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Article Dans Une Revue Astronomy and Astrophysics - A&A Année : 2014

The ALMA view of the protostellar system HH212

Résumé

Context. Because it is viewed simply edge-on, the HH212 protostellar system is an ideal laboratory for studying the interplay of infall, outflow, and rotation in the earliest stages of low-mass star formation.
Aims: We wish to exploit the unmatched combination of high angular resolution, high sensitivity, high-imaging fidelity, and spectral coverage provided by ALMA to shed light on the complex kinematics of the innermost central regions of HH212.
Methods: We mapped the inner 10" (4500 AU) of the HH212 system at ~=0.5" resolution in several molecular tracers and in the 850 mum dust continuum using the ALMA interferometer in band 7 in the extended configuration of the Early Science Cycle 0 operations.
Results: Within a single ALMA spectral set-up, we simultaneously identify all the crucial ingredients known to be involved in the star formation recipe: (i) the fast, collimated bipolar SiO jet driven by the protostar; (ii) the large-scale swept-up CO outflow; (iii) the flattened rotating and infalling envelope, with bipolar cavities carved by the outflow (in C17O(3-2)); and (iv) a rotating wide-angle flow that fills the cavities and surrounds the axial jet (in C34S(7-6)). In addition, the compact high-velocity C17O emission (±1.9-3.5 km s-1 from systemic) shows a velocity gradient along the equatorial plane consistent with a rotating disk of ~=0farcs2 = 90 AU around a ~=0.3 ± 0.1 M&sun; source. The rotating disk is possibly Keplerian.
Conclusions: HH212 is the third Class 0 protostar with possible signatures of a Keplerian disk of radius >=30 AU. The warped geometry in our CS data suggests that this large Keplerian disk might result from misaligned magnetic and rotation axes during the collapse phase. The wide-angle CS flow suggests that disk winds may be present in this source.

Dates et versions

hal-02268294 , version 1 (20-08-2019)

Identifiants

Citer

C. Codella, S. Cabrit, F. Gueth, L. Podio, S. Leurini, et al.. The ALMA view of the protostellar system HH212. Astronomy and Astrophysics - A&A, 2014, 568, pp.L5. ⟨10.1051/0004-6361/201424103⟩. ⟨hal-02268294⟩
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