Recent Investigations on AA Doradus
Thomas Rauch (Institute for Astronomy, Astrophysics, Kepler Center, for Astro, Particle Physics, Eberhard Karls University, Tuebingen,, Germany)

TL;DR
This paper presents a new spectral analysis of AA Doradus using advanced non-LTE models, resolving previous discrepancies in surface gravity measurements and providing updated insights into the system's components.
Contribution
It introduces a state-of-the-art non-LTE spectral analysis that reconciles prior gravity discrepancies and refines the primary's rotational velocity in AA Doradus.
Findings
Resolved the gravity discrepancy with light-curve analysis
Measured the secondary's orbital velocity and mass range
Determined the primary's rotation at 65% of bound rotation
Abstract
AA Dor is an eclipsing, post common-envelope binary with an sdOB-type primary and an unseen low-mass secondary, believed to be a brown dwarf. Eleven years ago, a NLTE spectral analysis of the primary showed a discrepancy with the surface gravity that was derived by radial-velocity and light-curve analysis that could not be explained. Since then, emission lines of the secondary were identified in optical spectra and its orbital-velocity amplitude was measured. Thus, the masses of both components are known, however, within relatively large error ranges. The secondary's mass was found to be around the stellar hydrogen-burning mass limit and, thus, it may be a brown dwarf or a late M-type dwarf. In addition, a precise determination of the primary's rotational velocity showed recently, that it rotates at about 65% of bound rotation - much slower than previously assumed. A new spectral…
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Taxonomy
TopicsStellar, planetary, and galactic studies · Astronomy and Astrophysical Research · Astronomical Observations and Instrumentation
