Uncovering the Beast: The Galactic Starburst Region W49A

Author(s)

N. Homeier, J. Alves

Abstract

We present J, H, and Ks images of an unbiased 5‧ x 5‧ (16 pc

x 16 pc) survey of the densest region of the W49 giant molecular cloud.

The observations reveal a massive stellar cluster (Cluster 1) about 3 pc

East of the well-known Welch ring of ultra-compact H II regions, as well

as three smaller clusters associated with compact sources of radio

emission. Cluster 1 powers a 6 pc diameter giant H II region seen at

both the NIR and radio continuum, and has more than 30 visual magnitudes

of internal imhomogeneous extinction, implying that it is still deeply

embedded in its parent molecular cloud. The census of massive stars in

W49A agrees or slightly overabundant when compared with the number of

Lyman continuum photons derived from radio observations. We argue that

although the formation of the Welch ring could have been triggered by

Cluster 1, the entire W49A starburst region seems to have been

multi-seeded instead of resulting from a coherent trigger.

Organisation(s)

Department of Astrophysics

External organisation(s)

European Southern Observatory (Germany)

Journal

Bulletin of the American Astronomical Society

Volume

Pages

568

ISSN

0002-7537

Publication date

12-2002

Austrian Fields of Science 2012

103004 Astrophysics

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