Whole Earth Telescope observations of BPM 37093: A seismological test of crystallization theory in white dwarfs

Kanaan, A.; Nitta, A.; Winget, D. E.; Kepler, S. O.; Montgomery, M. H.; Metcalfe, T. S.; Oliveira, Heitor O. de; Fraga, L.; Costa, A. F. Murillo; Costa, J. E. S.; Castanheira, B. G.; Giovannini, O.; Nather, R. E.; Mukadam, Anjum S.; Kawaler, S. D.; O'Brien, M. S.; Reed, M. D.; Kleinman, S. J.; Provençal, J. L.; Watson, T. K.; Kilkenny, D.; Sullivan, D. J.; Sullivan, T.; Shobbrook, B.; Jiang, Xiaojun; Ashoka, B. N.; Seetha, S.; Leibowitz, E. M.; Ibbetson, P.; Mendelson, Haim; Meistas, E.; Kalytis, R.; Ališauskas, D.; O’Donoghue, D.; Buckley, D. A. H.; Martinez, Peter; Wyk, F. van; Stobie, R. S.; Marang, F.; Zyl, L. van; Ogłoza, W.; Krzesinski, J.; Zoła, S.; Moskalik, P.; Breger, M.; Stankov, A.; Silvotti, R.; Piccioni, A.; Vauclair, G.; Dolez, N.; Chevreton, M.; Deetjen, J. L.; Dreizler, S.; Schuh, S.; Pérez, J. M. González; Østensen, R. H.; Ulla, A.; Manteiga, M.; Suárez, Olga; Burleigh, M. R.; Barstow, M. A.

doi:10.1051/0004-6361:20041125

Cited by 64 publications

(63 citation statements)

References 28 publications

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“…This number is the sum of all the modes observed during various observing seasons. References: 1) Kepler et al (1995); 2) Bradley (1993Bradley ( , 2001; 3) Bradley (1998); 4) Bergeron et al (1993), Bradley (2001); 5) Kleinman et al (1998); 6) Robinson et al (1995), Bradley (1998); 7) Pfeiffer et al (1996); 8) Kanaan et al (2005), Metcalfe et al (2004), but see also Fontaine & Brassard (2004).…”

Section: Introductionmentioning

confidence: 99%

Whole Earth telescope observations of the ZZ Ceti star HL Tau 76

Dolez

Vauclair²,

Kleinman³

et al. 2006

A&A

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This paper analyses the Whole Earth Telescope observations of HL Tau 76, the first discovered pulsating DA white dwarf. The star was observed during two Whole Earth Telescope campaigns. It was a second priority target during the XCOV13 campaign in 1996 and the first priority one during the XCOV18 campaign in 1999. The 1999 campaign reached 66.5% duty cycle. With a total duration of 18 days, the frequency resolution achieved is 0.68 µHz. With such a frequency resolution, we were able to find as many as 78 significant frequencies in the power spectrum, of which 34 are independent frequencies after removal of all linear combinations. In taking into account other frequencies present during the 1996 WET campaign and those present in earlier data, which do not show up in the 1999 data set, we find a total of 43 independent frequencies. This makes HL Tau 76 the richest ZZ Ceti star in terms of number of observed pulsation modes. We use those pulsation frequencies to determine as much as possible of the internal structure of HL Tau 76. The pulsations in HL Tau 76 cover a wide range of periods between 380 s and 1390 s. We propose an identification for 39 of those 43 frequencies in terms of = 1 and = 2 non-radial g-modes split by rotation. We derive an average rotation period of 2.2 days. The period distribution of HL Tau 76 is best reproduced if the star has a moderately "thick" hydrogen mass fraction log q H ≥ −7.0. The results presented in this paper constitute a starting point for a detailed comparison of the observed periods with the periods calculated for models as representative as possible of HL Tau 76.

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Section: Introductionmentioning

confidence: 99%

Whole Earth telescope observations of the ZZ Ceti star HL Tau 76

Dolez

Vauclair²,

Kleinman³

et al. 2006

A&A

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“…We detect periods in J0840 ranging from roughly 180 to 800 s meanwhile pulsational periods of BPM 37093 lie in a narrow range of about 510 to 660 s (Kanaan et al 2005) and those of GD 518 range from 425 to 595 s (Hermes et al 2013). Our observed period range is consistent with the calculated period range for a 1.1 M CO-core WD with T eff = 12, 200 K presented in Figure 9 of Montgomery & Winget (1999), which shows the periods of l=2 modes for crystallized mass ratios ranging from 0 to 0.99.…”

Section: Discussionmentioning

confidence: 81%

“…Previous studies of BPM 37093, the most extensively observed high mass DAV, have encountered difficulty with mode identification since its modes are both low amplitude and undergo amplitude modulation (Kanaan et al 2005). Furthermore, amplitudes reported for GD 518 range from roughly 1 to 4 mma (Hermes et al 2013).…”

Section: Discussionmentioning

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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“…A major glitch occurs when the interior nuclei settle into a crystal and lock up in zero point fluctuations much of the energy that could otherwise be radiated (Mestel & Ruderman 1967). For only one star is the crystallization expected within the ZZ Ceti strip, and its period spacing suggests that half or thereabouts of the interior has indeed crystallized (Kanaan et al 2005;Brassard & Fontaine 2005).…”

Section: White Dwarfsmentioning

confidence: 99%

Astrophysics in 2005

Trimble

Aschwanden

Hansen

2006

PUBL ASTRON SOC PAC

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ABSTRACT. We bring you, as usual, the Sun and Moon and stars, plus some galaxies and a new section on astrobiology. Some highlights are short (the newly identified class of gamma-ray bursts, and the Deep Impact on Comet 9P/Tempel 1), some long (the age of the universe, which will be found to have the Earth at its center), and a few metonymic, for instance the term "down-sizing" to describe the evolution of star formation rates with redshift.

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Whole Earth Telescope observations of BPM 37093: A seismological test of crystallization theory in white dwarfs

Cited by 64 publications

References 28 publications

Whole Earth telescope observations of the ZZ Ceti star HL Tau 76

Whole Earth telescope observations of the ZZ Ceti star HL Tau 76

Four new massive pulsating white dwarfs including an ultramassive DAV

Astrophysics in 2005

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