Space Infrared Telescope for Cosmology and Astrophysics (SPICA), the cryogenic infrared space telescope recently pre-selected for a ‘Phase A’ concept study as one of the three remaining candidates for European Space Agency (ESA's) fifth medium class (M5) mission, is foreseen to include a far-infrared polarimetric imager [SPICA-POL, now called B-fields with BOlometers and Polarizers (B-BOP)], which would offer a unique opportunity to resolve major issues in our understanding of the nearby, cold magnetised Universe. This paper presents an overview of the main science drivers for B-BOP, including high dynamic range polarimetric imaging of the cold interstellar medium (ISM) in both our Milky Way and nearby galaxies. Thanks to a cooled telescope, B-BOP will deliver wide-field 100–350 $\mu$m images of linearly polarised dust emission in Stokes Q and U with a resolution, signal-to-noise ratio, and both intensity and spatial dynamic ranges comparable to those achieved by Herschel images of the cold ISM in total intensity (Stokes I). The B-BOP 200 $\mu$m images will also have a factor $\sim $30 higher resolution than Planck polarisation data. This will make B-BOP a unique tool for characterising the statistical properties of the magnetised ISM and probing the role of magnetic fields in the formation and evolution of the interstellar web of dusty molecular filaments giving birth to most stars in our Galaxy. B-BOP will also be a powerful instrument for studying the magnetism of nearby galaxies and testing Galactic dynamo models, constraining the physics of dust grain alignment, informing the problem of the interaction of cosmic rays with molecular clouds, tracing magnetic fields in the inner layers of protoplanetary disks, and monitoring accretion bursts in embedded protostars.

The SPICA mid- and far-infrared telescope will address fundamental issues in our understanding of star formation and ISM physics in galaxies. A particular hallmark of SPICA is the outstanding sensitivity enabled by the cold telescope, optimised detectors, and wide instantaneous bandwidth throughout the mid- and far-infrared. The spectroscopic, imaging, and polarimetric observations that SPICA will be able to collect will help in clarifying the complex physical mechanisms which underlie the baryon cycle of galaxies. In particular, (i) the access to a large suite of atomic and ionic fine-structure lines for large samples of galaxies will shed light on the origin of the observed spread in star-formation rates within and between galaxies, (ii) observations of HD rotational lines (out to ~10 Mpc) and fine structure lines such as [C ii] 158 μm (out to ~100 Mpc) will clarify the main reservoirs of interstellar matter in galaxies, including phases where CO does not emit, (iii) far-infrared spectroscopy of dust and ice features will address uncertainties in the mass and composition of dust in galaxies, and the contributions of supernovae to the interstellar dust budget will be quantified by photometry and monitoring of supernova remnants in nearby galaxies, (iv) observations of far-infrared cooling lines such as [O i] 63 μm from star-forming molecular clouds in our Galaxy will evaluate the importance of shocks to dissipate turbulent energy. The paper concludes with requirements for the telescope and instruments, and recommendations for the observing strategy.

We present a case study of a single high-mass protostar associated with an infrared quiet massive clump selected from the ATLASGAL survey. The thermal dust emission reveals a single collapsing object associated with a prominent molecular outflow. We detect bright emission from a torsionally excited state transition of CH3OH offset from the protostar that is well explained by shocks at the transition from the infalling envelope onto an accretion disk.

The Millimetre Astronomy Legacy Team 90 GHz (MALT90) survey aims to characterise the physical and chemical evolution of high-mass star-forming clumps. Exploiting the unique broad frequency range and on-the-fly mapping capabilities of the Australia Telescope National Facility Mopra 22 m single-dish telescope1, MALT90 has obtained 3′ × 3′ maps towards ~2 000 dense molecular clumps identified in the ATLASGAL 870 μm Galactic plane survey. The clumps were selected to host the early stages of high-mass star formation and to span the complete range in their evolutionary states (from prestellar, to protostellar, and on to $\mathrm{H\,{\scriptstyle {II}}}$ regions and photodissociation regions). Because MALT90 mapped 16 lines simultaneously with excellent spatial (38 arcsec) and spectral (0.11 km s−1) resolution, the data reveal a wealth of information about the clumps’ morphologies, chemistry, and kinematics. In this paper we outline the survey strategy, observing mode, data reduction procedure, and highlight some early science results. All MALT90 raw and processed data products are available to the community. With its unprecedented large sample of clumps, MALT90 is the largest survey of its type ever conducted and an excellent resource for identifying interesting candidates for high-resolution studies with ALMA.

Submillimeter dust continuum emission traces high molecular column densities and, thus, dense cloud regions in which new stars are forming. Surveys of the Galactic plane in such emission have the potential of delivering an unbiased view of high-mass star formation throughout the Milky Way. The location of the APEX telescope on the Chajnantor plateau in Chile is ideally suited for mapping the inner Galaxy. ATLASGAL, The APEX Telescope Large Area Survey of the Galaxy at 870 μm, is a survey of the Galactic plane using the Large APEX Bolometer Camera (LABOCA), in the Galactic longitude and latitude ranges of  ±60 and  ±1.5°, respectively. This survey is providing an unbiased sample of cold dusty clumps in the Galaxy at submillimeter wavelength and a variety of molecular line follow-up observations have been started to characterize the physical and chemical conditions in the newly found clumps. Here, first results from this survey and its follow-up programs are described.

The understanding of the star formation is still on progress. Especially, the formation of high-mass stars is much less understood than the low-mass case. Water, one of the most important molecules in the Universe, might elucidate key episodes in the process of stellar birth, and especially could be a major role in the formation of high-mass stars. We present here the first results of the WISH program, dedicated to the water study in star-forming regions with Herschel, concerning the massive star-forming regions.

The Rosette molecular cloud has a characteristic morphology, where the central OB cluster NGC 2244 has blown a circular-shaped cavity into the cloud and the expanding HII-region now interacts with the cloud. We use continuum data obtained with the PACS (70 and 160 μm) and SPIRE instruments (250, 350, 500 μm) of the Herschel telescope to investigate the spatial distribution of cold and warm gas and to locate all star-forming sites in Rosette. We detected a clear negative temperature gradient and a positive density gradient (running from the HII-region/molecular cloud interface into the cloud), and an age-sequence (from more evolved to younger) with increasing distance to the cluster NGC 2244. The existence of such temperature and density gradients and the observed age-sequence imply that star formation in Rosette may indeed be influenced by the radiative impact of the central NGC 2244 cluster.

A systematic, high angular-resolution study of IR-quiet Massive Dense Cores (MDCs) of Cygnus-X in continuum and high-density molecular tracers is presented. The results are compared with the quasi-static and the dynamical evolutionary scenario. We find that the fragmentation properties are not compatible with the quasi-static, monolithic collapse scenario, nor are they entirely compatible with the formation of a cluster of mostly low-mass stars. The kinematics of MDCs shows individual velocity components appearing as coherent flows, which indicate important dynamical processes at the scale of the mass reservoir around high-mass protostars.

Submillimeter continuum emission traces high molecular column densities and, thus, dense cloud regions in which new stars are forming. Surveys of the Galactic plane in such emission have the potential of delivering an unbiased view of high-mass star formation throughout the Milky Way. Here we present the scope, current status and first results of ATLASGAL, an ongoing survey of the Galactic plane using the Large APEX Bolometer Camera (LABOCA) on the Atacama Pathfinder Experiment (APEX) telescope at the Chajnantor plateau in Chile. Aimed at mapping 360 square degrees at 870 μm, with a uniform sensitivity of 50 mJy/beam, this survey will provide the first unbiased sample of cold dusty clumps in the Galaxy at submillimeter wavelengths. These will be targets for molecular line follow-up observations and high resolution studies with ALMA and the EVLA.

We started (sub-)millimeter continuum and line studies of entire molecular cloud complexes located at intermediate distances from the Sun (1–3 kpc). Such an unbiased approach allows to identify and characterize the earliest phases of high-mass stars overlooked by IRAS or MSX. Our complete MAMBO-2 surveys of the Cygnus X and NGC 7538 complexes reveal a large population of ${\sim} 0.1$ pc-size massive young stellar objects (MYSOs) harboring high-mass infrared-quiet protostars. The determination of the nature of all the new millimeter sources is still in progress but we have already collected evidence that the infrared-quiet (or class 0-like) protostellar phase might last as long as the better-known infrared-bright protostellar phase. Besides, our complete census of MYSOs fails to discover the high-mass analogues of pre-stellar dense cores. We propose that the observed lower-density pre-stellar clumps (${>} 1$ pc) rapidly concentrate and collapse as also found in the kinematical studies of other prominent clumps. Indeed, CS and HCO$^+$ mappings in W43 and Cygnus X suggest global supersonic contraction with inward velocities of several km s−1 on parsec scales. Our work and similar studies of entire star-forming complexes will thus definitively contribute to a better knowledge of the earliest phases of high-mass star formation.

We present ISOCAM observations (5-18 μm) of illuminated surfaces of molecular clouds. The emission properties of the transiently heated small particles, which dominate the emission observed by ISOCAM, are analysed in relation with the spatial structure of the material. Striking spatial variations of the infrared colour (5-8.5 μm/12-18 μm) are detected. Spectroscopic observations show that they are due to variations of the intensity of the aromatic features (especially at 7.7 μm) relatively to the continuum emission increasing towards long wavelengths. Compared to the intensity of the continuum emission, the intensity of the aromatic features are significantly fainter at the illuminated surfaces of dense structures than in low density regions surrounding these dense structures. This effect could be the signature of photo-chemical evolution, size segregation due to grain dynamics in uni-directional radiation fields, or abundance variations of very small particles.