| Abstract | A class of galaxies has been identified whose members show spiral arms but not the clumpy regions that are indicative of recent star formation in those arms. Neutral-hydrogen observations have been made of five of these smooth-arm spirals in three galaxy clusters, using the 305-m Arecibo telescope. Four nonsmooth spirals in two of the same clusters were also observed. Three of the four nonsmooth galaxies were detected and found to be deficient in neutral hydrogen with respect to 'field' galaxies. One of the smooth-arm spirals was definitely detected, and a second one was detected at a low confidence level. Upper limits substantially below the neutral-hydrogen levels for actively star-forming spirals were established for the other three smooth spirals. These observations argue that smooth-arm spirals are gas deficient even when compared to their clumpy spiral neighbors in rich clusters. |
