The optically bright post-AGB population of the LMC

TL;DR

This study identifies and characterizes 105 post-AGB star candidates in the LMC, providing a valuable dataset for testing stellar evolution theories, especially regarding binary systems and circumstellar environments.

Contribution

It presents a new catalogue of LMC post-AGB candidates with fundamental properties, including spectral classifications and SED analysis, enhancing understanding of late stellar evolution.

Findings

Approximately half show disc-like SEDs, suggesting binary evolution involvement.

The catalogue includes 70 high-probability post-AGB stars and 1337 candidates.

Data supports the link between disc sources and binary systems in post-AGB evolution.

Abstract

The detected variety in chemistry and circumstellar shell morphology of the limited sample of Galactic post-AGB stars is so large that there is no consensus yet on how the different objects are linked by evolutionary channels. The evaluation is complicated by the fact that their distances and hence luminosities remain largely unknown. Via cross-correlation of the Spitzer SAGE catalogue with optical catalogues we selected a sample of LMC post-AGB candidates based on their [8]-[24] colour index and estimated luminosity. We determined the fundamental properties of the central stars of 105 of these objects using low-resolution, optical spectra that we obtained at Siding Spring Observatory and SAAO, and constructed a catalogue of 70 high probability and 1337 candidate post-AGB stars that is available at the CDS. The sample forms an ideal testbed for stellar evolution theory predictions of the final phase of low- and intermediate-mass stars, because the distance and hence luminosity and also the current and initial mass of these objects is well constrained. About half of the objects in our sample of post-AGB candidates show a spectral energy distribution (SED) that is indicative of a disc rather than an expanding and cooling AGB remnant. Like in the Galaxy, the disc sources are likely associated with binary evolution. Important side products of this research are catalogues of candidate young stellar objects, candidate supergiants with circumstellar dust, and discarded objects for which a spectrum was obtained. These too are available at the CDS.