FAUST XII. Accretion streamers and jets in the VLA 1623-2417 protocluster
Abstract
The ALMA interferometer has played a key role in revealing a new component of the Sun-like star forming process: the molecular streamers, i.e. structures up to thousands of au long funnelling material non-axisymmetrically to discs. In the context of the FAUST ALMA LP, the archetypical VLA1623-2417 protostellar cluster has been imaged at 1.3 mm in the SO(56-45), SO(66-55), and SiO(5-4) line emission at the spatial resolution of 50 au. We detect extended SO emission, peaking towards the A and B protostars. Emission blue-shifted down to 6.6 km s-1 reveals for the first time a long (~ 2000 au) accelerating streamer plausibly feeding the VLA1623 B protostar. Using SO, we derive for the first time an estimate of the excitation temperature of an accreting streamer: 33 ± 9 K. The SO column density is ~ 1014 cm-2, and the SO/H2 abundance ratio is ~ 10-8. The total mass of the streamer is 3 × 10-3M⊙, while its accretion rate is 3-5 × 10-7M⊙ yr-1. This is close to the mass accretion rate of VLA1623 B, in the 0.6-3 × 10-7M⊙ yr-1 range, showing the importance of the streamer in contributing to the mass of protostellar discs. The highest blue- and red-shifted SO velocities behave as the SiO(5-4) emission, the latter species detected for the first time in VLA1623-2417: the emission is compact (100-200 au), and associated only with the B protostar. The SO excitation temperature is ~ 100 K, supporting the occurrence of shocks associated with the jet, traced by SiO.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 2024
- DOI:
- 10.1093/mnras/stae472
- arXiv:
- arXiv:2402.10258
- Bibcode:
- 2024MNRAS.528.7383C
- Keywords:
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- astrochemistry;
- stars: formation;
- ISM: Individual objects: VLA 1623-2417;
- ISM: kinematics and dynamics;
- ISM: molecules;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- accepted by MNRAS