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A study of the luminous and dark components of the dwarf irregular galaxy DDO 154 is presented. From the surface photometry, a scale length α^-1^ = 0. 5 kpc and a central surface brightness B (0) c_ = 23. 17 are derived for the stellar disk with mean colors typical of Im galaxies. The photometry of the brightest blue stars, combined with the likely association with the CVn I cloud, suggest a distance DELTA 4' and an indication that it may be declining in the very outer parts. The shape of the rotation curve, and the fact that for r > 2 kpc it is completely dominated by the dark component, allow one to constrain almost uniquely the parameters of the mass model. The final model has (M/LB_) _*_ = 1. 0 (Mₛun_/Lₛun_) for the stellar disk, a core radius rc_ = 3. 0 kpc, and a central density ρ₀_ = 0. 015 Mₛun_ pc^-3^ for the dark isothermal halo. At the last observed point (r = 7. 6 kpc), more than 90% of the mass is dark.
Carignan et al. (Fri,) studied this question.