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arXiv · 0904.4305

The origin of large peculiar motions of star-forming regions and spiral structures of our Galaxy

Junichi Baba·Yoshiharu Asaki·Junichiro Makino·Makoto Miyoshi·Takayuki R. Saitoh·Keiichi Wada
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Abstract

Recent VLBI (Very Long Baseline Interferometer) observations determined the distances and proper motions of star-forming regions in spiral arms directly. They showed that star-forming regions and young stars have large peculiar motions, as large as 30 km/s with complex structures. Such a large peculiar motion is incompatible with the prediction of the standard theory of quasi-stationary spiral arms. We use a high-resolution, self-consistent N-body+hydrodynamical simulation to explore how the spiral arms are formed and maintained, and how star-forming regions move. We found that arms are not quasi-stationary but transient and recurrent, as suggested in alternative theories of spiral structures. Because of this transient nature of the spiral arms, star-forming regions exhibit a trend of large and complex non-circular motions, which is qualitatively consistent with the VLBI observations. Owing to this large non-circular motion, a kinematically estimated gas map of our Galaxy has a large systematic errors of ~2-3 kpc in the distance from the Sun.

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Junichi Baba, Yoshiharu Asaki, Junichiro Makino, Makoto Miyoshi, Takayuki R. Saitoh, Keiichi Wada. 2009-10-29. The origin of large peculiar motions of star-forming regions and spiral structures of our Galaxy. https://doi.org/10.1088/0004-637x/706/1/471

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