Seismology of a Massive Pulsating Hydrogen Atmosphere White Dwarf

Pelisoli, Ingrid; Peçanha, Viviane; Costa, J. E. S.; Hermes, J. J.; Winget, D. E.; Castanheira, B. G.; Córsico, Alejandro H.; Romero, A. D.; Althaus, Leandro Gabriel; Kleinman, S. J.; Nitta, A.; Koester, D.; Külebi, Baybars; Jordan, S.; Kanaan, A.

doi:10.1088/0004-637x/757/2/177

Cited by 15 publications

(15 citation statements)

References 38 publications

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“…The periods listed in Table 5, are a combination of two sets of observations. The first set corresponds to those periods reported by Kepler et al (2012), who performed asteroseismological fits employing the model grid presented in Romero et al (2012) and Castanheira & Kepler (2008). The results from seismology by using the full evolutionary models following Romero et al (2012) are: M * = 0.88 ± 0.02M ⊙ , T eff = 12 100 ± 140 K, M H = (4.0 ± 3.3) × 10 −7 M * , M He = (2.6 ± 0.3) × 10 −3 M * , X C = 0.37 ± 0.01 and X O = 0.62 ± 0.01.…”

Section: Particular Casesmentioning

confidence: 99%

Asteroseismological Study of Massive Zz Ceti Stars With Fully Evolutionary Models

Romero

Kepler

Córsico

et al. 2013

ApJ

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116

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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 and the envelope. Our sample comprise all the ZZ Ceti stars with spectroscopic stellar masses between 0.72 and 1.05M ⊙ known to date. The asteroseismological analysis of a set of 42 stars gives the possibility to study the ensemble properties of the massive pulsating white dwarf stars with carbon−oxygen cores, in particular the thickness of the hydrogen envelope and the stellar mass. A significant fraction of stars in our sample have stellar mass high enough as to crystallize at the effective temperatures of the ZZ Ceti instability strip, which enables us to study the effects of crystallization on the pulsation properties of these stars. Our results show that the phase diagram presented in Horowitz et al. (2010) seems to be a good representation of the crystallization process inside white dwarf stars, in agreement with the results from white dwarf luminosity function in globular clusters.

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Section: Particular Casesmentioning

confidence: 99%

Asteroseismological Study of Massive Zz Ceti Stars With Fully Evolutionary Models

Romero

Kepler

Córsico

et al. 2013

ApJ

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116

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“…We have thus engaged in a search for pulsations in massive WDs in or near the DAV (or ZZ Ceti) instability strip, a region for which WDs with hydrogen-dominated atmospheres have the appropriate temperature to develop a hydrogen partial ionization zone, which in turn drives global pulsations. That search has already yielded multiple new massive DAVs (Kepler et al 2012;Castanheira et al 2013) after the Gianninas et al (2011), derive the atmosphere parameters and show this is a high-surface-gravity WD, with log g = 9.08 ± 0.06. This corresponds to a mass of 1.20 ± 0.03 M ⊙ .…”

Section: Introductionmentioning

confidence: 99%

Discovery of an Ultramassive Pulsating White Dwarf

Hermes¹,

Kepler²,

Castanheira³

et al. 2013

ApJ

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We announce the discovery of the most massive pulsating hydrogen-atmosphere 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 ± 0.06, which corresponds to a mass of 1.20 ± 0.03 M ⊙ . Stellar evolution models indicate that the progenitor of such a high-mass WD endured a stable carbonburning phase, producing an oxygen-neon-core WD. The discovery of pulsations in GD 518 thus offers the first opportunity to probe the interior of a WD with a possible oxygen-neon core. Such a massive WD should also be significantly crystallized at this temperature. The star exhibits multiperiodic luminosity variations at timescales ranging from roughly 425 − 595 s and amplitudes up to 0.7%, consistent in period and amplitude with the observed variability of typical ZZ Ceti stars, which exhibit non-radial g-mode pulsations driven by a hydrogen partial ionization zone. Successfully unraveling both the total mass and core composition of GD 518 provides a unique opportunity to investigate intermediate-mass stellar evolution, and can possibly place an upper limit to the mass of a carbon-oxygen-core WD, which in turn constrains Type Ia supernovae progenitor systems.

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“…Hence, the SDSS WD catalogs present an unprecedented opportunity to discover massive pulsating WDs and to eventually carry out rigorous tests of crystallization theory, which served as an impetus for this work. Mukadam et al (2004), Kepler et al (2005), Mullally et al (2005), Castanheira et al (2006), Castanheira & Kepler (2009), Kepler et al (2012), and Castanheira et al (2013) have used the SDSS data to search for DAVs, including massive ones. Currently, there 1 1 mma = 0.1% relative amplitude are about 200 DAVs known.…”

Section: Introductionmentioning

confidence: 99%

Four new massive pulsating white dwarfs including an ultramassive DAV

Curd

Gianninas

Bell

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We report the discovery of four massive (M > 0.8 M ) ZZ Ceti white dwarfs, including an ultramassive 1.16 M star. We obtained ground based, time-series photometry for thirteen white dwarfs from the Sloan Digital Sky Survey Data Release 7 and Data Release 10 whose atmospheric parameters place them within the ZZ Ceti instability strip. We detect mono-periodic pulsations in three of our targets (J1053, J1554, and J2038) and identify three periods of pulsation in J0840 (173, 327, and 797 s). Fourier analysis of the remaining nine objects do not indicate variability above the 4 A detection threshold. Our preliminary asteroseismic analysis of J0840 yields a stellar mass M = 1.14 ± 0.01 M , hydrogen and helium envelope masses of M H = 5.8 × 10 −7 M and M He = 4.5 × 10 −4 M , and an expected core crystallized mass ratio of 50-70%. J1053, J1554, and J2038 have masses in the range 0.84 − 0.91M and are expected to have a CO core; however, the core of J0840 could consist of highly crystallized CO or ONeMg given its high mass. These newly discovered massive pulsators represent a significant increase in the number of known ZZ Ceti white dwarfs with mass M > 0.85 M , and detailed asteroseismic modeling of J0840 will allow for significant tests of crystallization theory in CO and ONeMg core white dwarfs.

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Seismology of a Massive Pulsating Hydrogen Atmosphere White Dwarf

Cited by 15 publications

References 38 publications

Asteroseismological Study of Massive Zz Ceti Stars With Fully Evolutionary Models

Asteroseismological Study of Massive Zz Ceti Stars With Fully Evolutionary Models

Discovery of an Ultramassive Pulsating White Dwarf

Four new massive pulsating white dwarfs including an ultramassive DAV

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