Exploring the Interstellar Media of Optically Compact Dwarf Galaxies

TL;DR

This study investigates the interstellar media of eight optically compact blue dwarf galaxies using multi-wavelength data, revealing diverse HI disk sizes and an unusually large HI halo in one galaxy, contributing to understanding dwarf galaxy structure.

Contribution

It provides detailed HI and optical imaging of compact dwarf galaxies, highlighting the diversity in HI disk sizes and identifying an exceptional case with an extensive HI halo.

Findings

One galaxy has an HI halo extending 58 r-band scale lengths.

HI radii range from 9.3 to 26 times the optical scale length.

The galaxy ADBS 113845+2008 has an unusually large HI disk.

Abstract

We present new Very Large Array HI spectral line, archival Sloan Digital Sky Survey, and archival Spitzer Space Telescope imaging of eight star-forming blue compact dwarf galaxies that were selected to be optically compact (optical radii less than 1 kpc). These systems have faint blue absolute magnitudes (M_B >= -17), ongoing star formation (based on emission-line selection by the H alpha or [OIII] lines), and are nearby (mean velocity = 3315 km/s = 45 Mpc). One galaxy in the sample, ADBS 113845+2008, is found to have an HI halo that extends 58 r-band scale lengths from its stellar body. In contrast, the rest of the sample galaxies have HI radii to optical-scale-length ratios ranging from 9.3 to 26. The size of the HI disk in the "giant disk" dwarf galaxy ADBS 113845+2008 appears to be unusual as compared to similarly compact stellar populations.