New Low-Mass Members of the Taurus Star-forming Region*

摘要

Brice?o et al. recently used optical imaging, data from the Two-Micron All-Sky Survey (2MASS), and follow-up spectroscopy to search for young low-mass stars and brown dwarfs in 8 deg2 of the Taurus star-forming region. By the end of that study, there remained candidate members of Taurus that lacked the spectroscopic observations needed to measure spectral types and determine membership. In this work, we have obtained spectroscopy of the 22 candidates that have AV ≤ 8, from which we find six new Taurus members with spectral types of M2.75 through M9. The new M9 source has the second latest spectral type of the known members of Taurus (~0.02 M☉). Its spectrum contains extremely strong emission in Hα (Wλ ~ 950 ?), as well as emission in He I 6678 ? and the Ca II IR triplet. This is the least massive object known to exhibit emission in He I and Ca II, which together with the strong Hα are suggestive of intense accretion.