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arXiv · 2405.14269

The time-variable ultraviolet sky: Active Galactic Nuclei, Stars and White Dwarfs

Rolf Buehler·Julian Schliwinski
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Abstract

Here, we present the 1UVA catalog of time variable ultraviolet (UV) sources. We describe a new analysis pipeline, the VAriable Source Clustering Analysis (VASCA). We apply the pipeline to 10 years of data from the GALaxy Evolution eXplorer (GALEX) satellite. We analyse a sky area of 302 deg$^2$ , resulting in the detection of 4202 time-variable UV sources. We cross correlate these sources with multi-frequency data from the Gaia satellite and the SIMBAD database, finding an association for 3655 sources. The source sample is dominated by Active Galactic Nuclei ($\approx$73 %) and stars ($\approx$24 %). We look at UV and multi-frequency properties of these sources, focusing on the stellar population. We find UV variability for four White Dwarfs. One of them, WD J004917.14-252556.81, has recently been found to be the most massive pulsating White Dwarf. Its Spectral Energy Distribution shows no sign of a stellar companion. The observed flux variability is unexpected and difficult to explain.

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Rolf Buehler, Julian Schliwinski. 2024-05-23. The time-variable ultraviolet sky: Active Galactic Nuclei, Stars and White Dwarfs. https://doi.org/10.1051/0004-6361%2F202449973

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