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arXiv · 2610.38798

Rotation and outburst-like brightenings in ZZ Ceti stars observed by TESS

Zs. Bognár·Á. Sódor
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Abstract

Context. Pulsating white dwarfs, such as ZZ Ceti stars, allow for the study of white dwarf rotation through rotationally split pulsation modes. Space-based photometry has also revealed outbursts in some cool ZZ Ceti stars. Aims. We extend the search for rotationally split pulsation multiplets and outburst-like brightenings among known ZZ Ceti stars observed by TESS. We check whether the TESS data add new evidence for a connection between outburst activity and stellar rotation. Methods. We analysed 120 s and 20 s cadence TESS light curves available up to Sector 96. After light curve correction and quality filtering, we performed iterative frequency analysis. Candidate rotationally split multiplets were identified automatically and visually validated. Outburst candidates were selected from smoothed flux excursions, followed by light curve inspection and pixel-level TESS diagnostics. Results. We identify 11 ZZ Ceti stars with accepted triplet candidates and derive rotation periods of about 8-94 h; three triplet detections are reported here for the first time. The targets are broadly consistent with the dispersion of rotation periods found in previous studies. The time-domain search produced 19 outburst-like events in 11 stars after light curve inspection. Pixel-level diagnostics indicate that most are likely caused by foreground asteroid contamination. We identify three stars (TIC 219442838, TIC 307908863, and TIC 630426257) as candidate stellar outbursters. None belong to the accepted triplet-rotation sample.

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Zs. Bognár, Á. Sódor. 2026-10-28. Rotation and outburst-like brightenings in ZZ Ceti stars observed by TESS. https://arxiv.org/abs/2610.38798

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