Astronomy and Astrophysics – Astronomy
Scientific paper
Dec 1989
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1989apj...347..760c&link_type=abstract
Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 347, Dec. 15, 1989, p. 760-770. Research supported by NSERC.
Astronomy and Astrophysics
Astronomy
192
Astronomical Photometry, Dwarf Galaxies, H I Regions, Irregular Galaxies, Mass Distribution, Radio Astronomy, Blue Stars, Galactic Rotation, Isophotes, Spectrophotometry, Stellar Spectrophotometry
Scientific paper
A study of the luminous and dark components of the dwarf irregular galaxy DDO 154 is presented. A scale length of 0.5 kpc and a central surface brightness B(0)v = 23.17 are derived for the stellar disk with mean colors typical of Im galaxies. A distance of 4.0 MPc or less is suggested. DDO 154 is one of the most gas-rich galaxies known with M(H I)/L(B) = 5.4. The H I disk reaches nearly 5 Holmberg diameters. The rotation curve is derived unambiguously out to 15 optical scale lengths. There is a clear flattening of the rotation curve for r more than 4 arcmin and an indication that it may be declining in the very outer parts. The shape of the rotation curve and the fact that it is completely dominated by the dark component for r greater than 2 kpc are used to find M/L(B)(asterisk) = 1.0(M-solar/L-solar) for the stellar disk, a core radius of 3.0 kpc, and a central density of 0.015 solar maass/cu pc for the dark isothermal halo.
Beaulieu Sylvie
Carignan Claude
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