Journal article, 2017

We present APEX 218 GHz observations of molecular emission in a complete sample of embedded protostars in the Ophiuchus star-forming region. To study the physical properties of the cores, we calculate H2CO and c-C3H2 rotational temperatures, both of which are good tracers of the kinetic temperature of the molecular gas. We find that the H2CO temperatures range between 16 K and 124 K, with the highest H2CO temperatures toward the hot corino source IRAS 16293-2422 (69-124 K) and the sources in the ? Oph A cloud (23-49 K) located close to the luminous Herbig Be star S1, which externally irradiates the ? Oph A cores. On the other hand, the c-C3H2 rotational temperature is consistently low (7-17 K) in all sources. Our results indicate that the c-C3H2 emission is primarily tracing more shielded parts of the envelope whereas the H2CO emission (at the angular scale of the APEX beam; 3600 au in Ophiuchus) mainly traces the outer irradiated envelopes, apart from in IRAS 16293-2422, where the hot corino emission dominates. In some sources, a secondary velocity component is also seen, possibly tracing the molecular outflow.

stars: formation

ISM: molecules


radiative transfer

ISM: individual objects (Ophiuchus)


Johan E. Lindberg

NASA Goddard Space Flight Center

S. B. Charnley

NASA Goddard Space Flight Center

J. K. Jorgensen

University of Copenhagen

M. A. Cordiner

Catholic University of America

NASA Goddard Space Flight Center

Per Bjerkeli

Chalmers, Earth and Space Sciences, Onsala Space Observatory

Astrophysical Journal

0004-637X (ISSN) 1538-4357 (eISSN)

Vol. 835 1 3- 3

Subject Categories

Physical Sciences



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5/8/2018 1