YOUNG STELLAR CLUSTERS CONTAINING MASSIVE YOUNG STELLAR OBJECTS IN THE VVV SURVEY

• Published in: The Astronomical journal 2016-09, Vol.152 (3), p.74
• Main Authors: Borissova, J., Alegría, S. Ramírez, Alonso, J., Lucas, P. W., Kurtev, R., Medina, N., Navarro, C., Kuhn, M., Gromadzki, M., Retamales, G., Fernandez, M. A., Agurto-Gangas, C., Chené, A.-N., Minniti, D., Pena, C. Contreras, Catelan, M., Decany, I., Thompson, M. A., Morales, E. F. E., Amigo, P.
• Format: Article
• Language: English
• Subjects: ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CLASSIFICATION; COLOR; DIAGRAMS; ENERGY SPECTRA; infrared: stars; MASS; open clusters and associations: individual (VVV CL010, VVV CL012, VVV CL013, VVV CL059, [DBS20, [DBS2003] 93, [DBS2003] 100, [DBS2003] 130); RESOLUTION; STAR CLUSTERS; STAR EVOLUTION; stars: pre-main sequence; stars: variables: general; VARIABLE STARS; VARIATIONS; VISIBLE RADIATION
• ISSN: 0004-6256; 1538-3881; 1538-3881
• DOI: 10.3847/0004-6256/152/3/74

ABSTRACT The purpose of this research is to study the connections of the global properties of eight young stellar clusters projected in the Vista Variables in the Via Lactea (VVV) ESO Large Public Survey disk area and their young stellar object (YSO) populations. The analysis is based on the combination of spectroscopic parallax-based reddening and distance determinations with main-sequence and pre-main-sequence ishochrone fitting to determine the basic parameters (reddening, age, distance) of the sample clusters. The lower mass limit estimations show that all clusters are low or intermediate mass (between 110 and 1800 M ), the slope Γ of the obtained present-day mass functions of the clusters is close to the Kroupa initial mass function. The YSOs in the cluster's surrounding fields are classified using low resolution spectra, spectral energy distribution fits with theoretical predictions, and variability, taking advantage of multi-epoch VVV observations. All spectroscopically confirmed YSOs (except one) are found to be massive (more than 8 M ). Using VVV and GLIMPSE color-color cuts we have selected a large number of new YSO candidates, which are checked for variability and 57% are found to show at least low-amplitude variations. In few cases it was possible to distinguish between YSO and AGB classifications on the basis of light curves.