Seimei KOOLS-IFU mapping of the gas and dust distributions in Galactic PNe: Unveiling the origin and evolution of Galactic halo PN H4-1

TL;DR

This study uses advanced spectroscopic data to analyze the gas and dust in the Galactic halo planetary nebula H4-1, revealing its progenitor's evolution, binary interactions, and chemical composition.

Contribution

It provides the first detailed gas and dust mapping of H4-1 using KOOLS-IFU spectra and introduces a data-driven method to derive elemental abundances and masses.

Findings

Progenitor star had an initial mass of ~1.87 Msun

H4-1's chemical abundances are explained by binary evolution models

The nebula's structure includes an ellipsoidal shape and flattened disk

Abstract

H4-1 is a planetary nebula (PN) located in the Galactic halo, and is notably carbon-rich and one of the most metal-deficient PNe in the Milky Way. To unveil its progenitor evolution through the accurate measurement of the gas mass, we conducted a comprehensive investigation of H4-1, using the newly obtained Seimei/KOOLS-IFU spectra and multiwavelength spectro-photometry data. The emission line images generated from the KOOLS-IFU datacube successfully resolve the ellipsoidal nebula and the equatorial flattened disk that are frequently seen in bipolar PNe evolved from massive progenitors. By a fully data-driven method, we directly derived the seven elemental abundances, the gas-to-dust mass ratio, and the gas and dust masses based on our own distance scale. By comparing the observed quantities with both the photoionization model and the binary nucleosynthesis model, we conclude that the progenitors of an initial mass of 1.87 Msun and 0.82 Msun are second generation stars formed ~4 Gyrs after the Big Bang, and underwent mass-transfers, binary merger, and ultimately evolved into a PN showing unique chemical abundances. Our binary model successfully reproduces the observed abundances and also explains evolutionary time scale of H4-1.