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A Gas Dynamical Approach to a Face-on View of Our Galaxy

Published online by Cambridge University Press:  12 April 2016

Keiichi Wada ,
Yoshiaki Taniguchi ,
Asao Habe  and
Tetsuo Hasegawa
Keiichi Wada
Affiliation:
Center for Information Processing Education, Hokkaido University, Sapporo 060, Japan
Yoshiaki Taniguchi
Affiliation:
Department of Astronomy, Tohoku Univ., Sendai 980-77, Japan
Asao Habe
Affiliation:
Department of Physics., Hokkaido Univ. Sapporo 060, Japan
Tetsuo Hasegawa
Affiliation:
Institute of Astronomy, The Univ. of Tokyo, Mitaka, Tokyo 181, Japan

Extract

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Recently the bar model for our Galaxy has been an emerging consensus. Here, we investigate how a rotating bar-like bulge affects the global gas dynamics in a disk and compare the longitude-velocity (LV) maps from self-gravitating hydrodynamical simulations, which is based on Wada and Habe (1992), with observed maps of neutral hydrogen and carbon monoxide in the Galaxy. We found that the features on the numerical LV maps depend strongly on four factors: the pattern speed of the bar, the position angle of the Sun, the strength of the bar potential and the ratio of the gas mass to total dynamical mass. We conclude that our Galaxy has a rotating, weak, bar-like bulge (a/b ∼ 0.7) observed from nearly end on (θp < 20°). The allowed range of pattern speed of the bar is surprisingly narrow (19±5 km s−1 kpc−1) and is consistent with recent observations of bulge stars. Self-gravity of the interstellar matter is needed to account for the observed molecular ring at a radius of ∼ 4 kpc even if the gas mass fraction to the dynamical mass is small (about 5%).

Type
Posters for Part IX
Information
International Astronomical Union Colloquium , Volume 157: Barred Galaxies , 1996 , pp. 554 - 556
Copyright
Copyright © Astronomical Society of the Pacific 1996

References

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