The Central PNe Populations of External Galaxies with SAURON

TL;DR

This study uses SAURON integral-field observations to analyze the planetary nebulae populations in the central regions of M32 and M31, revealing differences linked to stellar metallicity and population properties.

Contribution

It provides new insights into the PNe luminosity functions in galaxy nuclei and their relation to stellar metallicity and horizontal-branch star populations.

Findings

Lack of bright PNe in M31's nucleus linked to near-solar metallicity.

Metallicity influences the HB star populations and PNe brightness.

Differences in PNe populations reflect underlying stellar population properties.

Abstract

Thanks to SAURON integral-field observations we uncovered the Planetary Nebulae (PNe) populations inhabiting the central and nuclear regions of our galactic neighbours M32 and M31, respectively, and discuss the significant differences between their corresponding PNe luminosity functions in light of the properties of their parent stellar populations. In particular, we conclude that the lack of bright PNe in the nuclear regions of M31 is likely linked to the nearly Solar value for the stellar metallicity, consistent with previous suggestions that a larger metallicity would bias the Horizontal-Branch (HB) populations toward bluer colors, with fewer red HB stars capable of producing PNe and more blue HB stars that instead could contribute to the far-UV flux that is observed in metal-rich early-type galaxies and, incidentally, also in the nucleus of M31.