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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. 2006 October 14. 2006 October 15. Speedy Mic‘s rotation. XMM orbit 1254. VLT visibility. XMM observations.

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slide1
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

slide2
2006 October 14

2006 October 15

Speedy Mic‘s rotation

XMM orbit 1254

VLT visibility

XMM observations

The observations: Synchronizing orbits, night-time visibility, instrument schedules, …

 50 ks XMM-Newton data + 142 VLT/UVES spectra

slide3
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 sini = 132 ± 2 km/s

( Wolter et al. 2005 )

A giant flare (E > 1036 erg)

Kürster 1994

DSS, d ≈ 0.0002“

slide4
CaKEquivalent width

EPIC-pn

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

slide5
Chromospheric emissionRotational Modulation

Ca II Kλ3933 Ǻ

Wolter & Schmitt 2005

slide6
A

2006 flare

C

C

9.4 h

B

B

Rotation Phase

A

1.7 Å@ 4000 Å

Wavelength

„unsharp masked“

Wavelength

Rotation Phase

Evolution of

CaIIK

Line Profiles

slide7
log T [K]

0.5 · log EM [cm-3]

Flare heating and cooling

 Loop half length

240,000 km

≈ 0.4 R*

Wolter, Robrade et al. 2008; Reale et al.2004

slide8
<<<<<<<<<<<

A flare in a context

Phase 4.2

Phase 3.9

Wolter et al. 2008

ESO PR 53-2007

Phase 4.6

slide9
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, A&A 478, L12ESO Press Release 53/07 „Speedy Mic‘s Photograph“

slide11
Outlook: Chromospheric heating events

Rotation Phase

He I 5875, Ca II 3933 and XMM-pn at 300 s resolution

slide12
A „solar-like“ spectrum

Hα6562.81 Ǻ

Na D25889.97 Ǻ

Na D15895.94 Ǻ

Hβ4861.34 Ǻ

Ca II K 3933.68 Ǻ

Ca II H 3968.49 Ǻ

(NOAO)

Arcturus (α Boo, K1 III, Teff ≈ 5200 K )

slide13
The Doppler imaging principle:

Line profiles → spatial information

e.g. Deutsch 1958, Vogt & Penrod 1983, Wolter 2004

slide14
Speedy Mic vs. SunUltrafast rotation and high activity

Sun

SpeedyMic

Valenti 2001, Sterzig & Schmitt 1997, Cardini et al. 2007, Balihunas et al. 1995

slide19
Aug 2

„6400 Å“

slide20
Aug 7

„6400 Å“

slide24
Hα(Aug 2)

CaII K (Aug 2)

slide25
„A densely packed prominence system beyond co-rotation“

Hα(Aug 2)

Hα(July 19)

r ≈ 5 ± 1.5 R*

r = 3.5 ± 0.6 R*

Rk = 1.95 ± 0.07 R*

Dunstone et al. 2006 (adapted)

slide26
RXJ 1508.6±4423 („post T Tauri“)

Hα emission

AB Dor

Hα absorption transients

Stellar prominences

Donati et al. 2000

Collier Cameron & Robinson 1989

slide28
Localizing one stellar plage

φ = 112° θ = 130°

CaIIK(Aug 2)

slide29
„Localizing one (?) stellar plage“

(Aug 7)

CaIIK(Aug 2)

φ = 72°

θ = 99°

φ = 112°

θ = 130°

slide31
APOD April 2006

„Astronomers love stars …“

(Zirrin 1988)

„… and we have a fine one right near us.“

DOT

slide32
Hα pre-flare

Hα flare (21:06 UT)

The 1993 March 6 solar flare

Johns-Krull et al. 1997

slide33
GOES „soft X-ray“

20:23

„Unfortunately, the observer was eating lunch when the flare began.“

slide35
„after peak“

Another solar flare

(Hα – 0.5 Å)

higher density

„raining down“

Zirrin 1988 (BBSO)

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