# Heavy-metal enrichment in the intermediate He-sdOB pulsator Feige 46

## TL;DR

This study reveals that the He-sdOB pulsator Feige 46 exhibits extreme overabundances of heavy metals, similar to the prototype LS IV-14116, indicating a shared chemical peculiarity among this pulsating star class.

## Contribution

It provides the first detailed abundance analysis of Feige 46, confirming its heavy-metal enrichment and chemical similarity to LS IV-14116, expanding understanding of chemical peculiarities in pulsating subdwarfs.

## Key findings

- Feige 46 has over 10,000 times solar abundance of yttrium and zirconium.
- Feige 46 shows heavy-metal enrichment similar to LS IV-14116.
- Feige 46 is confirmed as a heavy-metal subdwarf with peculiar chemical composition.

## Abstract

The intermediate He-enriched hot subdwarf star Feige 46 was recently reported as the second member of the V366 Aqr (or He-sdOBV) pulsating class. Feige 46 is very similar to the prototype of the class, LS IV$-$14116, not only in terms of pulsational properties, but also in terms of atmospheric parameters and kinematic properties. LS IV$-$14116 is additionally characterized by a very peculiar chemical composition, with extreme overabundances of the trans-iron elements Ge, Sr, Y, and Zr. In this paper, we investigate the possibility that the similitude between both pulsators extends to their chemical composition. We retrieved archived optical and UV spectroscopic observations of Feige 46 and perform an abundance analysis using model atmospheres and synthetic spectra computed with TLUSTY and SYNSPEC. In total, we derive abundances for 16 metallic elements and provide upper limits for four additional elements. From absorption lines in the optical spectrum of the star we measure an enrichment of more than 10 000$\times$ solar for yttrium and zirconium. As for strontium, the UV spectrum revealed it to be equally enriched. Our results confirm that Feige 46 is not only a member of the now growing group of "heavy-metal" subdwarfs, but also has an abundance pattern remarkably similar to that of LS IV$-$14116.