paper

Multiple outflows in the high-mass cluster forming region, G25.82-0.17

arXiv:2005.05006 · doi:10.3847/1538-4357/ab9100

Abstract

We present results of continuum and spectral line observations with ALMA and 22 GHz water (H $_{2}$ O) maser observations using KaVA and VERA toward a high-mass star-forming region, G25.82-0.17. Multiple 1.3 mm continuum sources are revealed, indicating the presence of young stellar objects (YSOs) at different evolutionary stages, namely an ultra-compact HII region, G25.82-E, a high-mass young stellar object (HM-YSO), G25.82-W1, and starless cores, G25.82-W2 and G25.82-W3. Two SiO outflows, at N-S and SE-NW orientations, are identified. The CH $_{3}$ OH 8 $_{- 1}$ -7 $_{0}$ E line, known to be a class I CH $_{3}$ OH maser at 229 GHz is also detected showing a mixture of thermal and maser emission. Moreover, the H $_{2}$ O masers are distributed in a region ~0.25" shifted from G25.82-W1. The CH $_{3}$ OH 22 $_{4}$ -21 $_{5}$ E line shows a compact ring-like structure at the position of G25.82-W1 with a velocity gradient, indicating a rotating disk or envelope. Assuming Keplerian rotation, the dynamical mass of G25.82-W1 is estimated to be $>$ 25 M $_{⊙}$ and the total mass of 20 M $_{⊙}$ -84 M $_{⊙}$ is derived from the 1.3 mm continuum emission. The driving source of the N-S SiO outflow is G25.82-W1 while that of the SE-NW SiO outflow is uncertain. Detection of multiple high-mass starless $/$ protostellar cores and candidates without low-mass cores implies that HM-YSOs could form in individual high-mass cores as predicted by the turbulent core accretion model. If this is the case, the high-mass star formation process in G25.82 would be consistent with a scaled-up version of low-mass star formation.

28 pages, 9 figures, accepted to ApJ