What we can Learn
Konrad Dennerl
Max-Planck-Institut für extraterrestrische Physik
Garching bei München, Germany
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
X-rays from comets and non-magnetic planets are powered by the Sun
There are two different processes at work:
solar X-rays
solar wind
SOHO LASCO C2, 20.3.- 10.4.1999, visible light
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
no global magnetic field
presence of an atmosphere
similar distance from Sun as
active comets
exposed to high solar photon
and solar wind flux
nearby objects
Venus
Konrad Dennerl
Mars
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Size comparison
Venus
Konrad Dennerl
Earth
X-rays from Planetary Exospheres
Mars
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Mass comparison
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Mass comparison
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Mass comparison
MMars = 0.64 x 1024 kg
MVenus = 4.87 x 1024 kg
= 7.6 x MMars
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Venus atmosphere: 4.8 x 1020 kg
Earth atmosphere: 5.1 x 1018 kg
Mars atmosphere: 2.5 x 1016 kg
total mass of a comet: ~1014 kg
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Solar wind charge exchange

Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Scattering of solar X-rays

Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Scattering of solar X-rays

Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Solar wind charge exchange

Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Two possible mechanisms
for X-rays from
atmospheres of nonmagnetic planets
Charge Exchange with
Solar Wind Ions
Scattering of
Solar X-rays
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
XMM/RGS spectra of Comet C/2000 WM1 and of Mars
No X-ray fluorescence from cometary coma
Charge Exchange
Fluorescence
(too tenuous, cross sections too low)
Comet
Charge Exchange
O6+
r i f
Fluorescence
Mars
23.50 A 23.68 A
O6+
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Chandra
XMM-Newton
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Geometry of the first Mars observation
2001 July 4
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Density of the Martian atmosphere
Konrad Dennerl
X-rays from Planetary Exospheres
(Sehnal 1990)
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Photoabsorption cross sections
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Optical depth of the Martian atmosphere
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Modeling the X-ray appearance of Mars
due to fluorescent scattering of solar X-rays
Sun
Mars
atmosphere
(not drawn to scale)
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Modeling the X-ray appearance of Mars
due to fluorescent scattering of solar X-rays
Sun
Mars
atmosphere
(not drawn to scale)
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Solar X-ray spectrum
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Fluorescent scattering of solar X-rays: volume emissivity
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Modeling the X-ray appearance of Mars
due to fluorescent scattering of solar X-rays
Sun
Mars
atmosphere
(not drawn to scale)
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Simulated X-ray images of Mars
due to fluorescent scattering of solar X-rays
Konrad Dennerl
C-Kα
N-Kα
O-Kα
Lx ~ 2.9 MW
Lx ~ 0.1 MW
Lx ~ 1.7 MW
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Spatial distribution of X-ray photons around Mars
Chandra observation
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Spatial distribution of X-ray photons around Mars
Chandra observation
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Spatial distribution of X-ray photons around Mars
Charge exchange simulation
Gunell etChandra
al. 2004,observation
Geoph. Res. Letters 31
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Spectral distribution of X-ray photons around Mars
background
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
First XMM-Newton observation of Mars
2003 Nov 20, 00:08 – Nov 21, 04:57 UTC
XMM-Newton
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Solar X-ray flux (1.55 - 12.4 keV)
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Geometry of the first XMM-Newton Mars observation
Earth
Mars
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Aurora above Garching/Munich, 20 November 2003
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Aurora above Garching/Munich, 20 November 2003
Summer Triangle
Pegasus
Mars
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
XMM-Newton images of Mars
pixel size: 1“
Konrad Dennerl
X-rays from Planetary Exospheres
pixel size: 5“
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Spatial distribution of X-ray photons
Mars
Mars
PSF
1´
Star (ζ Pup)
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
X-ray lightcurves of the Sun and of Mars
Sun
Mars
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
The Sun on 27 October 2003
optical light
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
The Sun on 18 November 2003
18. November 2003
optical light
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Coronal Mass Ejection (CME) on 18 November 2003
from sunspot 484, reached the Earth magnetosphere on 20 November 2003 . .
Konrad Dennerl
Boston, 2010
2011 Mar
May 15
23
X-rays from Planetary Exospheres
Charge Transfer ReactionsAAS 218, 12-Years Chandra,Utrecht,
Sun
Earth
Mars
XMM-Newton Mars observation
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Sun
Earth
Mars
XMM-Newton Mars observation
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Sun
Earth
Mars
XMM-Newton Mars observation
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Sun
Earth
Mars
X-ray flares of the Martian
exosphere
XMM-Newton Mars observation
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
3D kinematic solar wind model (Hakamada-Akasofu-Fry version 2/HAFv.2)
Dryer, Deehr, Fry, Smith, McKenna-Lawlor et al., 2007, priv. comm.
solar wind
particle flux
[ 108 cm-2 s-1 ]
Sun
Earth
Mars
November 2003
17
Konrad Dennerl
18
X-ray flares of the Martian
exosphere
XMM-Newton
XMM-NewtonMars
Marsobservation
observation
19
20
21
X-rays from Planetary Exospheres
22
23
24
25
AAS 218, 12-Years Chandra, Boston, 2011 May 23
High resolution X-ray spectroscopy of Mars with XMM-Newton / RGS
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
High resolution X-ray spectroscopy of Mars with XMM-Newton / RGS
+ 50“
all
- 50“
dispersion direction
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
High resolution X-ray spectroscopy of Mars with XMM-Newton / RGS
+ 10“
“disk”
- 10“
dispersion direction
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
High resolution X-ray spectroscopy of Mars with XMM-Newton / RGS
Ne9+
?
O 7+
O 6+
N 6+
CO2
C 5+
C 4+
+ 50“
“halo”
+ 15“
- 15“
- 50“
dispersion direction
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
X-ray line emission from Mars
solar wind ions
solar X-rays
charge
exchange
fluorescence
12.8 ± 1.4 MW
3.4 ± 0.4 MW
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
High resolution X-ray spectroscopy of Mars with RGS
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
High resolution X-ray spectroscopy of Mars
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Charge exchange at Mars
Singlet State
Triplet State
1s 2p P1
1
1s 2s
2
1
0
1S
0
O6+
r i
f
r i
f
1s 2p 3 P0,1,2
r
i
21.60 Ǻ
1s 2s 3S1
21.81 Ǻ
574.0 eV
568.5 eV
(2 photon
continuum)
f
22.11 Ǻ
560.9 eV
1s2 1S0
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
High resolution X-ray spectroscopy of Mars with RGS
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
First X-ray colour image of Mars
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Simulated exospheric densities for..
equinox
solar minimum
solar minimum
aphelion
solar maximum
equinox
2.7 Gyr ago
perihelion
3.6 Gyr ago
Valeille et al. 2009
Konrad Dennerl
solar minimum & equinox
X-rays from Planetary Exospheres
presence
AAS 218, 12-Years Chandra, Boston, 2011 May 23
From solar maximum to solar minimum ..
1995
Yohkoh SXT
1991
Konrad Dennerl
X-rays from Planetary Exospheres
0.25 – 4.0 keV
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Ulysses: Solar wind properties near ..
solar minimum
solar maximum
McComas et al., GRL, 30, 24, 2003
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
solar minimum
Konrad Dennerl
X-rays from Planetary Exospheres
solar maximum
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Second XMM-Newton observation of Mars
2009 Nov 22 – 25 (140 ks!)
XMM-Newton
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Second XMM-Newton observation of Mars
2009 Nov 22 – 25 (140 ks)
Sun, 2009 Nov 20
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Second XMM-Newton observation of Mars
2009 Nov 22 – 25 (140 ks!)
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Second XMM-Newton observation of Mars
2009 Nov 22 – 25 (140 ks!)
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Venus
Chandra
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
X-ray observations of Venus
Challenge #1: separating Fluorescence and Charge Exchange
Simulated X-ray images of Venus for ..
Konrad Dennerl
.. scattering of solar X-rays
.. solar wind charge exchange
(logarithmic intensity scale)
(logarithmic intensity scale)
Dennerl et al. 2002, A&A 386
Gunell et al. 2007, GRL 34
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Density of the Venus atmosphere
(Seiff 1983)
Density of the Mars atmosphere
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Optical/collisional depth of the Venus atmosphere
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
X-ray observations of Venus
Challenge #2: Optical Flux
apparent visual surface brightness [ mag/arcsec2 ]:
• Mercury: 0.9 .. ~5.6
• Venus: -0.7 .. +1.5
• Mars:
3.8 .. 4.7
• Jupiter:
5.1 .. 5.5
• Saturn:
6.8 .. 7.2
• Uranus:
8.2 .. 8.3
• Neptune:
9.4
0
Konrad Dennerl
X-rays from Planetary Exospheres
5
10
AAS 218, 12-Years Chandra, Boston, 2011 May 23
X-ray observations of Venus
Challenge #3: Solar Elongation
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
The inner solar system on 2007-Jun-06
Chandra
Venus
Earth
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
The inner solar system on 2007-Jun-06
x
Chandra
Venus
Angle Sun-Earth-Venus:
45.41 deg
Earth
Minimum angle for
Chandra:
45.54 deg
(hard limit)
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Geometry of the first X-ray observation of Venus
2001 January 13
X-ray
opticalimage
image
V ~ -4.4 mag
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Comparison of the Venus morphology
X-ray (Chandra)
Konrad Dennerl
X-rays from Planetary Exospheres
optical (4“ Newton)
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Simulated X-ray images of Venus for fluorescent scattering
simulation
Konrad Dennerl
simulation
simulation
C-Kα
N-Kα
O-Kα
Lx ~ 16 MW
Lx ~ 1 MW
Lx ~ 40 MW
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
X-ray images of Venus: simulation  observation
simulation
C-Kα
Lx ~ 16 MW
Konrad Dennerl
observation
observed image
(smoothed)
X-rays from Planetary Exospheres
simulation
O-Kα
Lx ~ 40 MW
AAS 218, 12-Years Chandra, Boston, 2011 May 23
X-ray grating spectrum of Venus (Chandra LETG/ACIS-S)
C-Kα
N-Kα ?
O-Kα
O-Kα
CO,CO2: 1s → π* ?
Dennerl et al. 2002
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Spatial distribution of X-ray photons around Venus
Chandra observation
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Spatial distribution of X-ray photons around Mars
Chandra observation
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Simulated X-ray images of Venus for ..
Konrad Dennerl
.. scattering of solar X-rays
.. solar wind charge exchange
(logarithmic intensity scale)
(logarithmic intensity scale)
Dennerl et al. 2002, A&A 386
Gunell et al. 2007, GRL 34
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Simulated X-ray images of Venus for ..
Konrad Dennerl
.. scattering of solar X-rays
.. solar wind charge exchange
(logarithmic intensity scale)
(logarithmic intensity scale)
Dennerl et al. 2002, A&A 386
Gunell et al. 2007, GRL 34
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Simulated X-ray images of Venus for ..
Konrad Dennerl
.. scattering of solar X-rays
.. solar wind charge exchange
(logarithmic intensity scale)
(logarithmic intensity scale)
Dennerl et al. 2002, A&A 386
Gunell et al. 2007, GRL 34
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Yohkoh SXT
0.25 – 4.0 keV
1995
1991
Chandra ACIS-I
1987
2008
0.2 – 1.0 keV
GOES-7, 8, 10, 12
1.6 – 12.4 keV
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
X-ray images of Venus, 2001 & 2006 (Chandra ACIS-I)
2001 January 13
Konrad Dennerl
12 ks
X-rays from Planetary Exospheres
2006 March 27
77 ks
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Second Chandra observation of Venus, 2006 March 27 (ACIS-I, 74.9 ks)
charge exchange
400* eV
fluorescence
615* eV
660* eV
charge exchange
900* eV
* energies shifted by ~110 eV due to optical loading
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Second Chandra observation of Venus, 2006 March 27 (ACIS-I, 74.9 ks)
charge exchange
400* eV
fluorescence
615* eV
660* eV
charge exchange
900* eV
* energies shifted by ~110 eV due to optical loading
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Second Chandra observation of Venus, 2006 March 27 (ACIS-I, 74.9 ks)
charge exchange
400* eV
fluorescence
615* eV
660* eV
charge exchange
900* eV
* energies shifted by ~110 eV due to optical loading
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Second Chandra observation of Venus, 2006 March 27 (ACIS-I, 74.9 ks)
charge exchange
400* eV
fluorescence
615* eV
660* eV
charge exchange
900* eV
* energies shifted by ~110 eV due to optical loading
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Second Chandra observation of Venus, 2006 March 27 (ACIS-I, 74.9 ks)
charge exchange
400* eV
fluorescence
615* eV
660* eV
charge exchange
900* eV
* energies shifted by ~110 eV due to optical loading
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Second Chandra observation of Venus, 2006 March 27 (ACIS-I, 74.9 ks)
charge exchange
400* eV
fluorescence
615* eV
660* eV
charge exchange
900* eV
* energies shifted by ~110 eV due to optical loading
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Second Chandra observation of Venus, 2006 March 27 (ACIS-I, 74.9 ks)
charge exchange
400* eV
fluorescence
615* eV
660* eV
charge exchange
900* eV
* energies shifted by ~110 eV due to optical loading
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Second Chandra observation of Venus, 2006 March 27 (ACIS-I, 74.9 ks)
counts
O-Kα fluorescence
charge exchange
400* eV
fluorescence
615* eV
660* eV
‘disk’
charge exchange
900* eV
* energies shifted by ~110 eV due to optical loading
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Second Chandra observation of Venus, 2006 March 27 (ACIS-I, 74.9 ks)
First evidence for exospheric X-ray emission from Venus !
O6+ charge exchange
N6+ charge exchange
‘limb’
‘disk’
charge exchange
400* eV
fluorescence
615* eV
660* eV
charge exchange
900* eV
* energies shifted by ~110 eV due to optical loading
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Second Chandra observation of Venus, 2006 March 27 (ACIS-I, 74.9 ks)
‘limb’
‘disk’
charge exchange
400* eV
fluorescence
615* eV
660* eV
charge exchange
900* eV
* energies shifted by ~110 eV due to optical loading
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Yohkoh SXT
0.25 – 4.0 keV
1995
1991
Chandra ACIS-I
0.4 – 0.9 keV
GOES-7, 8, 10, 12
1.6 – 12.4 keV
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
X-ray images of Venus, 2001-2007 (Chandra ACIS-I)
2001 January 13 12 ks
Konrad Dennerl
2006 March 27 77 ks
X-rays from Planetary Exospheres
2007 October 30 82 ks
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Comparison of the Venus X-ray observations of 2006 and 2007
March 2006
Oct 2007
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
2. O VII emission at 565 eV
3. O VIII emission at 654 eV
low abundance of highly charged oxygen  cold wind
high abundance of highly charged oxygen  hot wind
Chandra ACIS-I spectrum of Venus:
E
E
F
F
G
G
C
C
A
A
B
B
D
D
C+N ~ O VII
1. C and N emission below 500 eV
H
H
O VIII / O VII flux increases
three competing emission features:
C+N ~ O VII
Chandra ACIS-S spectra of comets:
Bodewits et al., A&A 469, 2007
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
X-ray observations have opened up a completely new possibility of remote global
imaging of planetary exospheres and their response to solar activity.
At Venus and Mars, the absence of a global magnetic field enables a straightforward
study of how a planetary exosphere responds to the incident solar photon and ion flux.
Scattering of solar X-rays is most efficient at atmospheric heights of 100-140 km,
providing direct observational access to regions which are difficult to study otherwise.
Charge exchange induced X-rays are a most sensitive tracer of planetary outgassing,
thus linking X-ray astrophysics to astrobiology.
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23
Konrad Dennerl
X-rays from Planetary Exospheres
AAS 218, 12-Years Chandra, Boston, 2011 May 23