CO Multi-line Imaging of Nearby Galaxies (COMING). II. Transitions between atomic and molecular gas, diffuse and dense gas, gas and stars in the dwarf galaxy NGC 2976-猫眼课题宝

DOI：

10.1093/pasj/psx044

发表时间：

2017-08

期刊：

Publications of the Astronomical Society of Japan

影响因子：

2.3

通讯作者：

中科院分区：

物理与天体物理4区

文献类型：

作者：

Takuya Hatakeyama;N. Kuno;K. Sorai;H. Kaneko;Y. Miyamoto;K. Muraoka;M. Takeda;Kazuki Yanagitani;N. Kishida;M. Umei;Takahiro Tanaka;Yuto Tomiyasu;H. Nakanishi;Chey Saita;Saeko Ueno;D. Salak;N. Matsumoto;K. Morokuma-Matsui;H. Pan;N. Nakai

在这项研究中，我们介绍了利用Nobeama 45m望远镜对矮小星系NGC2976进行的12CO(J=1-0)、13CO(J=1-0)和C18O(J=1-0)同时观测的结果。我们研究了C©2017中的分子气体和恒星形成的性质。由牛津大学出版社代表日本天文学会出版。版权所有。如需权限，请发送电子邮件至：https://academic.oup.com/pasj/article-abstract/69/4/67/3916637/CO-Multi-line-Imaging-of-Nearby-Galaxies-COMING-II@oup.com，访客于2017年9月19日从日本下载67-2日本天文学会出版物(2017)，第69卷，第4期NGC2976。我们发现，根据螺旋星系的主要恒星盘，分子气体分数取决于总气体的表面密度和恒星形成速度。12Co(J=3-2)与12Co(J=1-0)的比值表明，分子气体的温度随分子气体表面密度的降低而升高。我们用堆积法测定了~(13)CO(J=1-0)。12Co(J=1-0)和13CO(J=1-0)的积分强度之比为27±11，表明在低表面密度区以扩散气相为主。得到了12Co(J=1-0)和C18O(J=1-0)的积分强度之比为21的下限。全气体表面密度与恒星形成率之间的关系符合2.08±0.11的幂指数关系，大于分子气体表面密度与恒星形成率之间的关系(1.62±0.17)。全气体表面密度与恒星形成率之间关系的陡峭斜率可归因于在∼10M表面密度下分子气体分数的迅速增加。分子气体的运动学表明，棒状特征是以刚体旋转曲线旋转的，而不是以一定的模式速度旋转。

In this study, we present the results of 12CO(J = 1–0), 13CO(J = 1–0), and C18O(J = 1–0) simultaneous observations of the dwarf galaxy NGC 2976 conducted as a part of the CO Multi-line Imaging of Nearby Galaxies (COMING) project using the Nobeyama 45 m telescope. We investigated the properties of the molecular gas and star formation in C © The Author 2017. Published by Oxford University Press on behalf of the Astronomical Society of Japan. All rights reserved. For Permissions, please email: journals.permissions@oup.com Downloaded from https://academic.oup.com/pasj/article-abstract/69/4/67/3916637/CO-Multi-line-Imaging-of-Nearby-Galaxies-COMING-II by guest on 19 September 2017 67-2 Publications of the Astronomical Society of Japan (2017), Vol. 69, No. 4 NGC 2976. We found that the molecular gas fraction depends on the surface densities of the total gas and the star formation rate, according to the main stellar disks of spiral galaxies. The ratio of 12CO(J = 3–2) to 12CO(J = 1–0) implies that the temperature of the molecular gas increases with decreases in the surface density of molecular gas. We detected 13CO(J = 1–0) by using the stacking method. The ratio between the integrated intensities of 12CO(J = 1–0) and 13CO(J = 1–0) was 27 ± 11. These ratios imply that the diffuse gas phase is dominant in low surface density regimes. We obtained a lower limit of the ratio between the integrated intensities of 12CO(J = 1–0) and C18O(J = 1–0) of 21. The relation between the surface densities of the total gas and the star formation rate followed a power-law index of 2.08 ± 0.11, which was larger than that between the surface densities of the molecular gas and the star formation rate (1.62 ± 0.17). The steep slope in the relation between the surface densities of the total gas and the star formation rate can be attributed to the rapid increase in the fraction of molecular gas at the surface density of ∼10 M . The kinematics of the molecular gas suggest that the bar-like feature rotates with a rigid-body rotation curve rather than a certain pattern speed.

CO Multi-line Imaging of Nearby Galaxies (COMING). II. Transitions between atomic and molecular gas, diffuse and dense gas, gas and stars in the dwarf galaxy NGC 2976

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