Context. The Carina region is an excellent astrophysical laboratory for studying the feedback mechanisms of newly born, very massive stars within their natal giant molecular clouds (GMCs) at only 2.35 kpc distance. Aims. We use a clumpy PDR model to analyse the observed intensities of atomic carbon and CO and to derive the excitation conditions of the gas.Methods. The NANTEN2-4 m submillimeter telescope was used to map the [C i] 3 P 1 − 3 P 0 , 3 P 2 − 3 P 1 and CO 4-3, 7-6 lines in two 4 × 4 regions of Carina where molecular material interfaces with radiation from the massive star clusters. One region is the northern molecular cloud near the compact OB cluster Tr 14, and the second region is in the molecular cloud south of η Car and Tr 16. These data were combined with 13 CO SEST spectra, HIRES/IRAS 60 µm and 100 µm maps of the FIR continuum, and maps of 8 µm IRAC/Spitzer and MSX emission. Results. We used the HIRES far-infrared dust data to create a map of the FUV field heating the gas. The northern region shows an FUV field of a few 10 3 in Draine units while the field of the southern region is about a factor 10 weaker. While the IRAC 8 µm emission lights up at the edges of the molecular clouds, CO and also [C i] appear to trace the H 2 gas column density. The northern region shows a complex velocity and spatial structure, while the southern region shows an edge-on PDR with a single Gaussian velocity component. We constructed models consisting of an ensemble of small spherically symmetric PDR clumps within the 38 beam (0.43 pc), which follow canonical power-law mass and mass-size distributions. We find that an average local clump density of 2 × 10 5 cm −3 is needed to reproduce the observed line emission at two selected interface positions. Conclusions. Stationary, clumpy PDR models reproduce the observed cooling lines of atomic carbon and CO at two positions in the Carina Nebula.

Abstract. The hyperfine lines of an ammonia (1,1) inversion transition often exhibit anomalous intensity ratios towards star-forming cores. It has been known that the anomaly is only partially attributable to a non-LTE effect on the hyperfine transitions. In an attempt to investigate how systematic motion like expansion and contraction affect the line anomaly, whose existence is quite likely in star-forming cores, we have carried out radiative transfer calculations fully taking into account the hyperfine splitting of energy levels and the line overlap effect caused by the systematic motion. It is demonstrated that in a bundle of transitions from the (2,2) to (1,1) levels, photons emitted from one transition can be absorbed by another transition due to the systematic motion and the small frequency differences among the hyperfine transitions, resulting in drastic changes in the level populations of (1,1) sub-states. Expansion (contraction) is found to strengthen the inner as well as outer satellite lines on the red (blue) side, while suppressing those on the other side. The line anomaly becomes prominent as the ammonia column density increases. It is concluded that the hyperfine line intensity ratios could be a good probe for tracing the systematic motion inside the dense cores without relying on detailed analysis of line shapes.

Aims. We aim at deriving the excitation conditions of the interstellar gas as well as the local FUV intensities in the molecular cloud surrounding NGC 3603 to get a coherent picture of how the gas is energized by the central stars. Methods. The NANTEN2-4 m submillimeter antenna is used to map the [CI] 1-0, 2-1 and CO 4-3, 7-6 lines in a 2 × 2 region around the young OB cluster NGC 3603 YC. These data are combined with C 18 O 2-1 data, HIRES-processed IRAS 60 μm and 100 μm maps of the FIR continuum, and Spitzer/IRAC maps. Results. The NANTEN2 observations show the presence of two molecular clumps located south-east and south-west of the cluster and confirm the overall structure already found by previous CS and C 18 O observations. We find a slight position offset of the peak intensity of CO and [CI], and the atomic carbon appears to be further extended compared to the molecular material. We used the HIRES farinfrared dust data to derive a map of the FUV field heating the dust. We constrain the FUV field to values of χ = 3−6 × 10 3 in units of the Draine field across the clouds. Approximately 0.2 to 0.3% of the total FUV energy is re-emitted in the [CII] 158 μm cooling line observed by ISO. Applying LTE and escape probability calculations, we derive temperatures (T MM1 = 43 K, T MM2 = 47 K), column densities (N MM1 = 0.9 × 10 22 cm −2 , N MM2 = 2.5 × 10 22 cm −2 ) and densities (n MM1 = 3 × 10 3 cm −3 , n MM2 = 10 3 −10 4 cm −3 ) for the two observed molecular clumps MM1 and MM2. Conclusions. The cluster is strongly interacting with the ambient molecular cloud, governing its structure and physical conditions. A stability analysis shows the existence of gravitationally collapsing gas clumps which should lead to star formation. Embedded IR sources have already been observed in the outskirts of the molecular cloud and seem to support our conclusions.

Context. Studying molecular gas in the central regions of the star burst galaxies NGC 4945 and Circinus enables us to characterize the physical conditions and compare them to previous local and high-z studies. Aims. We estimate temperature, molecular density and column densities of CO and atomic carbon. Using model predictions we give a range of estimated CO/C abundance ratios. Methods. Using the new NANTEN2 4 m sub-millimeter telescope in Pampa La Bola, Chile, we observed for the first time CO 4-3 and [C i] 3 P 1 − 3 P 0 at the centers of both galaxies at linear scale of 682 pc and 732 pc respectively. We compute the cooling curves of 12 CO and 13 CO using radiative transfer models and estimate the physical conditions of CO and [CI].Results. 3 P 1 − 3 P 0 /CO 4-3 ratio of integrated intensities are large at 1.2 in NGC 4945 and 2.8 in Circinus. Combining previous CO J = 1−0, 2-1 and 3-2 and 13 CO J = 1−0, 2-1 studies with our new observations, the radiative transfer calculations give a range of densities, n(H 2 ) = 10 3 −3 × 10 4 cm −3 , and a wide range of kinetic temperatures, T kin = 20−100 K, depending on the density. To discuss the degeneracy in density and temperature, we study two representative solutions. In both galaxies the estimated total [CI] cooling intensity is stronger by factors of ∼1−3 compared to the total CO cooling intensity. The CO/C abundance ratios are 0.2−2, similar to values found in Galactic translucent clouds. Conclusions. Our new observations enable us to further constrain the excitation conditions and estimate the line emission of higher-J CO-and the upper [CI]-lines. For the first time we give estimates for the CO/C abundance ratio in the center regions of these galaxies. Future CO J = 7−6 and [CI] 2-1 observations will be important to resolve the ambiguity in the physical conditions and confirm the model predictions.

[1] In a new Tatiana-2 mission the measurement of transient luminous events (TLE) in the Earth atmosphere in nadir direction are planned. Near UV temporal images of TLE in millisecond scale will be measured together with temporal profiles in 8 channels of wide spectrum of TLE emission. Simultaneously temporal variation of electron flux at the satellite orbit will be measured. Aims of these measurements are to continue research of bright UV flashes, started in the Tatiana-1 mission (Universitetsky-Tatiana satellite), their global distribution, their rate over oceans and continents, and their possible correlation with lunar phase. Special attention will be paid to search for correlation between UV flashes from the atmosphere and variations of electron flux in the atmospheremagnetosphere system.