A window on the efficiency of the s-process in AGB stars: chemical abundances of n-capture elements in the planetary nebula NGC 3918

TL;DR

This study uses deep high-resolution spectrophotometry of the planetary nebula NGC 3918 to measure neutron-capture element abundances, providing new insights into the s-process efficiency in AGB star progenitors.

Contribution

It presents the deepest spectra of a planetary nebula with precise measurements of faint n-capture element lines, advancing understanding of stellar nucleosynthesis.

Findings

Detection of faint lines of Se, Kr, Rb, Xe

Accurate chemical abundances of neutron-capture elements

Constraints on s-process efficiency in progenitor star

Abstract

The chemical content of the planetary nebula NGC 3918 is investigated through deep, high-resolution (R~40000) UVES at VLT spectrophotometric data. We identify and measure more than 750 emission lines, making ours one of the deepest spectra ever taken for a planetary nebula. Among these lines we detect very faint lines of several neutron-capture elements (Se, Kr, Rb, and Xe), which enable us to compute their chemical abundances with unprecedented accuracy, thus constraining the efficiency of the s-process and convective dredge-up in the progenitor star of NGC 3918.