Pre--Main-Sequence Stars in the Serpens Molecular Cloud

The authors have mapped the central 10 arcmin² region of the Serpens molecular cloud at 2.2 μm with a spatial resolution of ≡7arcsec.5. More than 13 stars with K ⪉ 13.4 mag were detected in this area, only three of which have so far been identified with optical counterparts. Additional infrared photometry as well as spectrophotometry around 3.1 μm were obtained for the four brightest stars. The flux distributions of all four stars peak at approximately 3 μm, and the 3.07 μm "ice" feature was detected in absorption toward all four stars. The primary result of this study is the detection of at least three pre-main-sequence stars. The range of possible luminosities, radii, and temperatures for these stars as derived from the authors' near-infrared observations are consistent with those expected from models of low mass, pre-main-sequence stars. The near-infrared radiation is predicted to originate from circumstellar dust at a radius of up to 100 R_sun; with an effective temperature of ⪉2100K.