Asymptotic Giant Branch Stars in the Sculptor Dwarf Spheroidal Galaxy

TL;DR

This study presents near-infrared photometry of the Sculptor dwarf galaxy, identifying carbon Mira variables, analyzing their properties, and exploring the period-age relation and mass-loss characteristics of these evolved stars.

Contribution

It provides the first detailed analysis of AGB variables in Sculptor, including their periods, metallicities, and mass-loss rates, linking Mira properties to stellar evolution in dwarf galaxies.

Findings

Identification of two carbon Mira variables with periods of 189 and 554 days.

Evidence for a period-age relation among Local Group Mira variables.

Mass-loss rate of the long-period Mira consistent with other Local Group galaxies.

Abstract

JHK_S photometry is presented for a 35 arcmin square field centred on the Sculptor dwarf spheroidal galaxy. With the aid of published kinematic data definite galaxy members are identified and the width in J-K of the colour-magnitude diagram is shown to be consistent with an old population of stars with a large range in metal abundance. We identify two Asymptotic Giant Branch variables, both carbon Miras, with periods of 189 and 554 days, respectively, and discuss their ages, metallicities and mass loss as well as their positions in the Mira period-luminosity diagram. There is evidence for a general period-age relation for Local Group Miras. The mass-loss rate for the 554-day variable, MAG29, appears to be consistent with that found for Miras of comparable period in other Local Group galaxies.