Star formation in low-density regions of galactic disks

TL;DR

This paper explores how star formation occurs in the low-density, gravitationally stable regions of galactic disks, revealing similarities between low-surface-brightness galaxies and the outer regions of normal spirals, with implications for understanding star formation efficiency.

Contribution

It demonstrates that star formation in low-density galactic regions shares characteristics across different galaxy types and discusses processes that can trigger star formation under these conditions.

Findings

Star formation occurs in gravitationally stable, low-density disks.

Star formation efficiency correlates with disk brightness.

Similar star formation mechanisms operate in LSB galaxies and outer spiral disks.

Abstract

We argue that star formation in the disks of low-surface-brightness (LSB) galaxies shares a similar nature with that occurring in the far outer regions of normal-brightness spiral galaxies, such as those with the extended ultraviolet (XUV) disks. In both cases, stars are born in gravitationally stable disks with an extremely low average gas density (on kiloparsec scales), and the efficiency of this process depends on a disk brightness in a similar way. Processes which can stimulate star formation under these conditions are shortly discussed.