Star disk interactions in Xray flaring stars

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Transcript Star disk interactions in Xray flaring stars

Extreme Coronal Mass Ejections in Young Stars:
Calibration of Solar Physics Relationships to
Investigate Angular Momentum Loss in T Tauri Stars
N. Aarnio
Sean Matt (CEA Saclay)
W. Jeffrey Hughes and Sarah McGregor (Boston University)
Outstanding questions related to activity in
young stars
What produces extreme X-ray
emission in young stars?
Accretion (e.g. Kastner et al. 2002)
Scaled-up solar-type coronae
(e.g. Stassun et al. 2004, 2006, 2007)
What governs angular
momentum loss in young
low-mass stars?
Magnetic star-disk interaction
(e.g. Shu et al. 1994)
Scaled up solar-analog winds
(e.g. Barnes et al. 2007, Matt et al. 2010)
Matt & Pudritz (2005)
Chandra Orion Ultradeep Project (COUP)
1 Msec Chandra
observation of the
Orion Nebula Cluster
(Getman et al. 2005)
Nearly continuous
X-ray light curves of
~1600 young stars
spanning ~13 days
Simultaneous optical
light curves
(Stassun et al. 2006, 2007)
Flare analysis: Solar-type flaring loops
Uniform cooling loop (UCL)
modeling  physical parameters of
magnetic loop and confined plasma.
Favata et al. (ApJ 2005)
Extreme (and extremely large) flares in
young low-mass stars
----- 1-8Å
----- 0.5-4Å
The most energetic flares, if seen on
the Sun, would be X300 to X40,000!
0.1< Rloop/Rstar < 55
• Necessary conditions for
stability of large magnetic
• Implications for angular
momentum losses if loops
Large flaring loops:
Stabilized by magnetic star-disk interaction?
• Study sample: 32 most powerful
flaring stars (Favata et al 2005)
• SED modeling  disk structure
– Fluxes from 0.4 to 24 µm
(WFI, 2MASS, Spitzer)
– Compare inner disk radius to
magnetic flaring loop size
Matt & Pudritz (2005)
The value of full SED
Aarnio, Stassun, & Matt (ApJ, 2010)
Magnetic loop intersects disk (~20% of cases)
SED model grid from
Robitaille et al (2006)
Rtrunc > Rsub
Rtrunc = Rsub
loop height
Aarnio, Stassun, & Matt (ApJ, 2010)
No evident loop-disk interaction (~60% of cases)
Aarnio, Stassun & Matt
(ApJ, 2010)
Angular momentum losses from extreme CMEs
• Extreme flares are just the tip of the
– Overall flare frequency from COUP:
1.5 flares per star in 13-day observation
- LASCO CME database and GOES X-ray flare archives, 1996-2006
- 22,674 flares (12,050 with positions), 13,862 CMEs (7,741 with measured masses,
6,733 well constrained)
- 826 flare-CME pairs with well-measured CME masses
Aarnio et al. (Solar Phys., 2011)
Flare – CME Calibration: Evidence for Saturation?
Aarnio et al.
(Solar Phys, 2011)
The trouble with halo CMEs …
Aarnio et al.
(Solar Phys, 2011)
Including halo CMEs  1,153 flare-CME pairs
Regime of
TTS flares
Aarnio et al.
(Solar Phys, 2011)