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Chandra observations during the last solar cycle

Cometary X-rays. Chandra observations during the last solar cycle. Dennis Bodewits. NASA GSFC. Outline. Intro Comets & Solar Wind Chandra & Comets Conclusions. Cometary X-rays. Solar Wind charge exchange Bright in X-ray and FUV Variable Crescent shape Common property

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Chandra observations during the last solar cycle

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  1. Cometary X-rays Chandra observations during the last solar cycle Dennis Bodewits NASA GSFC

  2. Outline • Intro Comets & Solar Wind • Chandra & Comets • Conclusions

  3. Cometary X-rays • Solar Wind charge exchange • Bright in X-ray and FUV • Variable • Crescent shape • Common property • of (nearby) comets • 0.2-1 GW • Line emission Lisse et al 1996

  4. Solar Wind • Northern Light!! • Per cm3: • 9 protons • 10 electrons • 0.5 He2+ • few Oq+,Cq+,Nq+,… • Wind types • Variability! • SOHO, ACE, Ulysses • !DATA AVAILABLE ONLINE! polar 700 km/s equatorial 400-700 km/s

  5. ~ 3AU Comets Haser model (Haser, 1957) dust tail ion tail

  6. 10 km Nucleus • 103 km Contact surface • 106 km Bowshock • 108 km Tails Interaction between comet and wind O(q-1)+ (adapted from Cravens ’00)

  7. Spectra Lisse et al. 2001; Beiersdorfer et al 2003 CV CVI NVI NVII OVII OVIII Solar wind ion -> O7+ Light emitting ion -> OVIII

  8. Chandra Comet Survey C,N OVII OVIII H E • Chandra ACIS • 8 comets (10 now) • 0.3-1.0 keV photons • 2000 - 2006 (2008) • Q = 9*1027 – 2*1029/s • D = 0.1 – 1.4 AU • Rh = 0.8 – 1.5 AU • |Lat| = 0 – 34 deg • Phase = 41 – 103 deg F G C A B D

  9. Spectral Shape 300 km/s 700 km/s Velocity variations ~ factor 1.5 105 km 104 km 103 km Collisional Opacity Can be important, but not within this survey

  10. Solar Wind Composition Comet X-ray spectra sample solar wind state T. Zurbuchen - ACE/SWICS

  11. Comets Probe the Solar Wind

  12. C/2002 C1 (Ikeya-Zhang) + CMEFirst detection of Mg XI-XII and Si XIII in comet spectrum Bodewits et al, A&A (2007).; Dennerl et al, in prep. OVII and OVIII Ne IX Mg XI Ne X Mg XII Si XIII Fe XV - XX

  13. 17P/Holmes in polar wind Kanata Observatory 7’x7’ record • Mayor outburst in Oct 2007 • Chandra 31 October 2007 • Q = 5E29 mol/s • Rh = 2.54 AU • Lat = +19 degrees record Bodewits et al (in prep)

  14. Conclusions Charge exchange emission provides new window on solar system plasma interactions • X-ray: H- and He-like C,N,O,Ne,Mg,Si • <300 eV? • Spectra: • State solar wind • Composition • EUV: Helium Charge exchange emission occurs anywhere hot and cold gasses collide

  15. Thank you. Dennis.Bodewits@nasa.gov

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