A Multiwavelength Study of Star Formation in the L1495E Cloud in Taurus

We have carried out a deep (t=30000s) 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 ∼ 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 8 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 HR Diagram. The newly discovered objects are predominantly stars of spectral type M0 and later, and a large fraction (6/8) appear to be surrounded by circumstellar accretion disks as judged by their infrared excess and Hα 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 ∼ 1× 10 yrs 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 logM = −0.5 (using masses derived from the recently published PMS tracks of D’Antona & Mazzitelli (1993) and Swenson et al. (1993)) 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. Subject headings: stars:formation, stars:pre-main sequence, circumstellar matter, X-rays:stars Visiting Astronomer, Kitt Peak National Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation.