2004/07/13 by A. G. Gibb, F. Wyrowski, Lee G. Mundy +1 · 2 citations
Chemistry · Earth and Planetary Sciences · Physics and Astronomy · #Astrophysics and Star Formation Studies #Atmospheric Ozone and Climate #Molecular Spectroscopy and Structure #astro-ph
paper · pdf · doi:10.1086/424810
published as Astrophys.J. 616 (2004) 301-318 · 24 pages including 13 figures. Accepted for publication in ApJ
arxiv created 2004/07/13 · openalex publication_date 2004/11/19 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We present observations made with the Berkeley-Illinois-Maryland Association millimeter array of the H 2 S 2(2,0) → 2(1,1) and C 18 O 2 → 1 transitions toward a sample of four hot molecular cores associated with ultracompact H II regions: G9.62+0.19, G10.47+0.03, G29.96-0.02, and G31.41+0.31. The angular resolution varies from 1 5 to 2 4, corresponding to scales of ~0.06 pc at the distance of these sources. High-velocity wings characteristic of molecular outflows are detected toward all four sources in the H 2 S line. In two cases (G29.96 and G31.41) red- and blueshifted lobes are clearly defined and spatially separate, indicating that the flows are collimated. We also confirm the previous detection of the outflow in G9.62F. Although the gas-phase H 2 S abundance is not well constrained, assuming a value of 10 -7 yields lower limits to total outflow masses of ~8 M ☉ , values that are consistent with the driving sources being massive protostars. Linear velocity gradients are detected in both C 18 O and H 2 S across G9.62, G29.96, and, to a lesser extent, G31.41. These gradients are observed to be at a different position angle to the outflow in G9.62F and G29.96, suggestive of a rotation signature in these two hot cores. Our observations show that these hot cores contain embedded massive protostellar objects that are driving bipolar outflows. Furthermore, the lack of strong centimeter-wave emission toward the outflow centers in G29.96 and G31.41 indicates that the outflow phase begins prior to the formation of a detectable ultracompact H II region.