The Trumpler 14 photodissociation region in the Carina Nebula

Abstract

We report the results of observations of the fine- structure emission lines [ CII] 158 mu m and [ OI] 63 mu m using FIFI on the Kuiper Airborne Observatory ( KAO) and the Long Wavelength Spectrometer ( LWS) on board ISO, towards the molecular cloud associated with the stellar cluster Trumpler 14 ( Tr 14) in the Carina Nebula. These data are compared with selected CO and CS transitions obtained with the SEST as well as IRAS and MSX images to produce a detailed view of the morphology and the physical conditions prevailing in the photodissociation region ( PDR) at the interface between the ionized gas and the molecular dust lane. The relative intensity distribution observed for the various tracers is consistent with the stratification expected for a molecular cloud seen edge- on and exposed to a radiation field of approximate to 10(4) G(0), which is dominated by the most massive stars of Tr 14. The grain photoelectric heating efficiency, epsilon, is estimated to be approximate to 5 x 10(-3) and is comparable to other galactic PDRs. The molecular gas has a complicated velocity structure with a high velocity dispersion resulting from the impact of the stellar winds arising from Tr 14. There is evidence of small- scale clumping with a very low volume filling factor. Despite the rich concentration of massive O stars in Tr 14 we find that the parameters of the PDR are much less- extreme than those of the Orion and M 17 massive star- forming regions.