A deep and wide-field view at the IC 2944/2948 complex in Centaurus

Abstract

We employed the ESO MPI wide-field camera and obtained deep images in the VIC passbands in the region of the IC 2944/2948 complex (l∼294.º 8; b∼−1.6º), and complemented them with literature and archival data. We used this material to derive the photometric, spectroscopic and kinematic properties of the brightest (V < 16) stars in the region. The VI deep photometry on the other end, helped us to unravel the lower main sequence of a few, possibly physical, star groups in the area. Our analysis confirmed previous suggestions that the extinction toward this line of sight follows the normal law (RV=3.1). We could recognize B-type stars spread in distance from a few hundred pc to at least 2 kpc. We found two young groups (age∼3 Myr) located respectively at about 2.3 and 3.2 kpc from the Sun. They are characterized by a significant variable extinction (E(B−V) ranging from 0.28 to 0.45 mag), and host a significant pre-main sequence population. We computed the initial mass functions for these groups and obtained slopes Gamma from -0.94 to -1.02 (e_Gamma=0.3), in a scale where the classical Salpeter law is -1.35. We estimated the total mass of both main stellar groups in ∼1100 and ∼500 M_sun, respectively. Our kinematic analysis indicated that both groups of stars deviate from the standard rotation curve of the Milky Way, in line with literature results for this specific Galactic direction. Finally, along the same line of sight we identified a third group of early-type stars located at ∼8 kpc from the Sun. This group might be located in the far side of the Sagittarius-Carina spiral arm.