ALMA view of the Galactic super star cluster RCW 38 at 270 au resolution

Kazufumi Torii, Kazuki Tokuda, Kengo Tachihara, Toshikazu Onishi, Yasuo Fukui

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


We report millimeter/submillimeter continuum and molecular line observations of the Galactic super star cluster RCW 38, obtained from the Atacama Large Millimeter/Submillimeter Array with a minimum angular resolution of 0.''17 × 0.''15 (≃ 289 au × 255 au). The C18O image reveals many massive condensations embedded within filamentary structures extending along the northwest-southeast direction in the center of cluster. The condensations have sizes of 0.01-0.02 pc, H2 column densities of 1023-1024 cm−2, and H2 masses of 10-130 M⊙. In addition, the 233 GHz continuum image reveals two dense, small millimeter-sources with radii of 460 and 200 au (Source A and Source B). Source A is embedded within the most massive C18O condensation, whereas no counterpart is seen for Source B. The masses of Source A and Source B are estimated as 13 and 3 M⊙ at the optically thin limit, respectively. The C18O emission shows a velocity gradient of 2 km s−1 at the central 2000 au of Source A, which could be interpreted as a Keplerian rotation with a central mass of a few M⊙ or infall motion of gas. Further, the ALMA 12CO data reveal that Source A and Source B are associated with molecular outflows exhibiting maximum velocities of ∼30-70 km s−1. The outflows have short dynamical timescales of <1000 yr and high-mass outflow rates of ∼10−4-10−3 M⊙ yr−1. These observational signatures suggest an early evolutionary phase of the massive star formation in Source A and Source B.

Original languageEnglish
Pages (from-to)205-219
Number of pages15
JournalPublications of the Astronomical Society of Japan
Issue number1
Publication statusPublished - Feb 1 2021
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'ALMA view of the Galactic super star cluster RCW 38 at 270 au resolution'. Together they form a unique fingerprint.

Cite this