2000ApJ...540L..87S

We report the discovery of two distant embedded young stellar clusters located far in the outer Galaxy. The clusters are resolved in near-infrared images and seen as enhancements in the surface density of IR-excess stars centered close to IRAS 07255-2012. The clusters are embedded in a molecular cloud containing a CS dense core. The molecular cloud, as traced by CO (J=1-0) is elongated and extends over a region of 15x6 pc². From the millimeter observations, we derive a kinematic distance of 10.2 kpc and a Galactocentric distance of 16.5 kpc, making these clusters among the most distant embedded clusters in the Galaxy. The main (richer) cluster is well confined to a region of about 1.2 pc in radius. Down to our detection limit of about 1-2 M_☉ at this distance, it contains at least 30 members. The smaller cluster contains at least five stars. They all exhibit near-infrared color excesses consistent with young stellar objects having circumstellar and/or envelope material. We estimate that the star formation efficiency of this molecular cloud is about 4%-10%.