Optical and H I studies of the gas-rich dwarf irregular galaxy DDO 154

摘要: A study of the luminous and dark components dwarf irregular galaxy DDO 154 is presented. scale length 0.5 kpc a central surface brightness B(0)v = 23.17 are derived for stellar disk with mean colors typical Im galaxies. distance 4.0 MPc or less suggested. one most gas-rich galaxies known M(H I)/L(B) 5.4. The H I reaches nearly 5 Holmberg diameters. rotation curve unambiguously out to 15 optical lengths. There clear flattening r more than 4 arcmin an indication that it may be declining in very outer parts. shape fact completely dominated by component greater 2 used find M/L(B)(asterisk) 1.0(M-solar/L-solar) disk, core radius 3.0 kpc, density 0.015 solar maass/cu pc isothermal halo. 40 refs.