The Planetary Nebulae Populations in the Local Group

TL;DR

This paper reviews the use of planetary nebulae as tracers of stellar populations in the Local Group, highlighting empirical properties and the need for detailed physical studies of nearby systems.

Contribution

It emphasizes the importance of studying Local Group galaxies to understand planetary nebulae properties across different stellar environments.

Findings

Invariant bright cut-off of planetary nebulae luminosity function

Correlations between PN specific number and stellar population properties

Need for detailed physical studies of nearby PN populations

Abstract

Planetary nebulae have been used as tracers of light and kinematics for the stellar populations in early-type galaxies since more than twenty years. Several empirical properties have surfaced: for example the invariant bright cut-off of the planetary nebulae luminosity function and correlations of the luminosity specific PN number with the integrated properties of the parent stellar populations. These observed properties are poorly understood in terms of a simple model of a ionized nebula expanding around a non-evolving central star. In order to make further steps, we need to study self-contained systems at know distances whose PN populations are sufficiently nearby to permit investigation into their physical properties. The galaxies in the Local Group represent a valid proxies to study these late phases of evolved stellar populations with a spread of metallicities, $\alpha$-element enhancements, and star forming histories.