We report observations of dust continuum emission at 1.2 mm towards the star forming region NGC 6334 made with the SEST SIMBA bolometer array. The observations cover an area of ∼ 2 square degrees with approximately uniform noise. We detected 181 clumps spanning almost three orders of magnitude in mass (3M −6 × 10 3 M ) and with sizes in the range 0.1-1.0 pc. We find that the clump mass function dN/d log M is well fit with a power law of the mass with exponent −0.6 (or equivalently dN/dM ∝ M −1.6 ). The derived exponent is similar to those obtained from molecular line emission surveys and is significantly different from that of the stellar initial mass function. We investigated changes in the mass spectrum by changing the assumptions on the temperature distribution of the clumps and on the contribution of free-free emission to the 1.2 mm emission, and found little changes on the exponent. The Cumulative Mass Distribution Function is also analyzed giving consistent results in a mass range excluding the high-mass end where a power-law fit is no longer valid. The masses and sizes of the clumps observed in NGC 6334 indicate that they are not direct progenitors of stars and that the process of fragmentation determines the distribution of masses later on or occurs at smaller spatial scales.The spatial distribution of the clumps in NGC 6334 reveals clustering which is strikingly similar to that exhibited by young stars in other star forming regions. A power law fit to the surface density of companions gives Σ ∝ θ −0.62 .

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.

We present high spatial resolution observations of giant molecular clouds (GMCs) in the eastern part of the nearby spiral galaxy NGC 6946 obtained with the Combined Array for Research in Millimeter-wave Astronomy (CARMA). We have observed CO(1 → 0), CO(2 → 1) and 13 CO(1 → 0), achieving spatial resolutions of 5. 4 × 5. 0, 2. 5 × 2. 0, and 5. 6 × 5. 4, respectively, over a region of 6 × 6 kpc. This region extends from 1.5 kpc to 8 kpc galactocentric radius, thus avoiding the intense star formation in the central kpc. We have recovered short-spacing u-v components by using single dish observations from the Nobeyama 45 m and IRAM 30 m telescopes. Using the automated CPROPS algorithm, we identified 45 CO cloud complexes in the CO(1 → 0) map and 64 GMCs in the CO(2 → 1) maps. The sizes, line widths, and luminosities of the GMCs are similar to values found in other extragalactic studies. We have classified the clouds into on-arm and inter-arm clouds based on the stellar mass density traced by the 3.6 μm map. Clouds located on-arm present in general higher star formation rates than clouds located in inter-arm regions. Although the star formation efficiency shows no systematic trend with galactocentric radius, some on-arm clouds-which are more luminous and more massive compared to inter-arm GMCs-are also forming stars more efficiently than the rest of the identified GMCs. We find that these structures appear to be located in two specific regions in the spiral arms. One of them shows a strong velocity gradient, suggesting that this region of high star formation efficiency may be the result of gas flow convergence.

Complementing the observations on the eastern part of galaxy NGC 6946 presented in a previous work, we report high spatial resolution observations of Giant Molecular Clouds (GMCs) in the nearby spiral galaxies M101 and NGC 628 obtained with the Combined Array for Research in Millimeter-wave Astronomy (CARMA). We observed CO(1 → 0) over regions with active star formation extending from 2 kpc to 15 kpc galactocentric radius. Higher resolution observations of CO(2 → 1) toward the brightest regions observed in CO(1 → 0) have allowed us to resolve some of the largest GMCs. We have recovered short-spacing u-v components by using single dish observations from the Nobeyama 45m and IRAM 30m telescopes. Using the automated CPROPS algorithm we identified 112 CO complexes in the CO(1 → 0) maps and 144 GMCs in the CO(2 → 1) maps. Using a Bayesian fitting approach, we generate scaling relations for the sizes, line widths, and virial masses of the structures identified in this work. We do not find evidence for a tight power law relation between size and line width, although the limited dynamic range in cloud size remains a clear issue in our analysis. Additionally, we use a Bayesian approach to analyze the scaling relation between the star formation and molecular gas surface density, known as the Kennicutt-Schmidt relation. When we perform our analysis using the boundaries of the structures identified by CPROPS, we find that the distribution of slopes are broadly distributed, mainly due to the limited dynamic range of our measured Σ H2 . In the case of the CO(1 → 0) complexes, the slope distributions are most consistent with super-linear relations, although sub-linear relations cannot be excluded for NGC 628 and NGC 6946. The GMCs from higher resolution CO(2 → 1) maps follow a similar behavior, but with larger scatter. As a complementary study, we use the Bayesian approach to analyze the Kennicutt-Schmidt relation for a uniform grid covering the areas surveyed, and with Σ H2 non-detections included in the analysis. The distributions of slopes is consistent with sub-linear relations for NGC 6946 and NGC 628, but is less constrained for M101. This picture is preserved after a 24µm background component is subtracted from the Σ SFR measurements. On-arm regions tend to have higher star formation rates than inter-arm regions. Similar to what we find in our study of the eastern part of NGC 6946, in M101 we find regions where the star formation efficiency (SFE) shows marked peaks at specific galoctocentric radii. On the other hand, the distribution of SFE in NGC 628 is more contiguous. We hypothesize that differences in the distribution of SFE may be indicative of different processes driving the spiral structure.