Far infrared observations of the southern Galactic star forming complex around IRAS 09002-4732

Abstract

The Galactic star forming region in the southern sky, associated with IRAS 09002-4732 has been mapped simultaneously in two far infrared bands (lambda _eff = 148 & 209 mu m), with ~ 1 arcmin angular resolution. Fifteen sources, including IRAS 08583-4719, 08589-4714, 09002-4732 and 09014-4736 have been detected, some of which are well resolved. Taking advantage of similar beams in the two bands, a reliable dust temperature [T(148/209)] map has been obtained, which detects colder dust (< 30 K) in this region. The HIRES processed IRAS maps at 12, 25, 60 and 100 mu m, have also been used for comparison. The optical depth maps, tau ₂₀₀ and tau ₁₀₀, generated from these far-IR data quantify the spatial distribution of the dust. The diffuse emission from this entire region has been found to be 35% of the total FIR luminosity. The slope of the IMF in the mass range 4-16 M_sun has been estimated to be -1.25^+0.75_-0.65 for this star forming complex. Radiative transfer models in spherical geometry have been explored to fit available observations of the 4 IRAS sources and extract various physical parameters for corresponding dust-gas clouds. Whereas a constant (r⁰) radial density distribution is favoured in IRAS 08583-4719, 08589-4714 and 09002-4732, the r^-1 law is inferred for IRAS 09014-4736. The dust composition is found to be similar (Silicate dominated) in all four IRAS sources modelled. The luminosity per unit mass is found to be in the narrow range of 44 - 81 L_sun/M_sun for these star forming regions.