| Abstract | The authors present CCD images in B, R, I, Hα and long-slit spectroscopy of Ho IX, a dwarf irregular galaxy situated close to M81. Photometry of the resolved stars to magnitude limits of B = 23m.8, R = 23m.8, and I = 23m.0 is used to construct colour-magnitude and colour-colour diagrams. The authors also discuss the photometry of the background light distribution of the subthreshold stars. A revised distance modulus of m-M = 30m is estimated. The blue, high-mass stars are concentrated towards the center of the galaxy and in at least three OB associations. The blue-to-red supergiant ratio indicates a more or less constant star formation rate within the last 107yr. It is proposed that Ho IX has just entered a quiescent phase of its star formation due to lack of interstellar material. |
