Survey of Young Stellar Objects Associated with Molecular Clouds

Abstract

We present the preliminary results of a survey in the near-infrared of young and massive stellar objects embedded in dense molecular clouds. The survey was conducted at the LNA, Brazil, in the J, H, and nbK bands, in the direction of IRAS sources with colors characteristic of compact HII regions that also present strong CS(2-1) line emission. The coordinates of the IRAS sources were improved to 1.9ⁿ resolution with the help of the MSX catalog, allowing us to associate them univocally to the detected stars in our sample. Several IR nebulae were detected, indicating also that young stellar clusters are being formed in the core of the molecular clouds. From the total number of 127 observed regions we found that 105 presented stars in the H band inside the IRAS error ellipse, and were associated to a MSX point source. We obtained the integrated bolometric luminosities and main-sequence spectral types of the detected stars, assuming that the bolometric luminosity coincided with the integrated IR luminosity, and using the fact that for massive stars the evolution towards the main sequence proceeds at constant luminosity. The Initial Mass Function of the sample follows a Salpeter’s law with index 1.6 between spectral types B0 and O3.