Astronomy and Astrophysics – Astrophysics – Solar and Stellar Astrophysics
Scientific paper
2009-04-21
Astronomy and Astrophysics
Astrophysics
Solar and Stellar Astrophysics
45 pages (17 figures), and full source table. Full resolution version available at http://www.cfa.harvard.edu/~bourke/rcw38/
Scientific paper
We present adaptive optics (AO) near-infrared (JHKs) observations of the deeply embedded massive cluster RCW 38 using NACO on the VLT. Narrowband AO observations centered at wavelengths of 1.28, 2.12, and 2.17 micron were also obtained. The area covered by these observations is about 0.5 pc square, centered on the O star RCW 38 IRS2. We use the JHKs colors to identify young stars with infrared excess. Through a detailed comparison to a nearby control field, we find that most of the 337 stars detected in all three infrared bands are cluster members (~317), with essentially no contamination due to background or foreground sources. Five sources have colors suggestive of deeply embedded protostars, while 53 sources are detected at Ks only; their spatial distribution with respect to the extinction suggests they are highly reddened cluster members. Detectable Ks-band excess is found toward 29 +/- 3 % of the stars. For comparison to a similar area of Orion observed in the near-infrared, mass and extinction cuts are applied, and the excess fractions redetermined. The resulting excesses are then 25 +/- 5 % for RCW 38, and 42 +/- 8 % for Orion. RCW 38 IRS2 is shown to be a massive star binary with a projected separation of ~500 AU. Two regions of molecular hydrogen emission are revealed through the 2.12 micron imaging. One shows a morphology suggestive of a protostellar jet, and is clearly associated with a star only detected at H and Ks, previously identified as a highly obscured X-ray source. Three spatially extended cometary-like objects, suggestive of photoevaporating disks, are identified, but only one is clearly directly influenced by RCW 38 IRS2. A King profile provides a reasonable fit to the cluster radial density profile and a nearest neighbor distance analysis shows essentially no sub-clustering.
Alves J. J.
Bourke Tyler L.
DeRose Kimberly L.
Gutermuth Robert A.
Megeath Thomas S.
No associations
LandOfFree
A VLT/NACO Study of Star Formation in the Massive Embedded Cluster RCW 38 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A VLT/NACO Study of Star Formation in the Massive Embedded Cluster RCW 38, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A VLT/NACO Study of Star Formation in the Massive Embedded Cluster RCW 38 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-371752