2 millimeter observations of bright-rimmed clouds with IRAS point sources

We have made 2 mm continuum observations of 15 bright-rimmed clouds (BRCs) associated with IRAS point sources and S140 with the Nobeyama Bolometer Arr ay (NOBA) mounted on the 45 m telescope of Nobeyama Radio Observatory. Cont inuum emission was detected in five BRCs and in S140. These five BRCs are k nown to be associated with near-infrared YSO clusters, mostly on the side f acing toward the exciting star(s) and, therefore, are likely the sites of s mall-scale sequential star formation. The detected emission peaks of these five sources correspond to the IRAS positions within the positional errors, and the IRAS sources are considered to be protostars (Class 0/I-like sourc es) that were formed most recently in the BRCs. Four of them are clearly ex tended more than the telescope beam, suggesting the presence of circumstell ar structures. The circumstellar masses derived from the 2 mm continuum are similar to 5-90 M ., which are more massive than those of the nearby Class 0/I objects (less than or equal to 1 M .). This fact and the relatively la rge bolometric luminosities of these objects suggest that the mass of the c luster or star(s) most recently formed in these BRCs could be higher than t hose of the previously formed stars found in the near-infrared cluster. The comparisons with previous observations of Bok globules unassociated with b right rims and other objects are discussed. Most noteworthy is that the rat ios of the bolometric luminosity to the circumstellar mass are significantl y higher for these BRCs than for Bok globules.