The young massive stellar cluster associated with rcw 121.

• Grant number: 07/02874-7
• Support Opportunities: Regular Research Grants - Publications - Scientific article
• Start date: June 01, 2007
• End date: August 31, 2007
• Field of knowledge: Physical Sciences and Mathematics - Astronomy - Astrophysics of the Interstellar Medium
• Principal Investigator: Zulema Abraham
• Grantee: Zulema Abraham
• Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

We report near-infrared (NIR) broadband and narrowband photometric observations in the direction of the IRAS 17149-3916 source that reveal the presence of a young cluster of massive stars embedded in an H II region coincident with RCW 121. These observations, together with published radio data and Midcourse Space Experiment and Spitzer images, were used to determine some of the physical parameters of the region. We found 96 cluster member candidates in an area of about 1.5×2.0 arcmin2, 30% of them showing excess emission in the near-IR. IRS 1, the strongest source in the cluster with an estimated spectral type of O5 V-O6 V zero-age main sequence based on the color-magnitude diagram, is probably the main ionizing source of the H II region detected at radio wavelengths. Using the integrated Brγ and the 5 GHz flux densities, we derived a mean visual extinction AV=5.49+/-2.061.32 mag. From the observed size of the Brγ extended emission, we calculated the emission measure E=4.5×1024 cm-5 and the electron density ne=2.6×103 cm-3, characteristic of compact H II regions. (AU)