Dust-temperature of an isolated star-forming cloud: Herschel observations of the Bok globule CB244

Abstract

We present Herschel observations of the isolated, low-mass star-forming Bok globule CB244. It contains two cold sources, a low-mass Class 0 protostar and a starless core, which is likely to be prestellar in nature, separated by 90" (~18 000 AU). The Herschel data sample the peak of the Planck spectrum for these sources, and are therefore ideal for dust-temperature and column density modeling. With these data and a near-IR extinction map, the MIPS 70 μm mosaic, the SCUBA 850 μm map, and the IRAM 1.3 mm map, we model the dust-temperature and column density of CB 244 and present the first measured dust-temperature map of an entire star-forming molecular cloud. We find that the column-averaged dust-temperature near the protostar is ~17.7 K, while for the starless core it is ~10.6 K, and that the effect of external heating causes the cloud dust-temperature to rise to ~17 K where the hydrogen column density drops below 10²¹ cm^-2. The total hydrogen mass of CB 244 (assuming a distance of 200 pc) is 15 ± 5 M_⊙. The mass of the protostellar core is 1.6 ± 0.1 M_⊙ and the mass of the starless core is 5 ± 2 M_⊙, indicating that ~45% of the mass in the globule is participating in the star-formation process.

Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.