Observing bright pulsating white dwarfs with PLATO: A new window into the late stages of stellar evolution

TL;DR

This work argues that the ESA PLATO mission, via its Complementary Science program, can dramatically advance white dwarf asteroseismology by providing two years of continuous, high-precision photometry for bright WDs across DA, DB, and H-deficient classes. The authors assemble a representative sample of ~650 WD candidates in PLATO's Southern LOPS2 field, derive atmospheric parameters from multi-band photometry, and identify 23 ZZ Ceti and 35 DBV candidates for intensive asteroseismic study. Simulations with PlatoSim indicate that PLATO can detect pulsation modes down to amplitudes of about $0.1$ mma for favorable observing configurations, enabling robust mode identification and internal-structure constraints, including core crystallization and envelope stratification, while synergizing with Gaia and TESS data. These efforts will yield unprecedented insights into WD origins, late-stage evolution, internal physics, and planetary-system fates, especially when combined with targeted spectroscopy and complementary time-domain surveys.

Abstract

We present the scientific case for exploiting the capabilities of the PLATO mission to study bright pulsating white dwarfs across a wide spectral range, including hydrogen-deficient types (GW Vir and DBV stars) and hydrogen-rich classes (classical DAVs, pulsating extremely low-mass DA white dwarfs, and ultra-massive DA white dwarfs). PLATOs exceptional photometric precision, long-duration continuous monitoring, and extensive sky coverage promise transformative advances in white dwarf asteroseismology. Our key objectives include probing the internal structure and chemical stratification of white dwarfs, detecting secular changes in pulsation modes over extended timescales, and discovering rare or previously unknown classes of pulsators. To assess feasibility, we constructed a sample of 650 white dwarf candidates identified within PLATOs Southern LOPS2 field using the PLATO complementary science catalogue combined with Gaia DR3, and derived atmospheric parameters through photometric modeling. This sample comprises 118 DA white dwarfs (including 23 ZZ Ceti candidates), and 41 non-DAs (including 35 DBV candidates). Simulated observations using PlatoSim demonstrate that PLATO will be capable of detecting white dwarf pulsation modes with amplitudes as low as 0.1 mma depending on stellar magnitude, observation duration, pixel location, and the number of contributing cameras. We provide detailed detection limits and visibility forecasts for known pulsators across a representative range of these parameters. Furthermore, we emphasize strong synergies with Gaia astrometry, TESS photometry, and targeted spectroscopic campaigns, which together will enable robust mode identification and detailed stellar modeling. Collectively, these efforts will unlock unprecedented insights into white dwarf origins, evolution and internal physics, and the fate of their planetary systems.

Figures (9)

• Figure 1: H-R diagram of white dwarf candidates identified in the PLATO-CS input catalog 2025AA...694A.185J. The color bar indicates the WD probability from 2021MNRAS.508.3877G. Extremely low-mass (ELM) WD candidates, selected from the PLATO-CS catalog and cross-matched with the sample of 2019MNRAS.488.2892P, are shown in red.
• Figure 2: Model fits to the DA white dwarf WDJ053306.78$-$560353.38 (HE 0532$-$5605), which is a previously known ZZ Ceti pulsator in the PLATO field. The top panel shows the best-fitting pure H (filled dots) and pure He (open circles) atmosphere white dwarf models to the Skymapper photometry (error bars). This panel also includes the name and the Gaia Source ID, and the photometry used in the fitting. The middle panel shows the predicted spectrum (red line) based on the pure-H solution, overplotted on the observed spectrum (black line). The bottom panel presents the same comparison over a broader wavelength range.
• Figure 3: Masses and effective temperatures for the PLATO WD sample assuming pure H atmospheres (open circles). The blue and red lines show the empirical boundaries of the ZZ Ceti instability strip from vincent20. Blue dots mark the three known ZZ Ceti stars in the sample, whereas the green dots mark the DAV candidates that fall near or within the instability strip and also have photometric spectral energy distributions consistent with DA white dwarfs.
• Figure 4: Location of the PLATO white dwarf sample in the effective temperature–surface gravity plane, modeled under the assumption of He-rich atmospheres. The blue and red dashed lines indicate the extended empirical boundaries of the DB instability strip based on 2019AARv..27....7C2022ApJ...927..158V. Blue points highlight stars located within or close to the strip. The known DBV WDJ052330.80−472219.55 is marked with a red dot.
• Figure 5: The first PLATO pointing field in the South, LOPS2, shown in equatorial coordinates. The increasing darker shade of blue illustrates the N-CAM overlap of $n_{\rm CAM} \in \{6, 12, 18, 24\}$, respectively. The color coded circles (according to the PLATO N-CAM passband magnitude, $P$) shows the WD candidates from Fig. \ref{['fig:cmd_WD']}, while the pink circles show the 20 WD stars from the PLATO-CS catalogue used for simulations in this paper. This figure has been adapted from 2025AA...694A.185J.