TY - GEN
T1 - Star Formation in the W49A Molecular Cloud: Birth of a Massive Star Cluster
AU - Homeier, N. L.
AU - Alves, J.
PY - 2004/12/1
Y1 - 2004/12/1
N2 - The W49A star-forming region is embedded in a 106
M⊙ molecular cloud, one of the most massive in our
Galaxy. It has been long known as one of the most luminous radio H II
regions, containing 30-40 compact and ultracompact H II regions and
several hot cores. We have detected a previously unknown massive star
cluster (Cluster 1) embedded in the W49 molecular cloud using JHKs
observations with SOFI+NTT. We find that the inferred mass of Cluster 1
is 1-2 × 104 M⊙, and is 2 pc in
projected distance from the largest grouping of ultracompact H II
regions (including the Welch ring). We use the extensive line-of-sight
extinction to isolate a population of objects associated with W49A, and
use this sample to obtain a mass function. The slope of the derived mass
function for objects associated with W49A, -1.3 ± 0.3, is
consistent with a Salpeter slope. About 3 pc away from the main
star-forming complexes seen in near-infrared and radio observations is
an ˜ 80 M⊙ star ionizing a compact H II region
(object CC). We obtained adaptive optics imaging with NACO on the VLT of
the 1.5 pc surrounding this object to search investigate the stellar
initial mass function in the vicinity of a massive star. On the global
molecular cloud scale in W49, massive star formation apparently did not
proceed in a single concentrated burst, but in small groups, or
subclusters.
AB - The W49A star-forming region is embedded in a 106
M⊙ molecular cloud, one of the most massive in our
Galaxy. It has been long known as one of the most luminous radio H II
regions, containing 30-40 compact and ultracompact H II regions and
several hot cores. We have detected a previously unknown massive star
cluster (Cluster 1) embedded in the W49 molecular cloud using JHKs
observations with SOFI+NTT. We find that the inferred mass of Cluster 1
is 1-2 × 104 M⊙, and is 2 pc in
projected distance from the largest grouping of ultracompact H II
regions (including the Welch ring). We use the extensive line-of-sight
extinction to isolate a population of objects associated with W49A, and
use this sample to obtain a mass function. The slope of the derived mass
function for objects associated with W49A, -1.3 ± 0.3, is
consistent with a Salpeter slope. About 3 pc away from the main
star-forming complexes seen in near-infrared and radio observations is
an ˜ 80 M⊙ star ionizing a compact H II region
(object CC). We obtained adaptive optics imaging with NACO on the VLT of
the 1.5 pc surrounding this object to search investigate the stellar
initial mass function in the vicinity of a massive star. On the global
molecular cloud scale in W49, massive star formation apparently did not
proceed in a single concentrated burst, but in small groups, or
subclusters.
M3 - Contribution to proceedings
SN - 1-58381-184-2
T3 - Astronomical Society of the Pacific conference series
SP - 365
EP - 369
BT - The Formation and Evolution of Massive Young Star Clusters
A2 - Lamers, Henny J.G.L.M.
PB - Astronomical Society of the Pacific
CY - San Francisco, Calif.
ER -