The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) 2005:: A 4 deg2 Galactic plane survey in Vulpecula (l=59°)

We present the first results from a new 250, 350, and 500 mu m Galactic plane survey taken with the Balloon-borne Large-Aperture Submillimeter Telescope (BLAST) in 2005. This survey's primary goal is to identify and characterize high-mass protostellar objects (HMPOs). The region studied here covers 4 deg(2) near the open cluster NGC 6823 in the constellation Vulpecula (l = 59 degrees). We find 60 compact sources (< 60'' diameter) detected simultaneously in all three bands. Their SEDs are constrained through BLAST, IRAS, Spitzer MIPS, and MSX photometry, with inferred dust temperatures spanning similar to 12-40 K assuming a dust emissivity index beta = 1.5. The luminosity-to-mass ratio, a distance-independent quantity, spans similar to 0.2-130 L-circle dot M-circle dot(-1). Distances are estimated from coincident (CO)-C-13(1 -> 0) velocities combined with a variety of other velocity and morphological data in the literature. In total, 49 sources are associated with a molecular cloud complex encompassing NGC 6823 (distance similar to 2.3 kpc), 10 objects with the Perseus arm (similar to 8.5 kpc), and one object is probably in the outer Galaxy (similar to 14 kpc). Near NGC 6823, the inferred luminosities and masses of BLASTsources span similar to 40-10(4) L-circle dot and similar to 15-700M(circle dot), respectively. The mass spectrum is compatible with molecular gas masses in other high- mass star- forming regions. Several luminous sources appear to be ultracompact H ii regions powered by early B stars. However, many of the objects are cool, massive gravitationally bound clumps with no obvious internal radiation from a protostar, and hence excellent HMPO candidates.