Outflows from the youngest stars are mostly molecular.

The formation of stars and planets is accompanied not only by the build-up of matter, namely accretion, but also by its expulsion in the form of highly supersonic jets that can stretch for several parsecs. As accretion and jet activity are correlated and because young stars acquire most of their mass rapidly early on, the most powerful jets are associated with the youngest protostars. This period, however, coincides with the time when the protostar and its surroundings are hidden behind many magnitudes of visual extinction.

ALMA Compact Array observations of the Fried Egg nebula: Evidence for large-scale asymmetric mass-loss from the yellow hypergiant IRAS 17163-3907.

Yellow hypergiants are rare and represent a fast evolutionary stage of massive evolved stars. That evolutionary phase is characterised by a very intense mass loss, the understanding of which is still very limited. Here we report ALMA Compact Array observations of a 50″-mosaic toward the Fried Egg nebula, around one of the few Galactic yellow hypergiants IRAS 17163-3907.

/HIFI observations of the circumstellar ammonia lines in IRC+10216.

Context: A discrepancy exists between the abundance of ammonia (NH) derived previously for the circumstellar envelope (CSE) of IRC+10216 from far-IR submillimeter rotational lines and that inferred from radio inversion or mid-infrared (MIR) absorption transitions.

Aims: To address the discrepancy described above, new high-resolution far-infrared (FIR) observations of both ortho- and para-NH transitions toward IRC+10216 were obtained with , with the goal of determining the ammonia abundance and constraining the distribution of NH in the envelope of IRC+10216.

Methods: We used the Heterodyne Instrument for the Far Infrared (HIFI) on board to observe all rotational transitions up to the = 3 level (three ortho- and six para-NH lines).