Michigan 160 - Internal kinematics and the cosmic distance scale

The kinematics and mass distribution of the emission-line irregular galaxy Michigan 160 have been studied, and the results are reported. The velocity field is adequately fitted by a rotating, tilted disk model in which velocities are solid body to about 50 arcsec and constant at 51 + or - 2 km/s thereafter. Central asymmetries are present and may be explained either by barlike or by warp distortions. The physical basis of these distortions appears to be the overall ringlike mass distribution. The kinematics and mass distribution are consistent with little or no dark matter content and an absolute distance of 41.8 + or - 4.0 Mpc. This distance is based on a direct fit of the observed H I and optical brightness distributions to the observed velocity field. It is proposed that the present method will make a substantial contribution to the measurement of distances over cosmologically significant scales. 53 refs