Star formation at the edge of the optical disk of our Galaxy

We report a discovery of young stellar objects associated with a molecular cloud at the edge of the optical disk of our Galaxy, in the course of our near-infrared survey of distant molecular clouds in the outer Galaxy region. This cloud is denoted as Cloud 2 in the list by Digel at al. It is one of the most distant molecular clouds from the Galactic center known to date, with a probable Galactic radius of 15-19 kpc. Our results show that ongoing star formation is present in Cloud 2 and that active star formation can occur in the farthest regions of the Galaxy, where the molecular gas density is extremely low, perturbation from the spiral arms is very small, and the metallicity is similar to that for irregular dwarf galaxies. Cloud 2 as well as other Digel clouds is an excellent laboratory in which to study the details of the star formation process in an environment that is similar to that in the early stage of the formation of the Galactic disk.