We probe the spatial distribution of the [C ii] μm fine-structure emission and its association with neutral and molecular gas in a 5′.7 × 3′.7 (∼3.3 × 2.1 pc2) region of the M17 SW nebula. Comparison of velocity-resolved [C ii] emission maps with other atomic and molecular tracers is possible for the first time with the dual band receiver GREAT on board the SOFIA airborne telescope. We detected [C ii] emission in a much broader velocity range than the CO-lines (Pérez-Beaupuits et al. 2012). Only [C ii] narrow channel maps at intermediate velocities (between 10 and 24 kms) show correlations with other molecular gas components, supporting a clumpy cloud scenario. At lower (< 10 kms) and higher (>24 kms) velocities instead, we see more than 60% of the region mapped in [C ii] that is not associated with other tracers of star-forming material, the so called “CO-dark” gas. Interaction with winds and outflows lead to substantial excitation of [C ii] emitting gas, so that ablation and shock-interaction have to be taken into account to model the observed [C ii] emission.

An overview is given of the capabilities of the HIFI instrument on board of the Herschel Space Observatory, its observing modes and its calibration. With the superb spectral resolution and wide frequency coverage of HIFI a plethora of astrophysical studies are done.

Within the Herschel key project “The Warm And Dense ISM” (WADI) we systematically observe a number of prominent photon-dominated regions (PDRs) to measure the impact of varying UV fields on the energy balance, the chemical and dynamical structure of heated molecular clouds.

The ESA Herschel Space Observatory was successfully launched on 14 May 2009, and is currently operating in its routine science phase. Due to the rapidly evolving nature of the mission at this point a short summary with pointers to more up-to-date additional information is provided here.

Here we present the results of a 3 mm survey of 23 galaxies, obtained with the EMIR receiver at the IRAM 30 m telescope. Emission of the main molecular species is compared with existing chemical models, in order to find and test molecular signatures of galaxy evolution and to compare them to IR evolutionary tracers.

Over the past 3 years, we have conducted a survey of 100 square degrees of the southern Galactic plane with the Mopra radiotelescope (HOPS). The survey includes observations of multiple spectral lines in the 12 mm band, with the most important being the water maser transition at 22.2 GHz and the non-metastable inversion transitions of ammonia. We report on initial results from HOPS, including the detection of 540 water masers, about two-thirds of which appear to be new detections. We also find widespread emission in the NH3 (1,1) line, as well as detec tions in the NH3 (2,2), (3,3), (6,6) and (9,9) lines.

The paper focuses on collisional excitation rates of molecules by He, H2 and electrons relevant to the interstellar medium, it discusses currently available data, presents very recent work and outlines new work being carried out in order to provide easy access to these molecular data. In particular outlines of the latest developments in the BASECOL database and of the “Virtual Molecular Data Centre” capabilities are provided.

We present the initial results of a spectral line survey of L1157 B1 with the Nobeyama 45 m telescope. So far, we have covered the frequencey range of 13.7 GHz (82.0–94.5 GHz and 96.3–97.5 GHz), and have detected 22 species including CH3CHO, HCOOH, HCOOCH3, HNCO, NH2CHO, CH3CN, and CCS. We have also detected the line of CH2DOH. These results demonstrate rich chemistry in this shocked region, which would mainly originate from evaporation of ice mantles by means of shocks.

In the Magellanic Clouds, the [CII]/CO and the [CII]/FIR ratios are much higher than seen in Milky Way star-forming regions. The enhanced relative strength of the [CII] line reflects the physical environment characterised by the low metallicities, dust abundances, and PAH abundances of the LMC, and especially the SMC.

We present new, wide, and deep images in the AzTEC/ASTE 1.1 mm continuum and the 12 CO (J = 1–0) emission toward the northern part of the Orion-A GMC. We have found evidence for interactions between molecular clouds and the external forces that may trigger star formation. Two types of possible triggers were revealed: (1) Collisions of the diffuse gas on the cloud surface, particularly at the eastern side of the OMC-2/3 region, and (2) Irradiation of UV on the pre-existing filaments and dense molecular cloud cores. Our wide-field and high-sensitivity imaging has provided the first comprehensive view of the potential sites of triggered star formation in the Orion-A GMC.

The Herschel HIFI Key Program, Galactic Observations of Terahertz C+ (GOT C+) is a survey of [CII] 1.9 THz emission throughout the Galaxy. Comparison of the first results of this survey with HI and CO isotopomer emission reveals excess [CII] emission beyond that expected from HI and CO layers alone, and is best explained as coming from a hidden layer of H2 gas, the so-called ISM “dark gas”.

We present results of a 1.1 mm deep survey of the AKARI Deep Field South (ADF-S) with AzTEC mounted on the Atacama Submillimetre Telescope Experiment (ASTE). We obtained a map of 0.25 deg2 area with an rms noise level of 0.32–0.71 mJy. This is one of the deepest and widest maps thus far at millimetre and submillimetre wavelengths. We uncovered 198 sources with a significance of 3.5–15.6σ, providing the largest catalog of 1.1 mm sources in a contiguous region. Most of the sources are not detected in the far-infrared bands of the AKARI satellite, suggesting that they are mostly at z ≥ 1.5 given the detection limits. We construct differential and cumulative number counts of the ADF-S, the Subaru/XMM Newton Deep Field (SXDF), and the SSA 22 field surveyed by AzTEC/ASTE, which provide currently the tightest constraints on the faint end. The integration of the differential number counts of the ADF-S find that the contribution of 1.1 mm sources with  ≥1 mJy to the cosmic infrared background (CIB) at 1.1 mm is 12–16%, suggesting that the large fraction of the CIB originates from faint sources of which number counts are not yet constrained. We estimate the cosmic star-formation rate density contributed by 1.1 mm sources with  ≥1 mJy using the differential number counts and find that it is lower by about a factor of 5–10 compared to those derived from UV/optically-selected galaxies at z ~ 2–3. Clustering analyses of AzTEC sources in the ADF-S and the SXDF find that bright (>3 mJy) AzTEC sources are more strongly clustered than faint (< 3 mJy) AzTEC sources and the average mass of dark halos hosting bright AzTEC sources was calculated to be 1013–1014M⊙. Comparison of correlation length of AzTEC sources with other populations and with a bias evolution model suggests that dark halos hosting bright AzTEC sources evolve into systems of clusters at present universe and the AzTEC sources residing the dark halos evolve into massive elliptical galaxies located in the center of clusters.

We use the DustEM model coupled with a radiative transfer code to fit the Herschel and Spitzer emission of the Orion Bar. The thermal dust emission at the 250-μm peak position is well reproduced but we overestimate the stochastically heated grain emission. The dust model parameters are checked with the Meudon PDR code and are consistent with the spectroscopic data from the SPIRE FTS.

Deep far-infrared photometric surveys studying galaxy evolution and the nature of the cosmic infrared background are a key strength of the Herschel mission. The PACS Evolutionary Probe (PEP) guaranteed time key program obtains deep photometric surveys of some of the key extragalactic multiwavelength fields at wavelengths between 70 and 160 μm. This contribution gives an overview of first science results, illustrating the potential of Herschel in providing calorimetric star formation rates for various high redshift galaxy populations, thus testing and superseding previous extrapolations from other wavelengths, and enabling a wide range of galaxy evolution studies.

New images of the interstellar medium provided by Herschel and Planck bring spectacular evidence of the intricate and filamentary structure of the interstellar medium, betraying its turbulent nature. Although turbulence is a subject of interest in astronomy, little is know about the origin of turbulence in the interstellar medium. We suggest that part of the turbulence in the Orion molecular cloud be due to the decay of the Kelvin-Helmholtz instability.

The dynamics of stars and gas appear markedly different in flocculent, tidally induced and quasi-stationary spiral galaxies. Numerical simulations show that the gas and stars exhibit fairly chaotic dynamics during a tidal interaction, unlike the predictions of density wave theory. For a flocculent galaxy, the stars and gas tend to be situated in potential minima associated with the stellar distribution. I will demonstrate a possible observational test to distinguish between drivers of spiral structure by comparing the ages of stellar clusters, using the results of the simulations as an example.

With high resolution simulations, we are also starting to resolve giant molecular clouds, and can thus relate the properties of these clouds to the presence of spiral structure. Calculations so far suggest that spiral structure simply defines where the clouds form, rather than directly triggering star formation. In the last section of this review, I highlight recent efforts to produce synthetic HI and CO observations from numerical simulations.

We have found low-mass star-forming regions with extremely high abundances of carbon-chain molecules. Those are L1527 in Taurus and IRAS 15398-3359 in Lupus. In these sources, carbon-chain molecules would be regenerated in a lukewarm region near the protostar, triggered by the evaporation of the CH4 ice. This is new carbon-chain chemistry (Warm Carbon-Chain Chemistry: WCCC) in contrast to the conventional one applied to cold starless cores. Our interferometric observation shows a steep abundance increase of the carbon-chain molecules inward of a radius of 500 − 1000 AU from the protostar. This size corresponds to the temperature range of 20–30 K, which is close to the evaporation temperature of CH4 (25 K). This result is therefore consistent with the WCCC. The discovery of the WCCC sources demonstrates chemical diversity of low-mass star-forming regions. In particular, a remarkable contrast can be seen between the WCCC and the hot corino chemistry known in IRAS 16293-2422. A possible origin for the diversity would be the time scale of the starless-core phase; a shorter contraction time would result in the WCCC. Relatively low deuterium fractionation ratios in L1527 also support this scenario. If so, chemical compositions will tell us an important clue to understand the source-to-source variation of star-formation processes.

In this brief review we discuss how some of our basic understanding of chemical processes in interstellar medium has received a boost from the Herschel Space Observatory. With Herschel in operations for over 1 year, it is still early to discuss the full impact of new results and instead I demonstrate the new science enabled by near-complete spectroscopic access to sub-millimeter to far-infrared wavelengths.

Dust grains are an important component of star forming regions and are therefore a powerful tracer of the location and mass of prestellar cores. However, the properties of dust grains in such dense regions are poorly constrained, causing difficulties in the modeling of the physical properties of dense cores. One of the fundamental properties of dust grains is their size distribution, which is relatively well-known in the diffuse ISM but not very well constrained in dense regions. Indirect evidence is consistent with the presence of large grains; however, to date, interpreting submm emission measurements or absorption in the near-infrared (NIR)/mid-infrared (MIR) domains is difficult due to the ambiguity between density (and temperature if in emission) variations and grain properties. Recently, we have discovered emission at 3.6 and 4.5 μm towards the densest parts of L183. We have named this effect coreshine, by analogy with the cloudshine, seen at the surface of dark clouds in the near-infrared. This 3.6 and 4.5 μm emission can only be explained by the strong scattering of background interstellar radiation due to micron-size grains and show that the average grain size increase needs to be proportional to the cloud core density gradient to reproduce the observations. We show that the scattering effect is very sensitive to the grain size distribution; therefore these observations will provide a new tool with which to study grain properties. In a subsequent search through about a hundred of dense low mass core regions in the Spitzer Heritage Archive, we find that the effect is present in  ~50% of the sources, including prestellar cores, Class 0 and I sources with or without outflow, showing that the coreshine effect should rapidly become a general observational method to investigate dark cloud and grain properties.