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X-ray irradiation Peter Wheatley and evaporation University of - - PowerPoint PPT Presentation
X-ray irradiation Peter Wheatley and evaporation University of - - PowerPoint PPT Presentation
X-ray irradiation Peter Wheatley and evaporation University of Warwick Contributors: Tom Louden, Vincent Bourrier, David Ehrenreich, Alain Lecavalier des Etangs Exoplanet evaporation HD209458 Ly-alpha Vidal-Madjar et al 2003 HD189733
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Lammer et al. 2003
Lx <= 10-3 Lbol
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Lecavalier des Etangs 2007
Energy-limited evaporation
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Pizzolato ¡et ¡al ¡2003 ¡ ¡
Stellar X-ray emission
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Pizzolato ¡et ¡al ¡2003 ¡ ¡
Stellar X-ray emission
Jackson, Davis & Wheatley 2012
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Evaporation influencing giant planet evolution?
Jackson, Davis & Wheatley 2012 Mass loss rate: Planet destruction limits:
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Evolved giant planets
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Ehrenreich & Desert 2011
How efficient is the evaporation?
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HD 209458b with XMM-Newton
Kashyap ¡et ¡al ¡2008 ¡ Penz ¡et ¡al ¡2008 ¡ Sanz-‑Forcada ¡et ¡al ¡2011 ¡
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EUV flux via high-excitation lines in the UV
HST COS spectrum of HD209458 Linsky et al 2010 EUV emission similar to quiet Sun LEUV = 9 x 1027 erg/s X-ray emission is lower than quiet Sun LX < 3 x 1026 erg/s Energy limited mass loss = 10 x 1010 g/s at 100% efficiency c.f. 8 x 1010 g/s lower limit from the same COS data
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XMM and Chandra spectra 1 MK + 8 MK
Evaporation efficiency of GJ436b
Ehrenreich, ¡Bourrier, ¡Wheatley ¡et ¡al, ¡2015 ¡
Mark Garlick/Warwick
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XMM and Chandra spectra 1 MK + 8 MK XMM Chandra 1 MK (EUV/X-ray) 8 MK (X-rays)
Evaporation efficiency of GJ436b
Ehrenreich, ¡Bourrier, ¡Wheatley ¡et ¡al, ¡2015 ¡
Mass loss ~ 5 x 108 g/s Requires only ~1% efficiency (assuming EUV scaling of Chadney+15) During 1 Gyr of saturated X-ray emission may have lost 10% of initial mass
Mark Garlick/Warwick
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HD189733b: variable atmospheric escape
Lecavelier des Etangs, Bourier, Wheatley et al, 2012
Swift XRT
Sept 2011
HST
Mass loss ~ 109 g s-1
April 2010 Sept2011
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X-ray transit
- bservations with
Chandra & XMM-Newton
Poppenhaeger, Schmitt & Wolk 2013
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Poppenhaeger, Schmitt, & Wolk 2013
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Summary
- Many hot Earths are probably evolved giant planets
- Very different evaporation efficiencies in different planets
– HD209458b highly efficient, >80% – GJ436b much less efficient, ~1% – Both are simultaneous measurements of irradiation and mass loss
- HD189733b
– mass loss is episodic – appears to be influenced by stellar flares – X-ray coverage helps disentangle activity from absorption
- X-ray transit of HD189733b not yet confirmed