ALMA discovery of a dual dense probably rotating outflow from a massive young stellar object G18.88MME
Abstract
We report the discovery of a very dense jet-like fast molecular outflow surrounded by a wide-angle wind in a massive young stellar object (MYSO) G18.88MME (stellar mass ~8 M⊙) powering an extended green object G18.89-0.47. Four cores MM1-4 are identified in the Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm continuum map (resolution ${\sim} 0.8\, \mathrm { arcsec}$) towards G18.88MME, and are seen at the centre of the emission structure (extent ~0.3 pc × 0.2 pc) detected in the ALMA map. G18.88MME is embedded in the core MM1 (mass ~13-18 M⊙), where no radio continuum emission is detected. The molecular outflow centred at MM1 is investigated in the SiO(5-4), HC3N(24-23) and 13CO(2-1) lines. The detection of HC3N in the outflow is rare in MYSOs and indicates its very high density. The position-velocity diagrams display a fast narrow outflow (extent ~28 000 AU) and a slower wide-angle more extended outflow towards MM1, and both of these components show a transverse velocity gradient indicative of a possible rotation. All these observed features together make G18.88MME as a unique object for studying the unification of the jet-driven and wind-driven scenarios of molecular outflows in MYSOs.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- September 2021
- DOI:
- 10.1093/mnrasl/slab070
- arXiv:
- arXiv:2106.09626
- Bibcode:
- 2021MNRAS.506L..45Z
- Keywords:
-
- stars: formation;
- stars: pre-main-sequence;
- ISM: clouds;
- H II regions;
- individual object: SDC18.888-0.476;
- ISM: jets and outflows;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 5 pages, 6 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society