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Molecular Composition of Local Dwarf Galaxies: Astrochemistry in Low-metallicity Environments

Published online by Cambridge University Press:  30 October 2019

Yuri Nishimura
Affiliation:
Institute of Astronomy, The University of Tokyo email: [email protected] Chile Observatory, National Astronomical Observatory of Japan
Takashi Shimonishi
Affiliation:
Frontier Research Institute for Interdisciplinary Sciences, Tohoku University Astronomical Institute, Tohoku University
Yoshimasa Watanabe
Affiliation:
Faculty of Pure and Applied Sciences, University of Tsukuba Tomonaga Center for the History of the Universe, University of Tsukuba
Nami Sakai
Affiliation:
RIKEN
Yuri Aikawa
Affiliation:
Department of Astronomy, The University of Tokyo
Akiko Kawamura
Affiliation:
Chile Observatory, National Astronomical Observatory of Japan
Kotaro Kohno
Affiliation:
Institute of Astronomy, The University of Tokyo email: [email protected]
Satoshi Yamamoto
Affiliation:
Research Center for the Early Universe, The University of Tokyo
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Abstract

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To investigate molecular composition of low-metallicity environments, we conducted spectral line survey observations in the 3 mm band toward three dwarf galaxies, the Large Magellanic Cloud, IC 10, and NGC 6822 with the Mopra 22 m, the Nobeyama 45 m and the IRAM 30 m, respectively. The rotational transitions of CCH, HCN, HCO+, HNC, CS, SO, 13CO, and 12CO were detected in all three galaxies. We found that the spectral intensity patterns are similar to one another regardless of star formation activities. Compared with Solar-metallicity environments, the molecular compositions of dwarf galaxies are characterized by (1) deficient nitrogen-bearing molecules and (2) enhanced CCH and suppressed CH3OH. These are interpreted (1) as a direct consequence of the lower elemental abundance of nitrogen, and (2) as a consequence of extended photon dominated regions in cloud peripheries due to the lower abundance of dust grains, respectively.

Type
Contributed Papers
Copyright
© International Astronomical Union 2019 

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