An intermediate-velocity H I cloud falling to the galactic disk; Possible evidence for low-metallicity H I gas originating outside the galactic disk
Fukui Y, Koga M, Maruyama S, Hayakawa T, Okamoto R, Yamamoto H, Tachihara K, Shelton R, Sasaki M (2021)
Publication Type: Journal article
Publication year: 2021
Journal
Book Volume: 73
Pages Range: S117-S128
DOI: 10.1093/pasj/psy120
Abstract
We found that an intermediate-velocity cloud (IVC), IVC 86-36, in H I 21cm emission shows a head-tail distribution toward the Galactic plane with marked parallel filamentary streamers, which is extended over 40 degrees in the sky. The distance of IVC 86-36 is constrained to be less than similar to 3kpc from absorption of a background star as determined from optical spectroscopy. There is a bridge feature in velocity between the IVC and the local interstellar medium with velocity separation of similar to 50kms(-1), which may indicate dynamical interaction of the IVC with the disk. If the interaction is correct, the distance estimate d of the IVC ranges from 200pc to 3kpc, and the mass of the IVC head is estimated to be 7 x 10(3)(d/1 kpc)(2) M-circle dot . The IVC shares similar properties to the Smith Cloud located at 12kpc, including the head-tail distribution, streamers, and bridge feature, while the mass of the IVC is less than similar to 0.1 of the Smith Cloud. A comparison between the H I and the Planck/IRAS dust emission indicates that the dust emission of IVC 86-36 is not detectable in spite of its H I column density of 2 x 10(20)cm(-2), indicating a low metallicity for IVC 86-36, reduced by a factor of less than or similar to 0.2 as compared with the solar neighbor. We conclude that IVC 86-38 is an infalling cloud which likely originated in the low-metallicity environment of the Galactic halo or the Magellanic system.
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Japan (JP)
United States (USA) (US)How to cite
APA:
Fukui, Y., Koga, M., Maruyama, S., Hayakawa, T., Okamoto, R., Yamamoto, H.,... Sasaki, M. (2021). An intermediate-velocity H I cloud falling to the galactic disk; Possible evidence for low-metallicity H I gas originating outside the galactic disk. Publications of the Astronomical Society of Japan, 73, S117-S128. https://doi.org/10.1093/pasj/psy120
MLA:
Fukui, Yasuo, et al. "An intermediate-velocity H I cloud falling to the galactic disk; Possible evidence for low-metallicity H I gas originating outside the galactic disk." Publications of the Astronomical Society of Japan 73 (2021): S117-S128.
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