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Title: PHYSICAL CONTACT BETWEEN THE +20 km s{sup −1} CLOUD AND THE GALACTIC CIRCUMNUCLEAR DISK

Abstract

This paper reports the discovery of evidence for physical contact between the Galactic circumnuclear disk (CND) and an exterior giant molecular cloud. The central 10 pc of our Galaxy has been imaged in the HCN J  = 1–0, HCO{sup +} J  = 1–0, CS J  = 2–1, H{sup 13}CN J  = 1–0, SiO J  = 2–1, SO N{sub J}  = 2{sub 3}–1{sub 2}, and HC{sub 3}N J  = 11–10 lines using the Nobeyama Radio Observatory 45 m radio telescope. Based on our examination of the position–velocity maps of several high-density probe lines, we have found that an emission “bridge” may be connecting the +20 km s{sup −1} cloud (M–0.13–0.08) and the negative-longitude extension of the CND. Analyses of line intensity ratios imply that the chemical property of the bridge is located between the +20 km s{sup −1} cloud and the CND. We introduce a new interpretation that a part of the CND may be colliding with the 20 km s{sup −1} cloud and the collision may be responsible for the formation of the bridge. Such collisional events could promote mass accretion onto the CND or into the inner ionized cavity, which may be further tested by proper motion studies.

Authors:
;  [1];  [2]
  1. School of Fundamental Science and Technology, Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama, Kanagawa 223-8522 (Japan)
  2. Department of Physics, Institute of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama, Kanagawa 223-8522 (Japan)
Publication Date:
OSTI Identifier:
22661386
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 834; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CHEMICAL PROPERTIES; CLOUDS; DENSITY; GALAXY NUCLEI; HYDROCYANIC ACID; IMAGES; MILKY WAY; MOLECULES; NITRILES; PROBES; PROPER MOTION; RADIO TELESCOPES; SILICON OXIDES

Citation Formats

Takekawa, Shunya, Oka, Tomoharu, and Tanaka, Kunihiko, E-mail: shunya@aysheaia.phys.keio.ac.jp. PHYSICAL CONTACT BETWEEN THE +20 km s{sup −1} CLOUD AND THE GALACTIC CIRCUMNUCLEAR DISK. United States: N. p., 2017. Web. doi:10.3847/1538-4357/834/2/121.
Takekawa, Shunya, Oka, Tomoharu, & Tanaka, Kunihiko, E-mail: shunya@aysheaia.phys.keio.ac.jp. PHYSICAL CONTACT BETWEEN THE +20 km s{sup −1} CLOUD AND THE GALACTIC CIRCUMNUCLEAR DISK. United States. doi:10.3847/1538-4357/834/2/121.
Takekawa, Shunya, Oka, Tomoharu, and Tanaka, Kunihiko, E-mail: shunya@aysheaia.phys.keio.ac.jp. Tue . "PHYSICAL CONTACT BETWEEN THE +20 km s{sup −1} CLOUD AND THE GALACTIC CIRCUMNUCLEAR DISK". United States. doi:10.3847/1538-4357/834/2/121.
@article{osti_22661386,
title = {PHYSICAL CONTACT BETWEEN THE +20 km s{sup −1} CLOUD AND THE GALACTIC CIRCUMNUCLEAR DISK},
author = {Takekawa, Shunya and Oka, Tomoharu and Tanaka, Kunihiko, E-mail: shunya@aysheaia.phys.keio.ac.jp},
abstractNote = {This paper reports the discovery of evidence for physical contact between the Galactic circumnuclear disk (CND) and an exterior giant molecular cloud. The central 10 pc of our Galaxy has been imaged in the HCN J  = 1–0, HCO{sup +} J  = 1–0, CS J  = 2–1, H{sup 13}CN J  = 1–0, SiO J  = 2–1, SO N{sub J}  = 2{sub 3}–1{sub 2}, and HC{sub 3}N J  = 11–10 lines using the Nobeyama Radio Observatory 45 m radio telescope. Based on our examination of the position–velocity maps of several high-density probe lines, we have found that an emission “bridge” may be connecting the +20 km s{sup −1} cloud (M–0.13–0.08) and the negative-longitude extension of the CND. Analyses of line intensity ratios imply that the chemical property of the bridge is located between the +20 km s{sup −1} cloud and the CND. We introduce a new interpretation that a part of the CND may be colliding with the 20 km s{sup −1} cloud and the collision may be responsible for the formation of the bridge. Such collisional events could promote mass accretion onto the CND or into the inner ionized cavity, which may be further tested by proper motion studies.},
doi = {10.3847/1538-4357/834/2/121},
journal = {Astrophysical Journal},
number = 2,
volume = 834,
place = {United States},
year = {Tue Jan 10 00:00:00 EST 2017},
month = {Tue Jan 10 00:00:00 EST 2017}
}