Water and acetaldehyde in HH212: The first hot corino in Orion

Abstract

Aims. Using the unprecedented combination of high resolution and sensitivity offered by ALMA, we aim to investigate whether and how hot corinos, circumstellar disks, and ejected gas are related in young solar-mass protostars. Methods. We observed CH3CHO and deuterated water (HDO) high-excitation (Eu up to 335 K) lines towards the Sun-like protostar HH212-MM1. Results. For the first time, we have obtained images of CH3CHO and HDO emission in the inner 100 AU of HH212. The multifrequency line analysis allows us to contrain the density (>107 cm-3), temperature (100 K), and CH3CHO abundance (0.2-2 × 10-9) of the emitting region. The HDO profile is asymmetric at low velocities (≤2 kms-1 from Vsys). If the HDO line is optically thick, this points to an extremely small (∼20-40 AU) and dense (>109 cm-3) emitting region. Conclusions. We report the first detection of a hot corino in Orion. The HDO asymmetric profile indicates a contribution of outflowing gas from the compact central region, possibly associated with a dense disk wind.