The H alpha Galaxy Survey I. The galaxy sample, H alpha narrow-band observations and star formation parameters for 334 galaxies

TL;DR

This paper presents a comprehensive survey of 334 nearby galaxies, measuring their star formation rates and related parameters using H alpha imaging to understand star formation activity across galaxy types.

Contribution

It provides a large, uniform dataset of star formation indicators for a diverse sample of nearby galaxies, enabling detailed analysis of star formation trends.

Findings

Strong correlation between total star formation rate and galaxy Hubble type.

No significant trend between H alpha equivalent width and galaxy luminosity.

Star formation activity peaks in isolated Sc and Sbc galaxies.

Abstract

We discuss the selection and observations of a large sample of nearby galaxies, which we are using to quantify the star formation activity in the local Universe. The sample consists of 334 galaxies across all Hubble types from S0/a to Im and with recession velocities of between 0 and 3000 km/s. The basic data for each galaxy are narrow band H alpha plus [NII] and R-band imaging, from which we derive star formation rates, H alpha plus [NII] equivalent widths and surface brightnesses, and R-band total magnitudes. A strong correlation is found between total star formation rate and Hubble type, with the strongest star formation in isolated galaxies occurring in Sc and Sbc types. More surprisingly, no significant trend is found between H alpha plus [NII] equivalent width and galaxy R-band luminosity. More detailed analyses of the data set presented here will be described in subsequent papers.