Asteroseismology study of a new faint ZZ Ceti J053009.62+594557.0 discovered in WFST

TL;DR

The paper analyzes WFST J053009.62+594557.0, a faint ZZ Ceti discovered by WFST, using two nights of g-band photometry to extract three pulsation periods. Through asteroseismic modeling with the White Dwarf Evolution Code, the authors derive a best-fit interior model with $T_eff \,\approx\ 11{,}850$ K and $M \,\approx\ 0.60\ M_sun$, consistent with Gaia parallax, XP spectrum, CMD, and SED constraints. The pulsation modes are identified as two $l=1$ and one $l=2$, and the asteroseismic distance matches Gaia within $\approx 1.5\%$, validating the model. The study highlights cross-validation across independent datasets and discusses evolutionary history and how WFST J0530 fits within the DAV population, offering insights into thin envelope structure and core composition.

Abstract

In this work, we present a detailed asteroseismological analysis of WFST J053009.62+594557.0, a newly discovered faint pulsating white dwarf by the Wide Field Survey Telescope (WFST) with a Gaia G magnitude of 19.13. Analysis of two nights of high-precision WFST g band photometry reveals three significant pulsation frequencies with high signal-to-noise ratios. Follow-up P200/DBSP spectroscopy classifies the object as a DA white dwarf with Teff=11,609 $\pm$ 605 K and M = 0.63$\pm$ 0.22 $M_{\odot}$. To probe its internal structure, we construct asteroseismological models with the White Dwarf Evolution Code (WDEC). After exploring sufficient matching models, best-fitting solutions yield Teff=11,850$\pm$ 10 K and M = 0.600 $\pm$ 0.005 $M_{\odot}$, consistent with independent constraints from Gaia color-magnitude diagram, Gaia XP spectrum, P200 spectral fitting, SED fitting, and Gaia parallax. It has shown that the asteroseismological distance agrees with the Gaia parallax to 1.45\%.

Figures (13)

• Figure 1: WFST $g$-band light curve for WFST J0523, obtained on 2023 September 18.
• Figure 2: The cut-outs of normalized Balmer lines from P200/DBSP spectrum of WFST J0530. From bottom to top, black lines are the H$\alpha$, H$\beta$, H$\gamma$, and H$\delta$ lines, while the red dashed lines display the best-fitting model.
• Figure 3: The Lomb–Scargle periodogram of WFST J0530. The horizontal red dashed line indicates the position where $SNR$ = 4.
• Figure 4: Three-dimensional color graph of function $\chi^2$ versus mass and $T_{\rm eff}$.
• Figure 5: Three-dimensional color graph of function $\chi^2$ versus -log($M_{\rm He}/M_{\rm *}$) and -log($M_{\rm H}/M_{\rm *}$).