charge exchange in comets off the beaten track
DESCRIPTION
AAS/HEAD 2013. Charge Exchange in Comets off the beaten track. Dennis Bodewits 1 , Damian Christian 2, Casey Lisse 3 , Scott Wolk 4 , Konrad Dennerl 5 , Jenny Carter 6 , Andy Read 6 , and Susan Lepri 7. - PowerPoint PPT PresentationTRANSCRIPT
Dennis Bodewits1,
Damian Christian2, Casey Lisse3, Scott Wolk4, Konrad Dennerl5, Jenny Carter6, Andy Read6,
and Susan Lepri7
(1) Univ. Maryland, College Park, (2) CSU Northridge, (3) JHU/APL, (4) CfA, (5) MPE Garching, Germany, (6) Univ. Leicester, UK, (7) Univ. Michigan
Charge Exchange in Cometsoff the beaten track
AAS/HEAD 2013
Outline
• Charge Exchange occurs where a hot plasma meets a neutral gas.
• How can we use other wavelength regimes?• How can we use comets to study CX emission
in different plasma environments?• What will we learn with the next generation X-
ray telescopes?
A High Energy View of Comets
X-rayOptical
Dust (Continuum)
MoleculesNH2, C3, C2, NH, OH, CS, H2
Molecular ionsCO+, H2O+, CO2+, ..
Energy Wavelength
AtomsS, C, O, H
UV FUV EUV
IonsHe+, He2+, O6+, ..
Heavy IonsC5,6+, O7,8+, ..
Comet
Solar Wind
Simultaneous X-ray/UV image of a comet
APOD Feb 21, 2009, Bodewits et al. 2010, Carter et al. 2011
1. Other X-rays
Chandra Comet SurveyC,N OVII OVIII
A
B
C
D
E
G
F
H
X-ray spectra sample solar wind statelow abundance of highly charged oxygen cold windhigh abundance of highly charged oxygen hot wind
Bodewits et al. 2007
Sola
r win
d fr
eeze
-in Te
mpe
ratu
re
Temperature vs. Freeze-in Temperature
Bodewits et al. 2012
Bodewits et al. 2007
Where is the Polar wind?
OVII and OVIIINe X
Ne IX Mg XI
Mg XIISi XIII
Bodewits et al. 2007; Ewing et al. 2013.
Fe XV - XX
Comet emission > 1000 eVC/2002 C1 (Ikeya-Zhang) + CME
Si
Mg
SWCX or artifact?
Mg XI, XII?
Si XIII, XIV?
• 73P/Schwassmann-Wachmann 3b• 0.1 AU in 2006• Warm slow wind
ACE Chandra
C6+/O7+ 2.1 ± 0.7 2.1 ± 1.0
C5+/O7+ 7.6 ± 3 87 ± 29
• Cross section?• Calibration around 300 eV?• CX emission from Mg, Si, Ne…
• 90% of emission at 300 eV is NOT CV
SWCX <300 eV: terra incognita
SWCX <300 eV: terra incognita
Sasseen et al. 2006
CHIPS+Chandra observations of Comet C/2001 Q4 (NEAT)
Koutroumpa et al. 2008
SWCX Model
Si
Mg
Si and Mg as temperature probes
2. The UltraViolet: Helium Rules!
OVI: elusive SWCX emission• N(O6+) = ~10 – 20 x N(O7+)• OVI doublet around 103 nm• Doppler-shift measure SW velocity• Emission cross section comparable to
OVII features (Bodewits & Hoekstra 2007). Increase 2-3x with velocity.
• Fuse: non-detections in 3 comets (Weaver et al. 2002; Feldman et al. 2005).
• 400x smaller FOV than CXO• Best target: high inclination comet in
polar wind• Rosetta ALICE
103.1, 103.7 nm
Most abundant ions in SW emit in EUV: O6+ + H2O O5+(nl)
Bodewits & Hoekstra 2007
fast
slow
OVI Line Ratio 11.6 / 17.0 nm
• 1 – 10% of SW• N(He) ~ 75 xN(O)• Cross sections 1/10th
• Fully ionized
• Giotto (Fuselier ‘91)
• EUVE– He I 58.4 nm Hale-Bopp
(Krasnopolsky et al. ‘97)– He II 30.4 nm Hyakutake (Krasnopolsky
et al. ‘01)
– Venus, Mars (Krasnopolsky & Gladstone ’05)
He2+
He+
He
30.4 nm
58.4 nm
He: The Coolest Ion of Them All
He II/He I Line RatioHe He+
Electron capture strongly depends on collision partner and velocity
Bodewits et al (2004, 2006)
3. The Next Generation
Existing Observations:XMM & Suzaku Archives
SUZAKU - 73P
Brown et al. 2010 Dennerl et al. In prep.
XMM RGS – C/2000 WM1
Prospects of High Resolution Spectroscopy
•High resolution X-ray spectroscopy will reveal: features of minor species (Fe, Mg, Si)
•will allow direct measurements of the triplet/singlet ratios of CV and OVII
•may detect fluorescence features of molecules such as CO2 (Dennerl et al. 2006)
•may find continuum emission (5% of total – Krasnopolsky et al. 1997)
•Should have capabilities below 300 eV•Imaging would be awesome! (not discussed here)
Wide Field Imager at GSFC?
C/2012 S1 (ISON)The Great Comet of 2013?
Seiic
hi Y
oshi
da
Swift – Bodewits et al. 2013
Thank You!