Spitzer Space Telescope imaging from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) reveals a previously unidentified low-latitude rich star cluster near l = 31°.3, b = -0°.1. Near-infrared JHK′ photometry from the Wyoming Infrared Observatory indicates an extinction of A v ≃ 15 ± 3 mag for cluster members. Analysis of 13CO features along the same sight line suggests a probable kinematic distance of 3.1-5.2 kpc. The new cluster has an angular diameter of ∼ 1-2 pc, a total magnitude corrected for extinction of m K0 = 2.1, and a luminosity of M K ≃ -10.3 at 3.1 kpc. In contrast to young massive Galactic clusters with ages less than 100 Myr, the new cluster has no significant radio emission. Comparison with theoretical K-band luminosity functions indicates an age of at least several gigayears and a mass of at least 10 5 M⊙. Unlike known old open clusters, this new cluster lies in the inner Galaxy at R GC ≃ 6.1 kpc. We designate this object "GLIMPSE-C01" and present evidence that it is a Milky Way globular cluster passing through the Galactic disk. We also identify a region of star formation and fan-shaped outflows from young stellar objects in the same field as the cluster. The cluster's passage through the Galactic molecular layer may have triggered this star formation activity.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science