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6.3. Physical conditions of the gas in the center of the nearby spiral galaxy IC 342

Published online by Cambridge University Press:  25 May 2016

J. L. Turner
J. L. Turner*
Affiliation:
Dept. of Physics & Astronomy UCLA, Los Angeles, CA 90095-1562

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One of our nearest neighbors is a large spiral galaxy with abundant molecular gas in its nucleus. IC 342, a face-on Scd galaxy at a distance of 1.8 Mpc, is close enough to give us a view of individual molecular clouds with millimeter interferometry. The CO distribution in the nucleus of IC 342 consists of two very open spiral arms (Lo et al. 1984; Ishizuki et al. 1990) that continue to within 50 pc of the dynamical center (Turner & Hurt 1992). The total extent of the nuclear “mini-spiral” is ~ 500 pc. Corresponding arms are observed in Hα (J.S. Young, private comm.). However, the Hα arms are systematically offset by 50-100 pc from the CO arms (Turner & Hurt 1992). The offset of the Hα arms to the outer, leading edge of the CO arms is consistent with a picture of density wave-induced star formation in the arms (Turner & Hurt 1992). Energy dissipation and angular momentum transfer in spiral arms is believed to drive a slow drift of gas inward; if this is the case, the molecular “mini-spiral” in IC 342 is short-lived, and will probably no longer exist in another 108 years.

Type
Part II. Nuclear Interstellar Medium
Information
Symposium - International Astronomical Union , Volume 184: The Central Regions of the Galaxy and Galaxies , 1998 , pp. 267 - 268
Copyright
Copyright © Kluwer 1998 

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