The detection of heavy metals in the circumstellar envelopes of post-AGB stars

TL;DR

This paper identifies a new spectral peculiarity in post-AGB stars, revealing heavy metal enrichment in their circumstellar envelopes through line splitting and asymmetry analysis.

Contribution

It introduces the detection of line splitting and asymmetry as indicators of heavy metal presence and circumstellar structure in post-AGB stars.

Findings

Splitting of BaII lines indicates structured circumstellar envelopes.

Heavy metals are dredged up into the envelope during stellar evolution.

Line asymmetry correlates with envelope morphology and kinematics.

Abstract

A new type of peculiarity -- a splitting or asymmetry of strong absorption lines, is found in the optical spectra of selected post-AGB stars with C-rich circumstellar envelopes. The effect is maximal in BaII lines whose profile is split into two-three components. The particular components of the split absorption lines are shown to be formed in a structured circumstellar envelope, suggesting an efficient dredge-up of the heavy metals produced during the preceding evolution of this star into the envelope. We suspect that the splitting (or asymmetry) of the profiles of strongest absorptions with low excitation potential of the low level can be associated with the kinematic and chemical properties of the circumstellar environment and with type of its morphology.