The Distribution of the Diffuse Ionized Interstellar Medium Perpendicular to the Disk of the Edge-On Galaxy NGC891
Abstract
We report the detection of an Hα-emitting component of the diffuse ionized interstellar medium with a scale height of up to 1 kpc in the edge-on galaxy NGC 891. The presented data show individual structures out to ~4.5 kpc above the plane. The distribution is very inhomogeneous and we characterize three different regions by the observed scale height and the presence of a filamentary structure. The emitting gas is analogous to the diffuse low-density, 2-3 kpc thick layer of warm ionized gas observed in our Galaxy. In NGC 891 the properties of this gas phase, such as scale height and surface density, are directly related to star forming processes in the underlying disk. Individual structures are compared with predictions by models of the interstellar medium driven by multiple supernova events. The estimated total mass of this diffuse component of the ionized gas is 4 x 10^8^ M_sun_. Owing to the large scale it contributes significantly to the total amount of atomic hydrogen in regions high above the plane.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- June 1990
- Bibcode:
- 1990A&A...232L..15D
- Keywords:
-
- Diffuse Radiation;
- Galactic Structure;
- Interstellar Gas;
- Ionized Gases;
- Absorption Spectra;
- Emission Spectra;
- H Alpha Line;
- Astrophysics