Vertical Distribution of Stars and Gas in a Galactic Disk

Jog, Chanda J (2005) Vertical Distribution of Stars and Gas in a Galactic Disk. [Preprint]

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Abstract

We study the vertical density distribution of stars and gas $(HI and H_2)$ in a galactic disk which is embedded in a dark mater halo. The new feature of this work is the inclusion of gas, and the gravitational coupling between stars and gas, which has led to a more realistic treatment of a multi-component galactic disk. The gas gravity is shown to be crucially important despite the low gas mass fraction. This approach physically explains the observed scaleheight distribution of all the three disk com- ponents, including the long-standing puzzle (Oort 1962) of a constant HI scaleheight observed in the inner Galaxy. The above model is applied to two external galaxies: NGC 891 and NGC 4565, and the stellar disk is shown to be not strictly flat as was long believed but rather it shows a moderate flaring of a factor of ~ 2 within the optical radius

Item Type:	Preprint
Publication:	Los Alamos National Laboratory, Preprint Archive, Astrophysics
Keywords:	galaxies: kinematics and dynamics - galaxies;ISM - galaxies;HI- galaxies;structure - galaxies;The Galaxy
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	23 Feb 2006
Last Modified:	19 Sep 2010 04:23
URI:	http://eprints.iisc.ac.in/id/eprint/5545

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