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arXiv · 2609.25216

The white dwarf binary pathways survey - XI. The Gaia-GALEX UV Excess Sample for systems within 350 pc

James A. Garbutt·S. G. Parsons·N. Gentile Fusillo·B. T. Gänsicke·M. S. Hernandez·F. Lagos-Vilches·R. Raddi·A. Rebassa-Mansergas·J. J. Ren·M. R. Schreiber·O. Toloza·M. Zorotovic
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Abstract

White dwarfs (WDs) with F, G or K type binary companions are the last common ancestor to a zoo of exotic phenomena. Finding a clean sample of such systems is difficult, as WDs in such binaries are usually outshone at optical wavelengths by their non-degenerate companion. It is useful to have a sample of such binaries - they can be studied to investigate binary evolution, as they may have undergone a previous phase of mass transfer. Using Gaia data release 3 and GALEX, we compile a sample of 2597 candidate WD + FGK systems within 350 pc. These were identified via their ultraviolet excesses relative to MESA Isochrones and Stellar Tracks (MIST) model predictions consistent with the Gaia parameters of their non-degenerate companions. We estimate the mass, surface gravity and effective temperature of the WDs by fitting the excess ultraviolet flux to models, or through interpolation where only one ultraviolet band was available. We also estimate the age of the system where possible, by comparing against any wide WD companions in higher-order stellar systems, or by checking if the system is a member of a cluster. On comparing against Simbad, we estimate the level of contamination within our sample to be between 10-35 per cent. This is a valuable sample for investigating WD + FGK binaries, particularly those containing hotter WDs (Teff,WD >~ 25 kK), and systems with post-main sequence companions.

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James A. Garbutt, S. G. Parsons, N. Gentile Fusillo, B. T. Gänsicke, M. S. Hernandez, F. Lagos-Vilches, R. Raddi, A. Rebassa-Mansergas, J. J. Ren, M. R. Schreiber, O. Toloza, M. Zorotovic. 2026-09-21. The white dwarf binary pathways survey - XI. The Gaia-GALEX UV Excess Sample for systems within 350 pc. https://arxiv.org/abs/2609.25216

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