An Ordered Envelope-Disk Transition in the Massive Protostellar Source G339.88-1.26

Yichen Zhang, Jonathan C. Tan, Nami Sakai, Kei E.I. Tanaka, James M. De Buizer, Mengyao Liu, Maria T. Beltrán, Kaitlin Kratter, Diego Mardones, Guido Garay

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

We report molecular line observations of the massive protostellar source G339.88-1.26 with the Atacama Large Millimeter/Submillimeter Array. The observations reveal a highly collimated SiO jet extending from the 1.3 mm continuum source, which connects to a slightly wider but still highly collimated CO outflow. Rotational features perpendicular to the outflow axis are detected in various molecular emissions, including SiO, SO 2 , H 2 S, CH 3 OH, and H 2 CO emissions. Based on their spatial distributions and kinematics, we find that they trace different parts of the envelope-disk system. The SiO emission traces the disk and inner envelope in addition to the jet. The CH 3 OH and H 2 CO emissions mostly trace the infalling-rotating envelope and are enhanced around the transition region between envelope and disk, i.e., the centrifugal barrier. The SO 2 and H 2 S emissions are enhanced around the centrifugal barrier and also trace the outer part of the disk. Envelope kinematics are consistent with rotating-infalling motion, while those of the disk are consistent with Keplerian rotation. The radius and velocity of the centrifugal barrier are estimated to be about 530 au and 6 , respectively, leading to a central mass of about 11 M o , consistent with estimates based on spectral energy distribution fitting. These results indicate that an ordered transition from an infalling-rotating envelope to a Keplerian disk through a centrifugal barrier, accompanied by changes of types of molecular line emissions, is a valid description of this massive protostellar source. This implies that at least some massive stars form in a similar way to low-mass stars via core accretion.

Original languageEnglish (US)
Article number73
JournalAstrophysical Journal
Volume873
Issue number1
DOIs
StatePublished - Jan 1 2019

Keywords

  • ISM: individual objects (G339.88-1.26)
  • ISM: jets and outflows
  • ISM: kinematics and dynamics
  • ISM: molecules
  • stars: formation
  • stars: massive

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Zhang, Y., Tan, J. C., Sakai, N., Tanaka, K. E. I., De Buizer, J. M., Liu, M., Beltrán, M. T., Kratter, K., Mardones, D., & Garay, G. (2019). An Ordered Envelope-Disk Transition in the Massive Protostellar Source G339.88-1.26. Astrophysical Journal, 873(1), [73]. https://doi.org/10.3847/1538-4357/ab0553