Discovery of a Distant Star Formation Region using GLIMPSE

Examination of early, in-orbit checkout (IOC) images of a portion of the Galactic plane obtained by the Infrared Array Camera (IRAC) aboard the Spitzer Space Telescope revealed the presence of an extended emis- sion nebula with internal structure. The Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) data show this nebula, located at l 42 and b 0N5, contains bright point sources and two nonstellar regions. Ancillary data sets were used to help reveal the nature of this nebula and its exciting objects. In particular, 13 CO J ¼ 1 ! 0 line emission mapped by the Galactic Ring Survey (GRS) shows molecular gas associated with the infrared nebula. The 13CO radial velocity yields a far-kinematic distance of 11.1 kpc to the nebula, since there is no evidence for H i self-absorption. At 11.1 kpc, the far-infrared luminosity of the nebula is 4:8;104 L , and the mass of its molecular cloud is 1:1;104 M . The spectral energy distribution rises steeply from 2.2 to 100 m with an absorption feature at 10 m, exhibiting the shape of a late Class 0 young stellar object (YSO). The radio continuum flux observed toward the nebula is consistent with the free-free emission from one or more massive YSOs (MYSOs) with spectral types in the range O9 to B0. This analysis demon- strates one technique the GLIMPSE team will use for revealing thousands of Galactic star formation regions. Subject headinggs: Galaxy: general — H ii regions — infrared: ISM — infrared: stars — stars: distances — stars: formation