Issue |
A&A
Volume 386, Number 1, April IV 2002
|
|
---|---|---|
Page(s) | 319 - 330 | |
Section | Celestial mechanics and astrometry | |
DOI | https://doi.org/10.1051/0004-6361:20020097 | |
Published online | 15 April 2002 |
Discovery of X–rays from Venus with Chandra
1
Max–Planck–Institut für extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany
2
University of Maryland, Department of Astronomy, College Park, MD 20742, USA
3
Chandra X–Ray Center, Harvard–Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
Corresponding author: K. Dennerl, kod@mpe.mpg.de
Received:
28
September
2001
Accepted:
17
January
2002
On January 10 and 13, 2001, Venus was observed for the first time
with an X–ray astronomy satellite. The observation, performed with the
ACIS–I and LETG/ACIS–S instruments on Chandra, yielded data of
high spatial, spectral, and temporal resolution. Venus is clearly
detected as a half–lit crescent, with considerable brightening on the
sunward limb. The morphology agrees well with that expected from
fluorescent scattering of solar in the planetary atmosphere.
The radiation is observed at discrete energies, mainly at the
energy of 0.53 keV. Fluorescent radiation is also
detected from C–Kα at 0.28 keV and, marginally, from
N–Kα at 0.40 keV. An additional emission line is indicated
at 0.29 keV, which might be the signature of the
C transition in CO2 and CO.
Evidence for temporal variability of the
X–ray flux was found at the
level, with fluctuations by
factors of a few times indicated on time scales of minutes. All these
findings are fully consistent with fluorescent scattering of solar
X–rays. No other source of X–ray emission was detected, in
particular none from charge exchange interactions between highly
charged heavy solar wind ions and atmospheric neutrals, the dominant
process for the X–ray emission of comets. This is in agreement with
the sensitivity of the observation.
Key words: atomic processes / molecular processes / scattering / Sun: X–rays, gamma rays / planets and satellites: individual: Venus / X–rays: general
© ESO, 2002
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.