X-ray Emitting Young Stars in the L1551 Cloud
Session 9 -- Protostars, Young Stars and Stellar Accretion Disks
Display presentation, Monday, June 12, 1995, 9:20am - 6:30pm

## [9.05] X-ray Emitting Young Stars in the L1551 Cloud

L. Carkner, E. D. Feigelson (Penn State University), K. Koyama (Kyoto University), T. Montmerle (Center d'\'Etudes de Saclay)

Low mass pre-main sequence stars in the nearby Lynds 1551 star forming cloud cloud are studied with the $ROSAT$ and $ASCA$ X-ray satellites. An 8 ksec $ROSAT$ image reveals 38 sources including 7 well-known T Tauri stars, 14 potential new weak-lined T Tauri stars, 16 X-ray emitting stars unrelated to the cloud, and an active B9 star. A 40 ksec $ASCA$ image of the cloud detects seven of the $ROSAT$ sources.

Spectral fitting of the brighter X-ray emitting stars suggests the emission is produced in either a multi-temperature plasma, with temperatures near 0.2 and 1 keV, or a single-temperature plasma with low metal abundances. XZ Tau, a young classical T Tauri star, is much stronger in $ASCA$ than $ROSAT$ observations showing a harder (1.5-2.0 kev) component. Eleven $ROSAT$ sources exhibit variability of up to a factor of two on timescales of hours. A powerful flare, with total energy around 3 $\times$ $10^{34}$ ergs, is observed by $ASCA$ on the weak-lined T Tauri star V826 Tau.