2009ApJ...702..929Z

We present a multi-wavelength photometric and spectroscopic study of a newly discovered candidate cluster [DBS2003] 45. Our H, Ks photometry confirms that [DBS2003] 45 is a cluster. An average visual extinction A_V∼ 7.1 ± 0.5 is needed to fit the cluster sequence with a model isochrone. Low-resolution spectroscopy indicates that half a dozen early B- and at least one late O-type giant stars are present in the cluster. We estimate the age of the cluster to be between 5 and 8 Myr based on spectroscopic analysis. Assuming an age of 6 Myr, we fit the observed mass function with a power law, N(M) ∝ M ^–Γ, and find an index Γ ∼ 1.27±0.15, which is consistent with the Salpeter value. We estimate that the total cluster mass is around 10³ M_☉ by integrating the derived mass function between 0.5 and 45 M_☉. Both mid-infrared and radio wavelength observations show that a bubble filled with ionized gas is associated with the cluster. The total ionizing photon flux estimated from radio continuum measurements is consistent with the number of hot stars we detected. Infrared bright point sources along the rim of the bubble suggest that there is triggered star formation at the periphery of the H II region.