Radio emission from ROSAT-discovered young stars in and around Taurus-Auriga

An 8.4 GHz VLA survey of 91 recently discovered lithium-rich late-type stars from the ROSAT All-Sky Survey and pointed observations is presented. These objects lie in the vicinity of the Taurus-Auriga star-forming region (d similar or equal to 140 pc); however, some are dispersed nearly 30 degrees from known active star-forming cloud cores. This sample represents a spatially complete, flux-limited population of X-ray-bright young stars both within and away from the primary Tau-Aur stellar nurseries. Of the 91 sources, 29 are detected in this radio survey with a sensitivity limit of similar to 0.15 mJy. If they are at the distance of the star-forming clouds, we find that 32% of widely distributed young stars with L-X greater than or equal to 5 x 10(28) ergs s(-1) have radio luminosity densities in excess of 3.5 x 10(15) ergs s(-1) Hz(-1). This detection rate, the ranges of radio and X-ray luminosities, and the L-R/L-X ratios are consistent with known young weak-lined T Tauri stars (ages similar to 10(6) yr) that reside within the Taurus molecular clouds, but they are considerably higher than a zero-age main-sequence population such as the Pleiades (age similar or equal to 7 x 10(7) yr). The radio properties thus support the pre-main-sequence classification of the stars. They fitted well among other active young stars on the empirical L-R versus L-X diagram, implying that solar-type gyrosynchrotron activity is the radio emission mechanism.