The gas temperature of starless cores in Perseus

Abstract

In this paper, we study the determinants of starless core temperatures in the Perseus molecular cloud. We use NH_3 (1,1) and (2,2) observations to derive core temperatures (T_(kin)) and data from the COMPLETE Survey of Star-Forming Regions and the c2d Spitzer Legacy Survey for observations of the other core and molecular cloud properties. The kinetic temperature distribution probed by NH_3 is in the fairly narrow range of ~ 9-15 K. We find that cores within the clusters IC348 and NGC1333 are significantly warmer than "field" starless cores, and T_(kin) is higher within regions of larger extinction-derived column density. Starless cores in the field are warmer when they are closer to Class 0/I protostars, but this effect is not seen for those cores in clusters. For field starless cores, T_(kin) is higher in regions in which the ^(13)CO line width and the 1.1 mm flux from the core are larger, and T_(kin) is lower when the the peak column density within the core and average volume density of the core are larger. There is no correlation between T_(kin) and ^(13)CO line width, 1.1 mm flux, density, or peak column density for those cores in clusters. The temperature of the cloud material along the line of sight to the core, as measured by CO or far-infrared emission from dust, is positively correlated with core temperature when considering the collection of cores in the field and in clusters, but this effect is not apparent when the two subsamples of cores are considered separately.

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