A MULTIWAVELENGTH STUDY OF STAR-FORMATION IN THE L1495E CLOUD IN TAURUS

We have carried out a deep (t = 30,000 s) X-ray search of the eastern portion of the L1495 cloud centered on the well-known weak line T Tauri star (WTTS) V410 Tau using the ROSAT PSPC. This deep exposure enabled a search for candidate pre-main-sequence (PMS) objects in this cloud to a limit approximately 20 times more sensitive than that typical of the fields examined with the Einstein searches. Despite assertions that the PMS population in Taurus-Auriga is nearly completely known, this X-ray survey revealed eight new PMS objects in a region 50' in diameter, as compared to a previously known stellar population of 12 objects, including deeply embedded IRAS sources. Spectroscopic and photometric observations enable us to place these objects in the H-R diagram. The newly discovered objects are predominantly stars of spectral-type MO and later, and a large fraction (6/8) appear to be surrounded by circumstellar accretion disks as judged by their infrared excess and Halpha emission. We combined the data for these X-ray-discovered objects with extant and new data for the previously identified PMS stars in this region to examine the history of star formation and the frequency distribution of stellar masses in this cloud. If the ''post-ROSAT'' population is either complete or representative, we conclude (1) that star formation in L1495 East took place approximately 1 x 10(6) yr ago and that the spread in ages is small; (2) the frequency distribution of masses, N(M), in this apparently coeval group appears to peak near log M = -0.5 (using masses derived from recently published PMS tracks of D'Antona & Mazzitelli and Swenson et al. and to decline toward lower masses. The derived N(log M) for L1495E compares well with the IMF derived from studies of stars in the solar neighborhood, a result which suggests that the Taurus-Auriga clouds are currently producing stars whose mass spectrum approximates the time/space-averaged IMF for the solar neighborhood.