Hα surface photometry of galaxies in nearby clusters

V. The survey completion

¹ Università degli Studi di Milano-Bicocca, Piazza delle scienze 3, 20126 Milano, Italy e-mail: giuseppe.gavazzi@mib.infn.it
² Laboratoire d'Astrophysique de Marseille, BP8, Traverse du Siphon, 13376 Marseille Cedex 12, France
³ Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching bei München, Germany
⁴ Instituto Nacional de Astrofísica, Optica y Electrónica, Apartado Postal 51. CP 72000 Puebla, Pue., México

Received: 18 July 2005
Accepted: 12 September 2005

Abstract

We present the Hα imaging observations of 273 late-type galaxies in the nearby rich galaxy clusters Virgo, A 1367, Coma, Cancer, Hercules and in the Great Wall, carried out primarily with the 2.1 m telescope of the San Pedro Martir Observatory (SPM) and with the ESO/3.6 m telescope. We derived the Hα+[NII] fluxes and equivalent widths. The Hα survey reached completion for an optically selected sample of nearby galaxies in and outside rich clusters. Taking advantage of the completeness of the data set, the dependence of Hα properties on the Hubble type was determined for late-type galaxies in the Virgo cluster. Differences in the gaseous content partly account for the large scatter of the Hα EW within each Hubble-type class. We studied the radial distributions of the Hα EW around Coma+A 1367 and the Virgo clusters in two luminosity bins. Luminous galaxies show a decrease in their average Hα EW in the inner ~1 virial radius, while low-luminosity galaxies do not show this trend.