x-rays from mars k. dennerl, c. lisse, a. bhardwaj, v. burwitz, j. englhauser, h. gunell, m....
TRANSCRIPT
X-rays from Mars
K. Dennerl, C. Lisse, A. Bhardwaj, V. Burwitz, J. Englhauser, H. Gunell, M.
Holstrom, F. Jansen, V. Kharchenko, and P. Rodriguez-Pascual
Chandra
XMM
Halo
(CXE)
Disk
(scattering)
There Are Many Sources of X-rays in the Solar System (Planets, Moons, Io Flux
Torus, Comets, Sun); But the 0.3-1.5 keV Emission Mechanisms Are Still Uncertain.
VenusMars
SaturnJupiter Comets
Auroral
Scattering
Charge
Exchange
Excellent new review of the current understanding of s.s. xrays : Bhardwaj et al., PSS 55, 1135 (2007)
January 2001: first X-ray image of Venus (Chandra ACIS-I)
First X-ray observation of Venus during solar maximum: Scattering of solar X-rays detected, but no conclusive evidence of charge exchange. => To understand the charge exchange component, the solar wind flux and charge state will have to be very well known. The first two-spacecraft measure of the solar wind at another planet, by MESSENGER and Venus Express during the V2 flyby, will provide this data.
Dennerl et al. 2002, A&A 386, 319
Solar X-rays
Venus ACIS-I
Planning the Mars observation
2001 July 4
Catching Mars with Chandra
Optical depth of the Martian atmosphere
Simulated X-ray images of Mars
due to fluorescent scattering of solar X-rays
C-Kα
Lx ~ 2.9 MW
N-Kα
Lx ~ 0.1 MW
O-Kα
Lx ~ 1.7 MW
Chandra observation
Spatial distribution of X-ray photons around Mars
Spectral distribution of X-ray photons around Mars
background
Chandra observation
Gunell et al. 2004, Geophysical Research Letters 31
Trajectories for O6+ ions around Mars
90°60°
30°0°
Parallel projection of X-ray emission on 4 July 2001
X-ray imaging of the solar wind – Mars interaction
Holmström, Barabash, Kallio, Geophysical Research Letters 28, 1287-1290, 2001
Parallel projections of X-ray emission at solar minimum
18.2°
Chandra observationCharge exchange simulation
Gunell et al. 2004, Geoph. Res. Letters 31
Spatial distribution of X-ray photons around Mars
Mars observed with XMM-Newton2003 Nov 20, 00:08 – Nov 21, 04:57 UTC
XMM-Newton
Mars observed with XMM-Newton2003 Nov 20, 00:08 – Nov 21, 04:57 UTC
XMM-Newton observation of Mars
EPIC pn
sky coordinates
X-ray image
exposure map
pixel size: 1“ pixel size: 5“
XMM-Newton images of Mars
Solar X-ray flux (1.55 - 12.4 keV)
+ 10“
- 10“
“disk”
High resolution X-ray spectroscopy of Mars with RGS
dispersion direction
G(O+6) = (f+i)/r = 0.8 +/- 0.6, i=0
Lx = 3.4 +/- 0.4 MW
C
5+
N 6+O
6+
CO2
O 7+
Ne
7+?C
4+
N2
“halo”
+ 15“
+ 50“
- 15“
- 50“
High resolution X-ray spectroscopy of Mars with RGS
C
5+
N 6+O
6+
CO2
O 7+
Ne
7+?C
4+
G(O+6) = (f+i)/r = 5 - 6, i =0
Lx = 12.8 +/- 1.4 MW
O+8/ O+7 = 0.34 +/- 0.10
High resolution X-ray spectroscopy of Mars with RGS
halo
disk
C 5+
N 6+
O 6+
CO2
O 7+
Ne 7+
?
C 4+
High resolution X-ray spectroscopy of Mars
X-ray line emission from Mars
solar wind ions
charge exchange
12.8 ± 1.4 MW
Mars atmosphere
fluorescence
3.4 ± 0.4 MW
High resolution X-ray spectroscopy of Mars with RGS
High resolution X-ray spectroscopy of Mars
X-ray images of Mars in individual emission lines (!)
O7+: 2p → 1s O6+: 2 3S1 → 1 1S0
X-ray images of Mars in individual emission lines (!)
X-ray images of Mars in individual emission lines (!)
C5+: 3p → 1s C5+: 2p → 1s
X-ray images of Mars in individual emission lines (!)
X-ray images of Mars in individual emission lines (!)
N2: 2p → 1sCO2: 4σg→ 1s, 3σu→ 1s, 1πu →
1s
CO2: 1πg→ 1s
X-ray images of Mars in individual emission lines (!)
X-ray images of Mars in individual emission lines (!)
Emission centered
on disk.
Emission in crescent
offset towards the Sun.
Emission above and below
Poles (!?) or in limb-effect
crescent.
X-ray color image of Mars
Fin.
Questions :Is Ne72 line really Ne82 line? Ne+7 is lithium like, should have a low energy transition, not one at 800 - 900 eV. The Ne+8 lines are at 905, 916, and 922 eV. (Ali)
How is RGS data binned? Non-linear, so is 872 eV really 872, or maybe 905 - 920 eV or 830? (Wargelin)
What is the composition of the Martian exosphere in the Holstrom et al. model? All H? No C, O, CO2? Viking may be the only s/c to measure exosphere composition. Was Mars in Northern summer in 2003, explaing brighter emission of O on the North? (Cravens, Kharchenko)
What does the spatial extent of the CO2 tell you? Is the apparent CO2 in the halo due to the coarse XMM imaging (PSF wings), or due to CO2 in the exosphere? Is the halo emission overlapped by emission from the extended Martian disk? (Kharchenko)
How good are the SNR of the different lines in the disk and halo fits? 2 pts not fit at 385 eV seem as significant as fit lines at other wavelengths (Beiersdorfer)
What is the spectral profile of the O+6 f,I,r lines? (Kharchenko)
O+8/O+7 ratios varies a LOT in the SW. SW O+8/O+7 ratio varies by up to 2 orders of magnitude. We have to be careful when comparing to an “average”. Also, how can the O+7/O+6 ratio be 0.34, yet the solar wind flux and activity be 10x higher than during the CXO observations in 2001? I.e., cold stable wind ratios with very high density? (Edgar)