Allgemein

1
Pinpointing a stellar X-ray flare
using
XMM-Newton and VLT/UVES
J.U. Ness J. Robrade J.H.M.M. Schmitt
Uwe Wolter Hamburger Sternwarte May 2008
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The observations Synchronizing orbits,
night-time visibility, instrument schedules,
? 50 ks XMM-Newton data 142 VLT/UVES spectra
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The target Speedy Mic (BO Mic) A single K-dwarf
- ultrafast and highly active
P 0.380 0.004 d ( Cutispoto et al. 1997 )
v sin i 132 2 km/s ( Wolter et al. 2005 )
A giant flare (E gt 1036 erg)
Kürster 1994
DSS, d 0.0002
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A moderate flare in X-rays and optical
4.5 hours
Rotation Phase
Wolter et al. 2008
? Total flare energy in soft X-rays 1034 erg
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Chromospheric emission Rotational Modulation
Ca II K ? 3933 ?
Wolter Schmitt 2005
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Wavelength
Rotation Phase
Evolution of Ca II K Line Profiles
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Flare heating and cooling
? Loop half length 240,000 km 0.4 R
Wolter, Robrade et al. 2008 Reale et al.2004
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A flare in a context
Phase 4.2
Phase 3.9
Wolter et al. 2008
ESO PR 53-2007
Phase 4.6
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Summary

• X-ray flare sites can be localized by
  simultaneous optical / UV Doppler imaging

• Flare sites are not necessarily conspicuous
  otherwise

on returning within 60 seconds was
mortified to find that it was already much
enfeebled.
(R. Carringon 1859, MNRAS XX)
Wolter, Robrade, Schmitt Ness 2008, AA 478,
L12ESO Press Release 53/07 Speedy Mics
Photograph
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Appendix
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Outlook Chromospheric heating events
Rotation Phase
He I 5875, Ca II 3933 and XMM-pn at 300 s
resolution
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A solar-like spectrum
Ha 6562.81 ?
Na D2 5889.97 ?
Na D1 5895.94 ?
Hß 4861.34 ?
Ca II K 3933.68 ?
Ca II H 3968.49 ?
(NOAO)
Arcturus (a Boo, K1 III, Teff 5200 K )
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The Doppler imaging principle Line profiles ?
spatial information
e.g. Deutsch 1958, Vogt Penrod 1983, Wolter
2004
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Speedy Mic vs. Sun Ultrafast rotation and high
activity
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Lost and found
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Ultrafast rotators
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Ultrafast rotators
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BO Speedy Mic in 2002 (HD 197890)
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Aug 2 6400 Å
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Aug 7 6400 Å
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Photometry 2002 (SAAO)
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The Prominences
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Evolution of Ha (Aug 2) line profiles
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Ha (Aug 2)
Ca II K (Aug 2)
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A densely packed prominence system beyond
co-rotation
Ha (Aug 2)
Ha (July 19)
r 5 1.5 R
r 3.5 0.6 R
Rk 1.95 0.07 R
Dunstone et al. 2006 (adapted)
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Stellar prominences
Donati et al. 2000
Collier Cameron Robinson 1989
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The Plage(s)
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Localizing one stellar plage
f 112 ? 130
Ca II K (Aug 2)
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Localizing one (?) stellar plage
(Aug 7)
Ca II K (Aug 2)
f 72 ? 99
f 112 ? 130
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The Flare
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Ha
Astronomers love stars
(Zirrin 1988)
and we have a fine one right near us.
DOT
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The 1993 March 6 solar flare
Johns-Krull et al. 1997
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GOES soft X-ray
2023
Unfortunately, the observer was eating lunch
when the flare began.
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Solar flare Ha profiles
(near max.)
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after peak
Another solar flare (Ha 0.5 Å)
higher density
raining down
Zirrin 1988 (BBSO)