An H alpha Imaging Survey of the Low-surface-brightness Galaxies Selected from the Fall Sky Region of the 40% ALFALFA HI Survey

摘要

We present the observed H alpha flux and derived star formation rates (SFRs) for a fall sample of low-surface-brightness galaxies (LSBGs). The sample is selected from the fall sky region of the 40% ALFALFA HI Survey-SDSS DR7 photometric data, and all the H alpha images were obtained using the 2.16 m telescope, operated by the National Astronomy Observatories, Chinese Academy of Sciences. A total of 111 LSBGs were observed and H alpha flux was measured in 92 of them. Though almost all the LSBGs in our sample are HI-rich, their SFRs, derived from the extinction and filter-transmission-corrected H alpha flux, are less than 1M(circle dot) yr(-1). LSBGs and star-forming galaxies have similar HI surface densities, but LSBGs have much lower SFRs and SFR surface densities than starforming galaxies. Our results show that LSBGs deviate from the Kennicutt-Schmidt law significantly, which indicates that they have low star formation efficiency. The SFRs of LSBGs are close to average SFRs in Hubble time and support previous arguments that most of the LSBGs are stable systems and they tend to seldom contain strong interactions or major mergers in their star formation histories.