Aims. We present Herschel-HIFI observations of 14 water lines in W43-MM1, a massive protostellar object in the luminous starcluster-forming region W43. We place our study in the more general context of high-mass star formation. The dynamics of these regions may be represented by either the monolithic collapse of a turbulent core, or competitive accretion. Water turns out to be a particularly good tracer of the structure and kinematics of the inner regions, allowing an improved description of the physical structure of the massive protostar W43-MM1 and an estimation of the amount of water around it. Methods. We analyze the gas dynamics from the line profiles using Herschel-HIFI observations acquired as part of the Water In Star-forming regions with Herschel project of 14 far-IR water lines (H 16 2 O, H 17 2 O, H 18 2 O), CS(11-10), and C 18 O(9-8) lines, using our modeling of the continuum spectral energy distribution. The spectral modeling tools allow us to estimate outflow, infall, and turbulent velocities and molecular abundances. We compare our results to previous studies of low-, intermediate-, and other high-mass objects. Results. As for lower-mass protostellar objects, the molecular line profiles are a mix of emission and absorption, and can be decomposed into "medium" (full width at half maximum FWHM 5-10 km s −1 ), and "broad" velocity components (FWHM 20-35 km s −1 ). The broad component is the outflow associated with protostars of all masses. Our modeling shows that the remainder of the water profiles can be well-fitted by an infalling and passively heated envelope, with highly supersonic turbulence varying from 2.2 km s −1 in the inner region to 3.5 km s −1 in the outer envelope. In addition, W43-MM1 has a high accretion rate of between 4.0 × 10 −4 and 4.0 × 10 −2 M yr −1 , as derived from the fast (0.4-2.9 km s −1 ) infall observed. We estimate a lower mass limit for gaseous water of 0.11 M and total water luminosity of 1.5 L (in the 14 lines presented here). The central hot core is detected with a water abundance of 1.4 × 10 −4 , while the water abundance for the outer envelope is 8 × 10 −8 . The latter value is higher than in other sources, and most likely related to the high turbulence and the micro-shocks created by its dissipation. Conclusions. Examining the water lines of various energies, we find that the turbulent velocity increases with the distance from the center. While not in clear disagreement with the competitive accretion scenario, this behavior is predicted by the turbulent core model. Moreover, the estimated accretion rate is high enough to overcome the expected radiation pressure.

Abstract. We report observations made with the IRAM 30 m radiotelescope in the HCN(1-0) and HCO + (1-0) lines towards a sample of molecular complexes (GMCs) in the disk of the Andromeda galaxy (M 31). The targets were identified bright CO GMCs selected from the IRAM 30 m CO survey with various morphologies and environments. The clouds vary in galactocentric distances from 2.4 to 15.5 kpc. The HCN and HCO + emission is easily detected in almost all observed positions, with line widths generally similar to the CO ones and there is a good correlation between the two dense gas tracers. The HCO + emission is slightly stronger than the HCN, in particular towards GMCs with a strong star formation activity. However the HCO + emission is weaker than the HCN towards a quiescent cloud in the inner part of M 31, which could be due to a lower abundance of HCO + . We derive I HCN /I CO ratios between 0.008 and 0.03 and I HCO + /I CO ratios between less than 0.003 and 0.04. We study the radial distribution of the dense gas in the disk of M 31. Unlike our Galaxy the HCO + /CO ratio is lower in the center of M 31 than in the arms, which can be explained by both a lower abundance of HCO + and different conditions of excitation. Furthermore the HCN/CO and HCO + /CO ratios appear to be higher in the inner spiral arm and weaker in the outer arm.

High resolution line spectra of star-forming regions are mines of information: they provide unique clues to reconstruct the chemical, dynamical, and physical structure of the observed source. We present the first results from the Herschel key project "Chemical HErschel Surveys of Star forming regions", CHESS. We report and discuss observations towards five CHESS targets, one outflow shock spot and four protostars with luminosities bewteen 20 and 2 × 10 5 L : L1157-B1, IRAS 16293-2422, OMC2-FIR4, AFGL 2591, and NGC 6334I. The observations were obtained with the heterodyne spectrometer HIFI on board Herschel, with a spectral resolution of 1 MHz. They cover the frequency range 555−636 GHz, a range largely unexplored before the launch of the Herschel satellite. A comparison of the five spectra highlights spectacular differences in the five sources, for example in the density of methanol lines, or the presence/absence of lines from S-bearing molecules or deuterated species. We discuss how these differences can be attributed to the different star-forming mass or evolutionary status.