THE INTERMEDIATE-MASS STAR-FORMING REGION LYNDS 1340. AN OPTICAL VIEW

Abstract

ABSTRACT We have performed an optical spectroscopic and photometric search for young stellar objects associated with the molecular cloud Lynds 1340, and examined the structure of the cloud by constructing an extinction map, based on SDSS data. The new extinction map suggests a shallow, strongly fragmented cloud, having a mass of some 3700 M ☉. Longslit spectroscopic observations of the brightest stars over the area of L1340 revealed that the most massive star associated with L1340 is a B4-type, ∼5 M ☉ star. The new spectroscopic and photometric data of the intermediate-mass members led to a revised distance of pc, and revealed seven members of the young stellar population with M ≳ 2 M ☉. Our search for Hα emission line stars, conducted with the Wide Field Grism Spectrograph 2 on the 2.2 m telescope of the University of Hawaii and covering a 30′ × 40′ area, resulted in the detection of 75 candidate low-mass pre-main sequence stars, 58 of which are new. We constructed spectral energy distributions (SEDs) of our target stars, based on SDSS, 2MASS, Spitzer, and WISE photometric data, derived their spectral types, extinctions, and luminosities from BVRIJ fluxes, estimated masses by means of pre-main sequence evolutionary models, and examined the disk properties utilizing the 2–24 μm interval of the SED. We measured the equivalent width of the Hα lines and derived accretion rates. The optically selected sample of pre-main sequence stars has a median effective temperature of 3970 K, a stellar mass of 0.7 M ☉, and an accretion rate of 7.6 × 10−9 M ☉ yr−1.