| Abstract | Results are reported for an unsuccessful attempt to detect 21-cm H I line emission from Stephan's Quintet in the velocity interval corresponding to redshifts of 1000 to 6000 km/s. An upper limit of 500 million solar masses is obtained for the neutral hydrogen mass in the velocity range from 1000 to 5600 km/s. Several other properties of the galaxies constituting Stephan's Quintet are derived from the present observations, including systematic velocities, total profile widths, profile integrals, and neutral hydrogen masses. The observations are shown to be completely consistent with the 'standard' hypothesis that the galaxies in the Quintet are at the distances appropriate to their redshifts; i.e., that NGC 7320 is a low-mass Sc galaxy projected against 'Stephan's Quartet'. However, it is also noted that the observations do not disprove the alternative hypothesis of some noncosmological contribution to the redshifts. |
