Atomic Gas in Debris Discs

TL;DR

This study searched for optical absorption lines in 16 debris disc stars, finding circumstellar gas evidence in one case, HD110058, which aligns with recent molecular gas detection and resembles the Beta Pictoris system.

Contribution

First optical absorption line survey of debris disc stars, identifying circumstellar gas in HD110058, linking optical and ALMA molecular gas observations.

Findings

No emission line activity detected in the sample.

Narrow absorption features found in four stars, with HD110058 showing strong circumstellar gas evidence.

HD110058's gas characteristics are similar to Beta Pictoris, supporting its debris disc nature.

Abstract

We have conducted a search for optical circumstellar absorption lines in the spectra of 16 debris disc host stars. None of the stars in our sample showed signs of emission line activity in either H$_{\alpha}$, Ca II or Na I, confirming their more evolved nature. Four stars were found to exhibit narrow absorption features near the cores of the photospheric Ca II and Na I D lines (when Na I D data were available). We analyse the characteristics of these spectral features to determine whether they are of circumstellar or interstellar origins. The strongest evidence for circumstellar gas is seen in the spectrum of HD110058, which is known to host a debris disc observed close to edge-on. This is consistent with a recent ALMA detection of molecular gas in this debris disc, which shows many similarities to the $\beta$ Pictoris system.