The Carina Nebula and Gum 31 molecular complex – I. Molecular gas distribution, column densities, and dust temperatures

Abstract

We report high resolution observations of the 12 CO(1 → 0) and 13 CO(1 → 0) molecular lines in the Carina Nebula and the Gum 31 region obtained with the 22-m Mopra telescope as part of the The Mopra Southern Galactic Plane CO Survey. We cover 8 deg 2 from l = 285• to 290• , and from b = −1.5• to +0.5• . The molecular gas column density distributions from both tracers have a similar range of values. By fitting a grey-body function to the observed infrared spectral energy distribution from Herschel maps, we derive gas column densities and dust temperatures. The gas column density has values in the range from 6.3 × 10 20 to 1.4 × 10 23 cm −2 , while the dust temperature has values in the range from 17 to 43 K. The gas column density derived from the dust emission is approximately described by a log-normal function for a limited range of column densities. A high-column density tail is clearly evident for the gas column density distribution, which appears to be a common feature in regions with active star formation. There are regional variations in the fraction of the mass recovered by the CO emission lines with respect to the total mass traced by the dust emission. These variations may be related to changes in the radiation field strength, variation of the atomic to molecular gas fraction across the observed region, differences in the CO molecule abundance with respect to H 2 , and evolutionary stage differences of the molecular clouds that compose the Carina Nebula-Gum 31 complex.

Effect of Feedback of Massive Stars in the Fragmentation, Distribution, and Kinematics of the Gas in Two Star-forming Regions in the Carina Nebula

“…The Mopra CO images, combined with far-infrared data from Herschel, have allowed us to determine the overall molecular mass and its distribution across the CNC (Rebolledo et al 2016). We also reported significant dust temperature variations across the CNC, revealing the strong impact of the massive star clusters located at the center of the Nebula.…”

“…Table 3 gives the masses and sizes of each core identified in SP and NC. The former were computed assuming dust temperature values of 23 K for the SP and 28 K for the NC, both reported in Rebolledo et al (2016). We used a dust opacity κ 3mm = 0.186 cm 2 gr −1 computed from extrapolation of κ 1.3mm = 1 cm 2 gr −1 , and assuming β = 2.…”

“…Following the same approach detailed in Rebolledo et al (2016), we have fitted a log-normal function to the N-PDFs using Num(pixels) = Num peak × exp(− (ln(X) − ln(X peak )) 2 2 × δ 2 H2 ), (7) where X = N H2 and X peak = N H2,peak . The fit was conducted only using the bins in the range N H2,sen < N H2 < N H2,log , where N H2,sen is the column density sensitivity limit.…”

“…The strength of the FUV radiation in some regions of the NC can be ∼ 7000 G 0 which is 10 times larger than the radiation field observed in the SP (Brooks et al 2003;Roccatagliata et al 2013). The dust temperature map also shows differences between these two regions (Rebolledo et al 2016). While the dust temperature at the SP varies between ∼ 20 − 22 K, the NC shows dust temperatures ∼ 28 − 30 K. Thus, these two distinctive regions represent our best choice to investigate the effect of massive star feedback on the formation of new stars.…”

Carina’s pillars of destruction: the view from ALMA

“…Despite the importance of constraining cloud destruction, there has so far only been one study that has both spatially and spectrally resolved the kinematics of a single large pillar (Klaassen et al 2014), although see Rebolledo et al (2016) and Dawson et al (2011) for spectrally resolved studies of more than one pillar. The study of Klaassen et al, while providing a good proof of concept, could not constrain the general processes underlying ionised feedback and cloud disruption in general.…”