Related papers: Four New Massive Pulsating White Dwarfs Including …

We present time-series photometry of 31 massive DA white dwarfs with $M\gtrsim 0.9~M_\odot$ within the ZZ Ceti instability strip from the Montreal White Dwarf Database 100 pc sample. The majority of the targets had no previous time-series…

The discovery of pulsations in ultra-massive white dwarfs can help to probe their interiors and unveil their core composition and crystallized mass fraction through asteroseismic techniques. To date, the richest pulsating ultra-massive…

We report the discovery of the second and third pulsating extremely low mass white dwarfs (WDs), SDSS J111215.82+111745.0 (hereafter J1112) and SDSS J151826.68+065813.2 (hereafter J1518). Both have masses < 0.25 Msun and effective…

We present extensive follow-up time-series photometry of WD J0049$-$2525, the most massive pulsating white dwarf currently known with $T_{\rm eff} = 13\, 020\,{\rm K}$ and $\log{\it g} = 9.34$ cm s$^{-2}$. The discovery observations…

We present APO and Gemini time-series photometry of WD J004917.14$-$252556.81, an ultramassive DA white dwarf with $T_{\rm eff} = 13020$ K and $\log{g} = 9.34$. We detect variability at two significant frequencies, making J0049$-$2525 the…

Measuring g-mode pulsations of isolated white dwarfs can reveal their interior properties to high precision. With a spectroscopic mass of ~0.51 M_{\odot} (log g = 7.82), the DAV white dwarf HS 1824+6000 is near the transition between…

We report the discovery of the first pulsating extremely low mass (ELM) white dwarf (WD), SDSS J184037.78+642312.3 (hereafter J1840). This DA (hydrogen-atmosphere) WD is by far the coolest and the lowest-mass pulsating WD, with Teff = 9100…

We announce the discovery of the most massive pulsating hydrogen-atmosphere (DA) white dwarf (WD) ever discovered, GD 518. Model atmosphere fits to the optical spectrum of this star show it is a 12,030 +/- 210 K WD with a log(g) = 9.08 +/-…

The internal structures of pulsating white dwarfs can be explored only with asteroseismology. Time series photometric observations were made for the pulsating DA white dwarf (ZZ Ceti star) WD~0246+326 during 9 nights in 2014 with a bi-site…

We present the first asteroseismological study for 42 massive ZZ Ceti stars based on a large set of fully evolutionary carbon$-$oxygen core DA white dwarf models characterized by a detailed and consistent chemical inner profile for the core…

We report the discovery of two new ZZ Ceti pulsators, LP 133-144 and HE 1258+0123, selected on the basis of model atmosphere fits to optical spectroscopic data. The atmospheric parameters for LP 133-144, Teff = 11,800 +/- 200 K and log g =…

We report the discovery of two new pulsating extremely low-mass (ELM) white dwarfs (WDs), SDSS J161431.28+191219.4 (hereafter J1614) and SDSS J222859.93+362359.6 (hereafter J2228). Both WDs have masses <0.25 Msun and thus likely harbor…

As part of an ongoing program to map better the empirical instability strip of pulsating ZZ Ceti white dwarfs, we present a brief progress report based on our last observing season. We discuss here high-speed photometric measurements for 6…

Ultra-massive hydrogen-rich (DA) white dwarfs (WD) are expected to have a substantial portion of their cores in a crystalline state at the effective temperatures characterizing the ZZ Ceti instability strip, as a result of Coulomb…

In recent years, approximately 150 low-mass white dwarfs (WDs), typically with masses below 0.4 solar masses, have been discovered. Observational evidence indicates that most of these low-mass WDs are found in binary systems, supporting…

We aimed at collecting all known white dwarf pulsators with hydrogen-dominated atmospheres and list their main photometric and atmospheric parameters together with their pulsation periods and amplitudes observed at different epochs. For…

Asteroseismology of DAV stars (ZZ Ceti variables) can provide valuable clues about the origin, structure and evolution of DA (atmospheres rich in H) white dwarfs. Recently, a new DAV star, WD J191643.83+393849.7, has been discovered in the…

We report the discovery of 42 white dwarfs in the original Kepler mission field, including nine new confirmed pulsating hydrogen-atmosphere white dwarfs (ZZ Ceti stars). Guided by the Kepler-INT Survey (KIS), we selected white dwarf…

We present our results on the continuation of our survey searching for new ZZ Ceti stars, inspired by the recently launched TESS space mission. The seven targets were bright DA-type white dwarfs located close to the empirical ZZ Ceti…

We present optical high-speed photometry of three millisecond pulsars with low-mass ($< 0.3 M_{\odot}$) white dwarf companions, bringing the total number of such systems with follow-up time-series photometry to five. We confirm the…