The stellar populations in the low luminosity, early-type galaxy NGC59

TL;DR

This study analyzes the stellar populations of the low luminosity galaxy NGC59, revealing its complex star formation history, extremely low metallicity, and implications for galaxy formation models.

Contribution

It provides detailed stellar population parameters for NGC59, highlighting its extended star formation and low metallicity, informing theories of galaxy assembly.

Findings

Presence of both old and young stars in NGC59

Extremely low metallicity [Z/H] ~ -1.1 to -1.6

Sub-solar [alpha/Fe] ratio indicating extended star formation

Abstract

Low luminosity galaxies may be the building blocks of more luminous systems. Southern African Large Telescope (SALT) observations of the low luminosity, early-type galaxy NGC59 are obtained and analysed. These data are used to measure the stellar population parameters in the centre and off-centre regions of this galaxy, in order to uncover its likely star formation history. We find evidence of older stars, in addition to young stars in the emission line regions. The metallicity of the stellar population is constrained to be [Z/H] ~ -1.1 to -1.6, which is extremely low, even for this low luminosity galaxy, since it is not classed as a dwarf spheroidal galaxy. The measured [alpha/Fe] ratio is sub-solar, which indicates an extended star formation history in NGC59. If such objects formed the building blocks of more massive, early-type galaxies, then they must have been gaseous mergers, rather than dry mergers, in order to increase the metals to observed levels in luminous, early-type galaxies.