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 Taur i star (WTTS) V410 Tau using the ROSAT PSPC. This deep exposure enable d 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 th at the PMS population in Taurus-Auriga is nearly completely known, thi s X-ray survey revealed eight new PMS objects in a region 50' in diame ter, as compared to a previously known stellar population of 12 object s, including deeply embedded IRAS sources. Spectroscopic and photometr ic observations enable us to place these objects in the H-R diagram. T he newly discovered objects are predominantly stars of spectral-type M O and later, and a large fraction (6/8) appear to be surrounded by cir cumstellar accretion disks as judged by their infrared excess and Halp ha emission. We combined the data for these X-ray-discovered objects w ith extant and new data for the previously identified PMS stars in thi s region to examine the history of star formation and the frequency di stribution of stellar masses in this cloud. If the ''post-ROSAT'' popu lation 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 m asses, 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 ma sses. The derived N(log M) for L1495E compares well with the IMF deriv ed from studies of stars in the solar neighborhood, a result which sug gests that the Taurus-Auriga clouds are currently producing stars whos e mass spectrum approximates the time/space-averaged IMF for the solar neighborhood.