X-Ray Emissions , 2005, astro-ph/0504110.

[24]  Mats Holmström,et al.  X‐ray imaging of the solar wind—Mars interaction , 2001 .

[25]  V. Grechnev,et al.  Large-scale activity in solar eruptive events of October–November 2003 observed from SOHO/EIT data , 2005 .

[26]  S. Manson,et al.  Photoabsorption cross sections for positive atomic ions with Z equal to or less than 30 , 1979 .

[27]  P. Gondoin,et al.  XMM-Newton observatory. I. The spacecraft and operations , 2001 .

[28]  Pekka Janhunen,et al.  Simulations of X-rays from solar wind charge exchange at Mars: Parameter dependence , 2005 .

[29]  K. Dennerl,et al.  Discovery of X-rays from Venus with Chandra , 2002, astro-ph/0204263.

[30]  V. Krasnopolsky.  On the Deuterium Abundance on Mars and Some Related Problems , 2000 .

[31]  Elmar Pfeffermann,et al.  The Focal Plane Instrumentation Of The ROSAT Telescope , 1986, Other Conferences.

[32]  R. Elsner,et al.  Solar control on Jupiter's equatorial X‐ray emissions: 26–29 November 2003 XMM‐Newton observation , 2005, astro-ph/0504670.

[33]  V. Krasnopolsky,et al.  Helium on Mars and Venus : EUVE observations and modeling , 2005 .

[34]  C. G. Justus,et al.  Global MGS TES data and Mars-GRAM validation , 2005 .

[35]  Evidence for Dust-related X-Ray Emission from Comet C/1995 O1 (Hale-Bopp) , 1997, astro-ph/9710363.

[36]  Konrad Dennerl,et al.  First observation of Mars with XMM-Newton: high resolution X-ray spectroscopy with RGS , 2006 .

[37]  Pekka Janhunen,et al.  X rays from solar wind charge exchange at Mars: A comparison of simulations and observations , 2004 .

[38]  J. Herder,et al.  The Reflection Grating Spectrometer on-board XMM-Newton: Status of the Calibrations , 2002 .

[39]  A. Dalgarno,et al.  Spectra of the X-Ray Emission Induced in the Interaction between the Solar Wind and the Heliospheric Gas , 2004 .