Searching for ZZ Ceti White Dwarfs in the Gaia Survey

Abstract

The {\it Gaia} satellite recently released parallax measurements for $\sim$260,000 high-confidence white dwarf candidates, allowing for precise measurements of their physical parameters. By combining these parallaxes with Pan-STARRS and $u$-band photometry, we measured the effective temperature and stellar mass for all white dwarfs in the Northern Hemisphere within 100 parsecs of the Sun, and identified a sample of ZZ Ceti white dwarf candidates within the so-called instability strip. We acquired high-speed photometric observations for 90 candidates using the PESTO camera attached to the 1.6-m telescope at the Mont-Mégantic Observatory. We report the discovery of 38 new ZZ Ceti stars, including two very rare ultra-massive pulsators. We also identified 5 possibly variable stars within the strip, in addition to 47 objects that do not appear to show any photometric variability. However, several of those could be variable with an amplitude below our detection threshold, or could be located outside the instability strip due to errors in their photometric parameters. In the light of our results, we explore the trends of the dominant period and amplitude in the $M-T_{\mathrm{eff}}$ plane, and briefly discuss the question of the purity of the ZZ Ceti instability strip (i.e. a region devoid of non-variable stars).

39 pages, 10 figures. Accepted for publication in The Astronomical Journal

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• White dwarfs as Physics laboratories: lights and shadows
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• On The Impact Of 22Ne On The Pulsation Periods Of Carbon-Oxygen White Dwarfs With Helium Dominated Atmospheres
• Pulsating H-deficient WDs and pre-WDs observed with TESS: V. Discovery of two new DBV pulsators, WD J152738.4-450207.4 and WD 1708-871, and asteroseismology of the already known DBV stars PG 1351+489, EC 20058-5234, and EC 04207-4748
• The Pulsating Helium-Atmosphere White Dwarfs I: New DBVs from the Sloan Digital Sky Survey
• Asteroseismology of PG 1541$+$651 and BPM 31594 with TESS
• General relativistic pulsations of ultra-massive ZZ Ceti stars
• Seismology and diffusion of ultramassive white dwarf magnetic fields
• Seismic test of the mass-radius relationship of hydrogen-atmospheric white dwarf stars
• Inactive longitude and superflare in the active single-lined pre-main sequence binary V2279 Cyg
• J-PLUS: Understanding outlier white dwarfs in the third data release via dimensionality reduction