H-alpha images of early type galaxies with hot gas
- Arcetri, Osservatorio Astronomico, Florence (Italy) European Southern Observatory, Garching (Federal Republic of Germany)
H-alpha imaging observations of 13 early type galaxies with known X-ray fluxes are presented from the Einstein Observatory data, and long-slit spectroscopy of nine of these. H-alpha emission is detected in the central regions of ten objects. The line emission appears extended over a radius of 5-10 kpc, is generally peaked on the nucleus with regular elliptical isophotes, similar to the red continuum, although with a steeper radial distribution. Low surface brightness filamentary structure is also seen in a few cases (NGC 4406 and NGC 5846). To study the different phases of the interstellar medium in early type galaxies, the emissions due to hot (X-ray) and warm (H-alpha) gas are compared. On average, galaxies with a larger content of hot gas also show a more powerful line emission. However, the scatter in the relation is significant, and suggests that other parameters must play a role. The depth of the gravitational potential and/or the shape of the objects are probably important in determining the amount of gas present in early type galaxies. 50 refs.
- OSTI ID:
- 5503405
- Journal Information:
- Astronomical Journal; (United States), Vol. 101; ISSN 0004-6256
- Country of Publication:
- United States
- Language:
- English
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