Distance to the Low-velocity Cloud in the Direction of the High-velocity Compact Cloud CO-0.40-0.22

Yuhei Iwata, Haruka Kato, Daisuke Sakai, Tomoharu Oka

Research output: Contribution to journalArticle

1 Citation (Scopus)


CO-0.40-0.22 is a peculiar molecular cloud that is compact and has an extraordinary broad velocity width. It is found in the central molecular zone (CMZ) of our Galaxy. In this direction, there is another cloud with an H2O maser spot at a lower velocity. A collision with this low-velocity cloud could be responsible for the broad velocity width of CO-0.40-0.22. We performed phase-referencing very long baseline interferometry (VLBI) astrometry with VERA and detected the annual parallax of the H2O maser spot in the low-velocity cloud to be 0.33 ±0.14 mas, which corresponds to a distance of from the Sun. This implies that the low-velocity cloud is located in the Galactic disk on the near side of the CMZ.

Original languageEnglish
Article number18
JournalAstrophysical Journal
Issue number1
Publication statusPublished - 2017 May 1



  • astrometry
  • Galaxy: center
  • ISM: clouds
  • masers

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this