White Dwarf Rotation as a Function of Mass and a Dichotomy of Mode Line Widths: Kepler. Observations of 27 Pulsating DA White Dwarfs through K2 Campaign 8

被引：137

作者：

Hermes, J. J. ^{[1
]}

Gansicke, B. T. ^{[2
]}

Kawaler, Steven D. ^{[3
]}

Greiss, S. ^{[2
]}

Tremblay, P. -E. ^{[2
]}

Fusillo, N. P. Gentile ^{[2
]}

Raddi, R. ^{[2
]}

Fanale, S. M. ^{[1
]}

Bell, Keaton J. ^{[4
]}

Dennihy, E. ^{[1
]}

Fuchs, J. T. ^{[1
]}

Dunlap, B. H. ^{[1
]}

Clemens, J. C. ^{[1
]}

Montgomery, M. H. ^{[4
]}

Winget, D. E. ^{[4
]}

Chote, P. ^{[2
]}

Marsh, T. R. ^{[2
]}

Redfield, S. ^{[5
]}

机构：

[1] Univ N Carolina, Dept Phys & Astron, Chapel Hill, NC 27599 USA

[2] Univ Warwick, Dept Phys, Coventry CV4 7AL, W Midlands, England

[3] Iowa State Univ, Dept Phys & Astron, Ames, IA 50011 USA

[4] Univ Texas Austin, Dept Astron, Austin, TX 78712 USA

[5] Wesleyan Univ, Astron Dept, Van Vleck Observ, 96 Foss Hill Dr, Middletown, CT 06459 USA

来源：

ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES | 2017年 / 232卷 / 02期

基金：

欧洲研究理事会; 美国国家科学基金会;

关键词：

stars: oscillations; stars: variables: general; white dwarfs; ZZ-CETI STARS; WHOLE EARTH TELESCOPE; SUPER-NYQUIST ASTEROSEISMOLOGY; GRAVITY MODES; SEISMOLOGICAL ANALYSIS; PHOTOMETRIC SELECTION; LUMINOSITY FUNCTIONS; INSTABILITY STRIP; COMPACT PULSATORS; ERROR-CORRECTION;

D O I：

10.3847/1538-4365/aa8bb5

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present photometry and spectroscopy for 27 pulsating hydrogen-atmosphere white dwarfs ( DAVs; a. k. a. ZZ Ceti stars) observed by the Kepler space telescope up to K2 Campaign 8, an extensive compilation of observations with unprecedented duration (> 75 days) and duty cycle (> 90%). The space-based photometry reveals pulsation properties previously inaccessible to ground-based observations. We observe a sharp dichotomy in oscillation mode line widths at roughly 800 s, such that white dwarf pulsations with periods exceeding 800 s have substantially broader mode line widths, more reminiscent of a damped harmonic oscillator than a heat-driven pulsator. Extended Kepler coverage also permits extensive mode identification: we identify the spherical degree of 87 out of 201 unique radial orders, providing direct constraints of the rotation period for 20 of these 27 DAVs, more than doubling the number of white dwarfs with rotation periods determined via asteroseismology. We also obtain spectroscopy from 4 m-class telescopes for all DAVs with Kepler photometry. Using these homogeneously analyzed spectra, we estimate the overall mass of all 27 DAVs, which allows us to measure white dwarf rotation as a function of mass, constraining the endpoints of angular momentum in low-and intermediate-mass stars. We find that 0.51-0.73M(circle dot) white dwarfs, which evolved from 1.7-3.0M(circle dot) ZAMS progenitors, have a mean rotation period of 35 hr with a standard deviation of 28 hr, with notable exceptions for higher-mass white dwarfs. Finally, we announce an online repository for our Kepler data and follow-up spectroscopy, which we collect at http:// k2wd. org.

引用

页数：28