The X-Ray Emission of T Tauri Stars in Taurus-Auriga as Seen from the Einstein Observatory IPC

Abstract

We present a systematic study of the X-ray emission of pre-main-sequence stars in the Taurus-Auriga cluster. The sample consists of the 69 catalogued stars in this region observed with the Einstein Observatory, 53 of them have been identified with X-ray sources. The whole sample of the X-ray data, as given by the final processing, have been uniformly analyzed, and have been studied using X-ray luminosity functions, which take into account also non-detections. Our stars follow the trend of decreasing X-ray emission with age, well known for young late-type stars. Available data suggest that the average L _x of stars with companions is less than that of single stars; we discuss this in connection with the dependence of the coronal X-ray emission on rotation. Last, for strong emission-line stars, the (wind) Hα emission is inversely related to L _x, suggesting inhibition of the wind in the stars with bright coronae; in the weak-line stars, instead, a positive correlation of L _x with the emission lines supports their chromospheric origin.

This work was inspired by the late G.S. Vaiana, who has taken part to its early development. Without his contribution this paper would not have been in the present form.