Extreme Coronal Mass Ejections in Young Stars: Calibration of Solar Physics Relationships to

Investigate Angular Momentum Loss in T Tauri Stars

Keivan Guadalupe Stassun

Vanderbilt University

Sean Matt (CEA Saclay)W. Jeffrey Hughes and Sarah McGregor (Boston University)

Alicia N. Aarnio

University of Michigan

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 loops?

• Implications for angular momentum losses if loops destabilize?

Matt & Pudritz (2005)

Large flaring loops: Stabilized by magnetic star-disk interaction?

Aarnio, Stassun, & Matt (ApJ, 2010)

The value of full SED fitting…

• 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

Magnetic loop intersects disk (~20% of cases)

Aarnio, Stassun, & Matt (ApJ, 2010)

SED model grid from Robitaille et al (2006)

photosphere

HST

2MASSSpitzer IRAC

photosphere

loop height

Rtrunc > Rsub

Rtrunc = Rsub

No evident loop-disk interaction (~60% of cases)

Aarnio, Stassun & Matt (ApJ, 2010)

• Extreme flares are just the tip of the iceberg– Overall flare frequency from COUP:

1.5 flares per star in 13-day observation

Angular momentum losses from extreme CMEs

Aarnio et al. (Solar Phys., 2011)

- 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?

The trouble with halo CMEs …

Aarnio et al. (Solar Phys, 2011)

Aarnio et al. (Solar Phys, 2011)

Including halo CMEs 1,153 flare-CME pairs

Regime of TTS flares