A submillimeter view of star formation near the H II region KR 140.
KERTON C.R., MARTIN P.G., JOHNSTONE D. and BALLANTYNE D.R.
Abstract (from CDS):
We present the results of 450 and 850 µm continuum mapping of the H II region KR 140 using the Submillimeter Common-User Bolometer Array (SCUBA) instrument on the James Clerk Maxwell Telescope (JCMT). KR 140 is a small (5.7 pc diameter) H II region at a distance of 2.3±0.3 kpc. Five of the six IRAS point sources near KR 140 were mapped in this study. Our analysis shows that two of these IRAS sources are embedded late B-type stars lying well outside the H II region, two are a part of the dust shell surrounding the H II region, and one is the combined emission from an ensemble of smaller sources unresolved by IRAS. We have discovered a number of relatively cold submillimeter sources not visible in the IRAS data, ranging in size from 0.2 to 0.7 pc and in mass from 0.5 to 130 M☉. The distribution of masses for all sources is well characterized by a power law N(>M)∝M–α with α=0.5±0.04, in agreement with the typical mass function for clumped structures of this scale in molecular clouds. Several of the submillimeter sources are found at the H II molecular gas interface and have probably been formed as the result of the expansion of the H II region. Many of the submillimeter sources we detect are gravitationally bound and most of these follow a mass-size relationship expected for objects in virial equilibrium with nonthermal pressure support. Upon the loss of nonthermal support, they could be sites of star formation. Along with the two B stars that we have identified as possible cluster members along with VES 735, we argue that five nearby highly reddened stars are in a pre-main-sequence stage of evolution.
ISM: H II Regions - ISM: Clouds - Stars: Formation - Submillimeter
Table 2: KMJB NNa (Nos 1-6, 6a-6c, 7-22).