Pinpointing a stellar X-ray flare using XMM-Newton and VLT/UVES Uwe Wolter Hamburger Sternwarte May 2008 J.U. Ness J. Robrade J.H.M.M. Schmitt

The observations: Synchronizing orbits, night-time visibility, instrument schedules, … 2006 October October 14 Speedy Mic‘s rotation VLT visibility XMM orbit 1254 XMM observations  50 ks XMM-Newton data VLT/UVES spectra

Kürster 1994 v sin i = 132 ± 2 km/s ( Wolter et al ) P = ± d ( Cutispoto et al ) The target: Speedy Mic (BO Mic) A single K-dwarf - ultrafast and highly active A giant flare (E > erg) DSS, d ≈ “

A „moderate“ flare in X-rays and optical  Total flare energy in soft X-rays: ~ erg ≈ 4.5 hours Wolter et al EPIC-pn Rotation Phase Ca K Equivalent width HαHα

Chromospheric emission Rotational Modulation Wolter & Schmitt 2005 Ca II K λ 3933 Ǻ

Evolution of Ca II K Line Profiles Rotation Phase Wavelength „unsharp masked“ Å Rotation Phase Wavelength 9.4 h A C B C A B 2006 flare

Flare heating and cooling Wolter, Robrade et al. 2008; Reale et al.2004  Loop half length 240,000 km ≈ 0.4 R * 0.5 · log EM [cm -3 ] log T [K]

A flare in a context <<<<<<<<<<< Wolter et al ESO PR Phase 3.9 Phase 4.2 Phase 4.6

X-ray flare sites can be localized by simultaneous optical / UV Doppler imaging Summary Wolter, Robrade, Schmitt & Ness 2008, A&A 478, L12 ESO Press Release 53/07 „Speedy Mic‘s Photograph“ 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)

Appendix

Outlook: Chromospheric heating events He I 5875, Ca II 3933 and XMM-pn at 300 s resolution Rotation Phase

A „solar-like“ spectrum Na D Ǻ Na D Ǻ H β Ǻ H α Ǻ Ca II K Ǻ Ca II H Ǻ Arcturus (α Boo, K1 III, T eff ≈ 5200 K ) (NOAO)

e.g. Deutsch 1958, Vogt & Penrod 1983, Wolter 2004 The Doppler imaging principle: Line profiles → spatial information

Speedy Mic vs. Sun Ultrafast rotation and high activity Valenti 2001, Sterzig & Schmitt 1997, Cardini et al. 2007, Balihunas et al Sun Speedy Mic

Lost and found

„Ultrafast rotators“

BO „Speedy“ Mic in 2002 (HD )

Aug 2 „6400 Å“

Aug 7 „6400 Å“

Photometry 2002 (SAAO)

The Prominences …

Evolution of H α (Aug 2) line profiles

H α (Aug 2) Ca II K (Aug 2)

H α (Aug 2) „A densely packed prominence system beyond co-rotation“ H α (July 19) Dunstone et al (adapted) r = 3.5 ± 0.6 R * r ≈ 5 ± 1.5 R * R k = 1.95 ± 0.07 R *

Collier Cameron & Robinson 1989 Donati et al RXJ ±4423 („post T Tauri“) H α emission AB Dor H α absorption transients Stellar prominences

The Plage(s) …

φ = 112° θ = 130° Localizing one stellar plage Ca II K (Aug 2)

„Localizing one (?) stellar plage“ φ = 112° θ = 130° φ = 72° θ = 99° (Aug 7) Ca II K (Aug 2)

The Flare …

APOD April 2006 „Astronomers love stars …“ „… and we have a fine one right near us.“ (Zirrin 1988) DOT HαHα

H α pre-flareH α flare (21:06 UT) Johns-Krull et al The 1993 March 6 solar flare

„Unfortunately, the observer was eating lunch when the flare began.“ GOES „soft X-ray“ 20:23

(near max.) Solar flare H α profiles

Another solar flare (H α – 0.5 Å) Zirrin 1988 (BBSO) „after peak“ higher density „raining down“