The massive stellar population of W49: a spectroscopic survey

Where and how are massive stars forming in the Galaxy? Answering this question is hampered by their high extinction and short life times. Starburst clusters such as W49 where 100s of OB-type stars are present are exceptional laboratories to address these issues. W49 is one of the most luminous and youngest HII regions in our galaxy located at a distance of 11.4 kpc. The region consists of over 40 ultra-compact HII regions as well as a more extended Giant HII region. We present observations made by applying imaging and multi-object spectroscopy in the K-band of the high-mass stellar content of W49. These near-infrared observations are obtained with LUCI at the Large Binocular Telescope. The K-band spectra of the candidate massive stars provide us with more reliable spectral types than photometry alone. After spectroscopic classification (and applying the proper extinction law), the objects can be placed in a Hertzsprung-Russell diagram. With comparison to stellar evolution models, the age as well as the mass of the stellar population can be estimated. We present the first results of our spectroscopic campaign of W49 in this poster.