ALFALFA HI Content and Star Formation in Virgo Cluster Early-Type Dwarfs

TL;DR

This study uses ALFALFA survey data to analyze HI content and star formation in Virgo Cluster early-type dwarf galaxies, revealing low detection rates and environmental influences on their evolution.

Contribution

It provides the first systematic measurement of HI in Virgo early-type dwarfs and links HI presence to star formation and cluster environment effects.

Findings

Less than 2% of early-type dwarfs detected in HI

HI-detected dwarfs are often in outer cluster regions

HI presence correlates with ongoing star formation

Abstract

The ALFALFA (Arecibo Legacy Fast ALFA) blind survey is providing a census of HI in galaxies of all types in a range of environments. Here we report on ALFALFA results for Virgo Cluster early-type dwarfs between declinations of 4 and 16 degrees. Less than 2% of the Virgo early-type dwarf population is detected, compared to 70-80% of the Im/BCD dwarf population. Most of the dwarfs detected in HI show evidence for ongoing or recent star formation. Early-type galaxies with HI tend to be located in the outer regions of the cluster and to be brighter. Early-type dwarfs with HI may be undergoing morphological transition due to cluster environmental effects.