High resolution CO observation of massive star forming regions

¹ European Southern Observatory, Karl-Schwarzschild-Strasse 2, Garching, Germany
e-mail: pklaasse@eso.org
² Dept of Physics and Astronomy, McMaster University, Hamilton, Canada
³ Harvard-Smithsonian Center for Astrophysics, Cambridge, USA
⁴ Centro de Radioastronomia y Astrofisica UNAM, Morelia, Mexico
⁵ Academia Sinica, Institute of Astronomy & Astrophysics, Taipei, Taiwan
⁶ Department of Physics, National Taiwan University, Taipei, Taiwan

Received: 20 December 2010
Accepted: 29 March 2011

Abstract

Context. To further understand the processes involved in the formation of massive stars, we have undertaken a study of the gas dynamics surrounding three massive star forming regions. By observing the large scale structures at high resolution, we are able to determine properties such as driving source, and spatially resolve the bulk dynamical properties of the gas such as infall and outflow.

Aims. With high resolution observations, we are able to determine which of the cores in a cluster forming massive stars is responsible for the large scale structures.

Methods. We present CO observations of three massive star forming regions with known HII regions and show how the CO traces both infall and outflow. By combining data taken in two SMA configurations with JCMT observations, we are able to see large scale structures at high resolution.

Results. We find large (0.26–0.40 pc), massive (2–3 M_⊙) and energetic (13–17    ×    10⁴⁴ erg) outflows emanating from the edges of two HII regions suggesting they are being powered by the protostar(s) within. We find infall signatures in two of our sources with mass infall rates of order 10^-4 M_⊙ yr^-1.

Conclusions. We suggest that star formation is ongoing in these sources despite the presence of HII regions. We further conclude that the source(s) within a single HII region are responsible for the observed large scale structures; that these large structures are not the net effect of multiple outflows from multiple HII regions and hot cores.