SIMBAD references

We present integrated Hα measurements obtained from imaging observations of 98 late-type galaxies, primarily selected in the Coma supercluster. These data, combined with Hα photometry from the literature, include a magnitude-selected sample of spiral (Sa to Irr) galaxies belonging to the ``Great Wall'' complete up to m<sub>p</sub> = 15.4, and thus composed of galaxies brighter than M<sub>p</sub> = -18.8 (H<sub>0</sub> = 100 km.s<sup>–1</sup>.Mpc<sup>–1</sup>). The frequency distribution of the Hα equivalent width, determined for the first time from an optically complete sample, is approximately Gaussian, peaking at EW ∼ 25 Å. We find that, at the present limiting luminosity, the star formation properties of spiral + Irr galaxy members of the Coma and A1367 Clusters do not differ significantly from those of the isolated ones belonging to the Great Wall. The present analysis confirms the well-known increase of the current massive star formation rate (SFR) with Hubble type. Moreover, perhaps a more fundamental anticorrelation exists between the SFR and the mass of disk galaxies: low-mass spirals and dwarf systems have present SFRs ∼50 times higher than giant spirals. This result is consistent with the idea that disk galaxies are coeval, evolving as ``closed systems'' with exponentially declining SFR, and that the mass of their progenitor protogalaxies is the principal parameter governing their evolution. Massive systems having high initial efficiency of collapse, or a short collapse timescale, have retained little gas to feed the present epoch of star formation. These findings support the conclusions of Gavazzi & Scodeggio, who studied the color-mass relation of a local galaxy sample, and agree with the analysis by Cowie et al., who traced the star formation history of galaxies up to z > 1.