Context. On the basis of its low luminosity, its chemical composition, and the absence of a large-scale outflow, the dense core Cha-MMS1 located in the Chamaeleon I molecular cloud was proposed as a first hydrostatic core (FHSC) candidate a decade ago. Aims. Our goal is to test this hypothesis by searching for a slow, compact outflow driven by Cha-MMS1 that would match the predictions of MHD simulations for this short phase of star formation. Methods. We use the Atacama Large Millimetre/submillimetre Array (ALMA) to map Cha-MMS1 at high angular resolution in CO 3-2 and 13 CO 3-2 as well as in continuum emission. Results. We report the detection of a bipolar outflow emanating from the central core, along a (projected) direction roughly parallel to the filament in which Cha-MMS1 is embedded and perpendicular to the large-scale magnetic field. The morphology of the outflow indicates that its axis lies close to the plane of the sky. We measure velocities corrected for inclination of more than 90 km s −1 which is clearly incompatible with the expected properties of a FHSC outflow. Several properties of the outflow are determined and compared to previous studies of Class 0 and Class I protostars. The outflow of Cha-MMS1 has a much smaller momentum force than the outflows of other Class 0 protostars. In addition, we find a dynamical age of 200-3000 yr indicating that Cha-MMS1 might be one of the youngest ever observed Class 0 protostars. While the existence of the outflow suggests the presence of a disk, no disk is detected in continuum emission and we derive an upper limit of 55 au to its radius. Conclusions. We conclude that Cha-MMS1 has already gone through the FHSC phase and is a young Class 0 protostar, but it has not brought its outflow to full power yet.

Context. The 1 • .3 (G1.3) and 1 • .6 (G1.6) cloud complexes in the central molecular zone (CMZ) of our Galaxy have been proposed to possibly reside at the intersection region of the X1 and X2 orbits for several reasons. This includes the detection of co-spatial low-and high-velocity clouds, high velocity dispersion, high fractional molecular abundances of shock-tracing molecules, and kinetic temperatures that are higher than for usual CMZ clouds. Aims. By investigating the morphology and deriving physical properties as well as chemical composition, we want to find the origin of the turbulent gas and, in particular, whether evidence of an interaction between clouds can be identified. Methods. We mapped both cloud complexes in molecular lines in the frequency range from 85 to 117 GHz with the IRAM 30 m telescope. The APEX 12 m telescope was used to observe higher frequency transitions between 210 and 475 GHz from selected molecules that are emitted from higher energy levels. We performed non-local thermodynamic equilibrium (non-LTE) modelling of the emission of an ensemble of CH 3 CN lines to derive kinetic temperatures and H 2 volume densities. These were used as starting points for non-LTE modelling of other molecules, for which column densities and abundances were determined and compared with values found for other sources in the CMZ.Results. The kinematic structure of G1.3 reveals an 'emission bridge' at intermediate velocities (∼150 km s −1 ) connecting lowvelocity (∼100 km s −1 ) and high-velocity (∼180 km s −1 ) gas and an overall fluffy shell-like structure. These may represent observational evidence of cloud-cloud interactions. Low-and high-velocity gas components in G1.6 do not show this type of evidence of an interaction, suggesting that they are spatially separated. We selected three positions in each cloud complex for further analysis. Each position reveals several gas components at various peak velocities and of various line widths. We derived kinetic temperatures of 60-100 K and H 2 volume densities of 10 4 -10 5 cm −3 in both complexes. Molecular abundances relative to H 2 suggest a similar chemistry of the two clouds, which is moreover similar to that of other GC clouds and, especially, agrees well with that of G+0.693 and G−0.11. Conclusions. We conclude that G1.3 may indeed exhibit signs of cloud-cloud interactions. In particular, we propose an interaction of gas that is accreted from the near-side dust lane to the CMZ, with gas pre-existing at this location. Low-and high-velocity components in G1.6 are rather coincidentally observed along the same line of sight. They may be associated with either overshot decelerated gas from the far-side dust line or actual CMZ gas and high-velocity gas moving on a dust lane. These scenarios would be in agreement with numerical simulations.

Context. The presence of many interstellar complex organic molecules (COMs) in the gas phase in the vicinity of protostars has long been associated with their formation on icy dust grain surfaces before the onset of protostellar activity, and their subsequent thermal co-desorption with water, the main constituent of the grains' ice mantles, as the protostar heats its environment to ∼100 K. Aims. Using the high angular resolution provided by the Atacama Large Millimetre/submillimetre Array (ALMA) we want to resolve the COM emission in the hot molecular core Sagittarius B2 (N1) and thereby shed light on the desorption process of COMs in hot cores. Methods. We use data taken as part of the 3 mm spectral line survey Re-exploring Molecular Complexity with ALMA (ReMoCA) to investigate the morphology of COM emission in Sagittarius B2 (N1). We also use ALMA continuum data at 1 mm taken from the literature. Spectra of ten COMs (including one isotopologue) are modelled under the assumption of Local Thermodynamic Equilibrium (LTE) and population diagrams are created for these COMs for positions at various distances to the south and west from the continuum peak. Based on this analysis, we produce resolved COM rotation temperature and column density profiles. H 2 column density profiles are derived from dust continuum emission and C 18 O 1-0 emission and used to derive COM abundance profiles as a function of distance and temperature. These profiles are compared to astrochemical models. Results. Based on the morphology, a rough separation into O-and N-bearing COMs can be done. The temperature profiles span a range of 80-300 K with power-law indices from −0.4 to −0.8, in agreement with expectations of protostellar heating of an envelope with optically thick dust. Column density and abundance profiles reflect a similar trend as seen in the morphology. While abundances of N-bearing COMs peak only at highest temperatures, those of most O-bearing COMs peak at lower temperatures and remain constant or decrease towards higher temperatures. Many abundance profiles show a steep increase at ∼100 K. To a great extent, the observed results agree with results of astrochemical models that, besides the co-desorption with water, predict that O-bearing COMs are mainly formed on dust grain surfaces at low temperatures while at least some N-bearing COMs and CH 3 CHO are substantially formed in the gas phase at higher temperatures. Conclusions. Our observational results, in comparison with model predictions, suggest that COMs that are exclusively or to a great extent formed on dust grains desorb thermally at ∼100 K from the grain surface likely alongside water. A dependence on the COM binding energy is not evident from our observations. Non-zero abundance values below ∼100 K suggest that another desorption process of COMs is at work at these low temperatures: either non-thermal desorption or partial thermal desorption related to the lower binding energies experienced by COMs in the outer, water-poor ice layers. In either case, this is the first t...