Chemical composition of A--F type post-AGB candidates

TL;DR

This study analyzes the chemical compositions of nine post-AGB candidate stars, revealing dust-gas separation effects and nitrogen enrichment, and compares observed abundance ratios with evolutionary models including rotation-induced mixing.

Contribution

First detailed abundance analysis of nine post-AGB candidates, identifying dust-gas separation and nitrogen enrichment, and comparing results with stellar evolution models.

Findings

Dust-gas separation observed in several stars.

Nitrogen enrichment found in multiple candidates.

Comparison with models suggests rotation-induced mixing effects.

Abstract

An abundance analysis has been conducted for a sample of nine post-AGB candidate stars; eight of them have not been explored before. We find four very promising objects like HD 105262, HD 53300 and CpD$-62^o5428$ among them. We find strong evidence of dust-gas separation through selective depletion of refractive elements in HD 105262. The same effect is also observed in HD 53300, CpD$-62^o5428$ and HD 114855 although abundance peculiarities are relatively smaller for the last two stars. We find strong enrichment of nitrogen for HD 725, HD 842, HD 1457, HD 9233 and HD 61227 but no further evidence to support their post-AGB nature. We have compared the observed [N/C] ratios of these stars with the predictions of evolutionary models which include the rotation induced mixing.