2010MNRAS.408.2487P

Using data from large-scale surveys, like 2MASS, GLIMPSE, MIPSGAL, VGPS, GRS and IPHAS, we performed a multiwavelength study of the interstellar medium in a region of about 20x20 arcmin2 towards the molecular cloud G35.2 - 0.74. Additionally, the Ap 2-1 nebula, which is seen in projection over the molecular cloud, was studied using optical data obtained with the 2.15-m telescope at CASLEO, Argentina. From the HI absorption study, we estimate a distance of ∼2kpc for Ap 2-1, confirming that the nebula is embedded in the south portion of the molecular cloud G35.2 - 0.74. Performing a photometric study and analysing the spectral energy distribution of the sources likely to be embedded in the cloud, we confirm that this region is very active in star formation, mainly towards the north, where we discover a cluster of young stellar objects. From the Hα and [Nii] lines, we obtain a radial velocity of v_LSR∼ 31 km/s for the Ap 2-1 nebula, in coincidence with the velocity of the molecular cloud. Finally, we conclude that Ap 2-1 is an HII region probably excited by an early B-type star.