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 (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 Comets off 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-ray Optical Dust (Continuum) Molecules NH 2, C 3, C 2, NH, OH, CS, H 2 Molecular ions CO +, H 2 O +, CO 2+,.. Energy Wavelength Atoms S, C, O, H UVFUVEUV Ions He +, He 2+, O 6+,.. Heavy Ions C 5,6+, O 7,8+,.. 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 Survey C,NOVIIOVIII A B C D E G F H X-ray spectra sample solar wind state low abundance of highly charged oxygen  cold wind high abundance of highly charged oxygen  hot wind Bodewits et al Solar wind freeze-in Temperature

Temperature vs. Freeze-in Temperature Bodewits et al. 2012

Bodewits et al Where is the Polar wind?

OVII and OVIII Ne X Ne IX Mg XI Mg XII Si XIII Bodewits et al. 2007; Ewing et al Fe XV - XX Comet emission > 1000 eV C/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 ACEChandra C6+/O7+2.1 ± ± 1.0 C5+/O7+7.6 ± 387 ± 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

Sasseen et al CHIPS+Chandra observations of Comet C/2001 Q4 (NEAT) Koutroumpa et al SWCX Model

Si Mg Si and Mg as temperature probes

2. The UltraViolet: Helium Rules!

OVI: elusive SWCX emission N(O 6+ ) = ~10 – 20 x N(O 7+ ) 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, nm

Most abundant ions in SW emit in EUV: O 6+ + H 2 O  O 5+ (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 1/10 th 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) He 2+ He + He 30.4 nm 58.4 nm He: The Coolest Ion of Them All

He II/He I Line Ratio HeHe + 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. 2010Dennerl 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 CO 2 (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? Seiichi Yoshida Swift – Bodewits et al. 2013

Thank You!