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We extend our previous pulsational stability analyses of PG 1159 stars by modeling the hybrid PG 1159 type star Abell 43. We show that the standard kappa-mechanism due to the ionization of C and O in the envelope of this H-rich PG 1159 star…

Astrophysics · Physics 2009-11-11 P. -O. Quirion , G. Fontaine , P. Brassard

We employ a state-of-the-art asteroseismological model of G117-B15A, the archetype of the H-rich atmosphere (DA) white dwarf pulsators (also known as DAV or ZZ Ceti variables), and use the most recently measured value of the rate of period…

The {\emph{Kepler}} space telescope has provided exquisite data to perform asteroseismic analysis on evolved star ensembles. Studying star clusters offers significant insight into stellar evolution and structure, due to having a large…

Solar and Stellar Astrophysics · Physics 2021-08-03 Zeynep Çelik Orhan

(Abridged) We aim at measuring the near-infrared photometry, and deriving the mass, age, temperature, and surface gravity of WISE J085510.74-071442.5 (J0855-0714), which is the coolest known object beyond the Solar System as of today. We…

Earth and Planetary Astrophysics · Physics 2016-08-03 M. R. Zapatero Osorio , N. Lodieu , V. J. S. Béjar , E. L. Martín , V. D. Ivanov , A. Bayo , H. M. J. Boffin , K. Mužić , D. Minniti , J. C. Beamín

This article discusses the physical and kinematical characteristics of planetary nebulae accompanying PG1159 central stars. The study is based on the parallax and proper motion measurements recently offered by Gaia space mission. Two…

Solar and Stellar Astrophysics · Physics 2021-08-18 A. Ali , Wedad R. Alharbi

The X-ray source eRASSU J065715.3+260428 was identified as a likely thermally emitting isolated neutron star in a search in the SRG/eROSITA All-Sky Survey. We investigated the nature and evolutionary state of the source through a dedicated…

High Energy Astrophysical Phenomena · Physics 2025-01-14 J. Kurpas , A. M. Pires , A. D. Schwope , Z. C. Pan , Z. L. Zhang , L. Qian , F. Haberl , L. Ji , I. Traulsen

We report on Keck and {\em Hubble Space Telescope} observations of the binary millisecond pulsar PSR B1855+09. We detect its white-dwarf companion and measure $\mv=25.90\pm0.12$ and $\mi=24.19\pm0.11$ (Vega system). From the…

Astrophysics · Physics 2009-10-31 M. H. van Kerkwijk , J. F. Bell , V. M. Kaspi , S. R. Kulkarni

The pulsating DA white dwarfs (ZZ Ceti stars) are $g$-mode non-radial pulsators. Asteroseismology provides strong constraints on their global parameters and internal structure. Since all the DA white dwarfs falling in the ZZ Ceti…

Pulsating white dwarf stars can be used as astrophysical laboratories to constrain the properties of weakly interacting particles. Comparing the cooling rates of these stars with the expected values from theoretical models allows us to…

Solar and Stellar Astrophysics · Physics 2015-06-22 Alejandro H. Córsico , Leandro G. Althaus , Marcelo M. Miller Bertolami , S. O. Kepler , Enrique García-Berro

Gravito-inertial asteroseismology saw its birth from the 4-years long light curves of rotating main-sequence stars assembled by the Kepler space telescope. High-precision measurements of internal rotation and mixing are available for about…

Solar and Stellar Astrophysics · Physics 2024-10-10 Joey S. G. Mombarg , Conny Aerts , Timothy Van Reeth , Daniel Hey

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…

Solar and Stellar Astrophysics · Physics 2020-10-27 Alejandro H. Córsico , Alejandra D. Romero , Leandro G. Althaus , Marcelo M. Miller Bertolami

We present new results of a stability analysis of realistic models of post-extreme horizontal branch stars. We find that g-mode instabilities develop in some of these models as a result of a potent epsilon-mechanism associated with the…

Astrophysics · Physics 2009-10-30 S. Charpinet , G. Fontaine , P. Brassard , B. Dorman

We derive the basic physical parameters of the field double-mode RR Lyrae star BS Com from its observed periods and the requirement of consistency between the pulsational and evolutionary constraints. By using the current solar-scaled…

Astrophysics · Physics 2009-11-13 I. Dekany , G. Kovacs , J. Jurcsik , R. Szabo , M. Varadi , A. Sodor , K. Posztobanyi , Zs. Hurta , K. Vida , N. Vityi , A. Szing

Observations conducted with the Fine Guidance Sensor on Hubble Space Telescope (HST) providing high cadence and precision time-series photometry were obtained over 10 consecutive days in December 2008 on the host star of the transiting…

Context. gamma Doradus (gamma Dor) are late A and F-type stars pulsating with high order gravity modes (g-modes). The existence of different evolutionary phases crossing the gamma Dor instability strip raises the question of the existence…

Solar and Stellar Astrophysics · Physics 2015-05-27 M. -P. Bouabid , J. Montalban , A. Miglio , M. -A. Dupret , A. Grigahcene , A. Noels

With [Fe/H] = -3.5, CS 30322-023 is the most metal-poor star to exhibit a clear s-process signature and the most metal-poor ``lead star'' known. CS 30322-023 is also remarkable in having the lowest surface gravity (log g <= -0.3) among the…

Astrophysics · Physics 2009-11-11 T. Masseron , S. Van Eck , B. Famaey , S. Goriely , B. Plez , L. Siess , T. C. Beers , F. Primas , A. Jorissen

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 have found that the white dwarf PG 1101+364 is a double-lined white dwarf/white dwarf binary with an orbital period of 3.47 hours. PG 1101+364 is the shortest period detached double-degenerate yet found and gravitational radiation will…

Astrophysics · Physics 2016-06-08 T. R. Marsh

In this work, we aim to estimate the stellar parameters of the primary (Aa) by performing asteroseismic analysis on its period-spacing pattern. We use the C-3PO neural network to perform asteroseismic modelling of the g-mode period-spacing…

G\,29$-$38 (TIC~422526868) is one of the brightest ($V=13.1$) and closest ($d = 17.51$\,pc) pulsating white dwarfs with a hydrogen-rich atmosphere (DAV/ZZ Ceti class). It was observed by the {\sl TESS} spacecraft in sectors 42 and 56. The…