Journal Article

JCMT HARP CO 3–2 observations of molecular outflows in W5

Adam Ginsburg, John Bally and Jonathan P. Williams

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 418, issue 4, pages 2121-2144
Published in print December 2011 | ISSN: 0035-8711
Published online December 2011 | e-ISSN: 1365-2966 | DOI:
JCMT HARP CO 3–2 observations of molecular outflows in W5

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New James Clerk Maxwell Telescope (JCMT) HARP CO 3–2 observations of the W5 star forming complex are presented, totalling an area of ∼12 000 arcmin2 with sensitivity better than 0.1 K per 0.4 km s−1 channel. We discovered 55 CO outflow candidates, of which 40 are associated with W5 and 15 are more distant than the Perseus arm. Most of the outflows are located on the periphery of the W5 H ii region. However, two outflow clusters are >5 pc from the ionization fronts, indicating that their driving protostars formed without directly being triggered by the O-stars in W5. We compare the derived outflow properties to those in Perseus and find that the total W5 outflow mass is surprisingly low given the cloud masses. The outflow mass deficiency in the more massive W5 cloud [M(H2) ∼ 5 × 104 M] can be explained if ionizing radiation dissociates molecules as they break out of their host cloud cores. Although CO J = 3–2 is a good outflow tracer, it is likely to be a poor mass tracer because of sub-thermal line excitation and high opacity, which may also contribute to the outflow mass discrepancy. It is unlikely that outflows could provide the observed turbulent energy in the W5 molecular clouds even accounting for undetected outflow material. Many cometary globules have been observed with velocity gradients from head to tail, displaying strong interaction with the W5 H ii region and exhibiting signs of triggered or revealed star formation in their heads. Because it is observed face-on, W5 is an excellent region to study feedback effects, both positive and negative, of massive stars on star formation.

Keywords: stars: formation; ISM: individual objects: W5; ISM: jets and outflows; ISM: kinematics and dynamics

Journal Article.  13622 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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