The Spitzer c2d survey of nearby dense cores. III. Low-mass star formation in a small group, L1251B

We present a comprehensive study of a low-mass star-forming region, L1251B, at wavelengths from the near-infrared to the millimeter. L1251B, in which only one protostar, IRAS 22376+7455, was known previously, is confirmed to be a small group of protostars on the basis of observations with the Spitzer Space Telescope. The most luminous source of L1251B is located 5" north of the IRAS position. A near-infrared bipolar nebula, which is not associated with the brightest object and is located at the southeast corner of L1251B, has been detected in the IRAC bands. OVRO and SMA interferometric observations indicate that the brightest source and the bipolar nebula source in the IRAC bands are deeply embedded disk sources. Submillimeter continuum observations with single-dish telescopes and the SMA interferometric observations suggest two possible prestellar objects with very high column densities. Outside of the small group, many young stellar object candidates have been detected over a larger region of 12' × 12'. Extended emission to the east of L1251B has been detected at 850µ m; this "east core" may be a site for future star formation since no point source has been detected with IRAC or MIPS. This region is therefore a possible example of low-mass cluster formation, where a small group of pre- and protostellar objects (L1251B) is currently forming, alongside a large starless core (the east core)