Paper detail

The Spitzer-IRAC Point Source Catalog of the Vela-D Cloud

This paper presents the observations of the Cloud D in the Vela Molecular Ridge, obtained with the IRAC camera onboard the Spitzer Space Telescope at the wavelengths λ= 3.6, 4.5, 5.8, 8.0 μm. A photometric catalog of point sources, covering a field of approximately 1.2 square degrees, has been extracted and complemented with additional available observational data in the millimeter region. Previous observations of the same region, obtained with the Spitzer MIPS camera in the photometric bands at 24 μm and 70 μm, have also been reconsidered to allow an estimate of the spectral slope of the sources in a wider spectral range. A total of 170,299 point sources, detected at the 5-sigma sensitivity level in at least one of the IRAC bands, have been reported in the catalog. There were 8796 sources for which good quality photometry was obtained in all four IRAC bands. For this sample, a preliminary characterization of the young stellar population based on the determination of spectral slope is discussed; combining this with diagnostics in the color-magnitude and color-color diagrams, the relative population of young stellar objects in the different evolutionary classes has been estimated and a total of 637 candidate YSOs have been selected. The main differences in their relative abundances have been highlighted and a brief account for their spatial distribution is given. The star formation rate has been also estimated and compared with the values derived for other star forming regions. Finally, an analysis of the spatial distribution of the sources by means of the two-point correlation function shows that the younger population, constituted by the Class I and flat-spectrum sources, is significantly more clustered than the Class II and III sources.