EPoS Contribution
EPoS Contribution
Systematic Search of Massive Clusters in NIR Photometric Surveys (and the Variety of Results)

Sebastian Ramirez
UAUA, Antofagasta, CL
Widefield and all-sky near infrared photometric surveys (such as 2MASS, GLIMPSE, UKIDS-GPS and Vista-VVV) are excellent tools for discovering the deeply embedded young and massive stellar population in the Milky Way. Thanks to these catalogues the census of massive clusters have improved in the last decade, but still less than a quarter of the expected objects in our Galaxy have been reported. Even if NIR photometric surveys are useful for unveiling cluster candidates, the confirmation as a linked population of stars requires additional data (spectroscopic or proper motions, for example). In this talk I will present two projects dedicated to the confirmation of young massive clusters candidates, derived from systematic search using 2MASS, UKIDS-GPS and VVV photometry. Using a set of photometric criteria, we favor the selection of candidates with OB-dwarfs, confirmed later using near-infrared mid-resolution spectroscopy. The spectroscopy have revealed massive stars in several evolutionary stages and a diversity of clusters derived from a same homogenous searching method. Some particular examples of our characterized young clusters with populations of massive stars will be presented in the talk.
Caption: The deeply embedded population of the cluster candidate Masgomas-6 is shown in the GLIMPSE false color image (top; blue=IRAC I1, green=IRAC I3, red=IRAC I4). The green squares and numbers show the position of the massive stars selected for the spectroscopic follow-up (bottom-right), using the photometric criteria. In the pseudocolor-magnitude Q_IR-K_S diagram (bottom-left), we see most of the massive stars located around Q_IR~0.
Collaborators:
A. Herrero, IAC, ES
J. Borissova, IFA-UdV, CL
A.-N. Chene, Gemini-North, US
Key publication

Suggested Session: Star formation "laws" and IMF