NIR Subarcsec Images of W49A: Uncovering the Beast
- Autor(en)
- Joao Alves, Nicole Homeier
- Abstrakt
We present subarcsecond J H and Ks images (FWHM ˜
0.5'') of an unbiased 5'×5' (16 pc × 16 pc) survey of the
densest region of the W49 giant molecular cloud. The observations
reveal 4 massive stellar clusters (with stars as massive as ˜ 120
M⊙) the larger (Cluster 1) about 3 pc East of the well
known Welch ring of ultra-compact HII regions. Cluster 1 is a)
extincted by at least AV > 20 mag of foreground (unrelated
and local) extinction b) has more than 30 magnitudes of internal
inhomogeneous extinction implying that it is still deeply buried in its
parental molecular cloud and c) is powering a 6 pc diameter giant HII
region seen both at the NIR and radio continuum. We also identify the
exciting sources of several UC HII regions. The census of massive stars
in W49A agrees or is 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(en)
- Institut für Astrophysik
- Externe Organisation(en)
- Joint ALMA Observatory
- Band
- 221
- Publikationsdatum
- 2004
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/75c01e38-ebb8-4ff4-9067-f7fc63efc5e3