The First Bird's-eye View of a Gravitationally Unstable Accretion Disk in High-mass Star Formation

Kazuhito Motogi, Tomoya Hirota, Masahiro N. Machida, Yoshinori Yonekura, Mareki Honma, Shigehisa Takakuwa, Satoki Matsushita

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

We report on the first bird's-eye view of the innermost accretion disk around the high-mass protostellar object G353.273+0.641, taken by Atacama Large Millimeter/submillimeter Array long baselines. The disk traced by dust continuum emission has a radius of 250 au, surrounded by the infalling rotating envelope traced by thermal CH3OH lines. This disk radius is consistent with the centrifugal radius estimated from the specific angular momentum in the envelope. The lower-limit envelope mass is ∼5-7 M and accretion rate onto the stellar surface is 3 × 10-3 M yr-1 or higher. The expected stellar age is well younger than 104 yr, indicating that the host object is one of the youngest high-mass objects at present. The disk mass is 2-7 M, depending on the dust opacity index. The estimated Toomre's Q parameter is typically 1-2 and can reach 0.4 at the minimum. These Q values clearly satisfy the classical criteria for gravitational instability, and are consistent with recent numerical studies. Observed asymmetric and clumpy structures could trace a spiral arm and/or disk fragmentation. We found that 70% of the angular momentum in the accretion flow could be removed via the gravitational torque in the disk. Our study has indicated that the dynamical nature of a self-gravitating disk could dominate the early phase of high-mass star formation. This is remarkably consistent with the early evolutionary scenario of a low-mass protostar.

Original languageEnglish
Article numberL25
JournalAstrophysical Journal Letters
Volume877
Issue number2
DOIs
Publication statusPublished - Jun 1 2019

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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