BLAST: THE MASS FUNCTION, LIFETIMES, AND PROPERTIES OF INTERMEDIATE MASS CORES FROM A 50 deg2 SUBMILLIMETER GALACTIC SURVEY IN VELA (l ≈ 265°)

We present first results from an unbiased 50 deg(2) submillimeter Galactic survey at 250, 350, and 500 mu m from the 2006 flight of the Balloon-borne Large Aperture Submillimeter Telescope. The map has resolution ranging from 36 '' to 60 '' in the three submillimeter bands spanning the thermal emission peak of cold starless cores. We determine the temperature, luminosity, and mass of more than 1000 compact sources in a range of evolutionary stages and an unbiased statistical characterization of the population. From comparison with (CO)-O-18 data, we find the dust opacity per gas mass,kappa r = 0.16 cm(2) g(-1) at 250 mu m, for cold clumps. We find that 2% of the mass of the molecular gas over this diverse region is in cores colder than 14 K, and that the mass function for these cold cores is consistent with a power law with index alpha = -3.22 +/- 0.14 over the mass range 14M(circle dot) < M < 80 M-circle dot. Additionally, we infer a mass-dependent cold core lifetime of t(c)(M) = 4 x 10(6)(M/20M(circle dot))(-0.9) yr-longer than what has been found in previous surveys of either low or high-mass cores, and significantly longer than free fall or likely turbulent decay times. This implies some form of non-thermal support for cold cores during this early stage of star formation.