Observations of Dust and Gas in Perseus B1-E: A First Look at Core Formation
James Di Francesco, Phillipe Andre, Stefano Pezzuto, Jean-Philippe Bernard, Peter Martin, Michael Reid
We present Perseus B1-E, an anomalous clump in the Perseus Molecular Cloud with high extinction (AV >~ 5 mag) but no previously detected substructures (cores or young stellar objects). Herschel maps towards B1-E, however, show significant substructures at 160−500 microns. We fit modified blackbody functions to the 160−500 micron spectral energy distrubtions, and we find that B1-E is a cold clump (14.1±0.8 K) with a mean column density of (6.3±2.7)×1021 cm−2. We extract the most dense substructures for follow-up observations in NH3 (1,1), NH3 (2,2), CCS (2−1), and HC5N (9−8) line emission with the Green Bank Telescope (GBT). We detect NH3 (1,1) towards all nine targets, suggesting that B1-E contains dense gas (>~ 103 cm−3). In addition, we detect NH3 (2,2) emission towards B1-E2, which allow us to derive the kinetic temperature and excitation temperature of Tkin=10.3±0.4 K and Tex=4.4±0.3 K, respectively. Furthermore, B1-E2 appears to be near the limit for a gravitationally bound structure. Thus, Perseus B1-E is thus an excellent candidate for future studies of core-formation.