Halpha3: an Halpha imaging survey of HI selected galaxies from ALFALFA. V: The Coma Supercluster survey completion

TL;DR

This paper presents a comprehensive Halpha imaging survey of HI-selected galaxies in the Coma Supercluster, providing new data on star formation rates across different galaxy types and environments.

Contribution

It offers the first complete census of star formation in local gas-rich galaxies within the Coma Supercluster, using a large, HI-selected sample.

Findings

97% complete sample of 603 galaxies from ALFALFA survey.

Provides Halpha-based star formation rates for diverse galaxy types.

Enables comparison of star formation in different environments.

Abstract

Neutral hydrogen represents the major observable baryonic constituent of galaxies that fuels the formation of stars through the transformation in molecular hydrogen. The emission of the hydrogen recombination line Halpha is the most direct tracer of the process that transforms gas (fuel) into stars. We continue to present Halpha3 (acronym for Halpha-alpha-alpha), an extensive Halpha+[NII] narrow-band imaging campaign of galaxies selected from the HI Arecibo Legacy Fast ALFA Survey (ALFALFA), using the instrumentation available at the San Pedro Martir observatory (Mexico). In only four years since 2011 we were able to complete in 48 nights the Halpha imaging observations of 724 galaxies in the region of the Coma supercluster 10^h < R.A. <16^h; 24^o < Dec. <28^o and 3900<cz<9000 kms^{-1}. Of these, 603 are selected from the HI Arecibo Legacy Fast ALFA Survey (ALFALFA) and constitute a 97% complete sample. They provide for the first time a complete census of the massive star formation properties of local gas-rich galaxies belonging to different environments (cluster vs filaments), morphological type (spirals vs dwarf Irr), over a wide range of stellar mass (10^{8}-10^{11.5} Modot) in the Coma Supercluster. The present Paper V provides the Halpha data and the derived star formation rates for the observed galaxies.