| Abstract | H I 21-cm line measurements of 27 blue compact galaxies with optical emission lines and partly compact galaxies are presented and discussed. The general properties of these objects are compared with those of Hubble-sequence galaxies through relations between various parameters. It is shown that partly compact galaxies are normal, whereas blue compact ones are characterized by a high and nearly constant mean H I surface density, exceeding that of normal galaxies by a factor of 2 to 4. This result implies either a high H I volume density or a large H I extent, an alternative which cannot be tested due to insufficient spatial resolution. Various indications suggest that these blue compact objects could extend the Hubble sequence beyond irregular I galaxies. The present analysis is in agreement with the conclusions of Searle et al. (1973) concerning the nature of anomalously blue compact galaxies; i.e., normal dwarfs in a burst state or young galaxies. |
