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Title: 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

Abstract

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 0.51–0.73 M {sub ⊙}more » white dwarfs, which evolved from 1.7–3.0 M {sub ⊙} 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.« less

Authors:
; ; ; ; ;  [1]; ; ; ; ; ; ;  [2];  [3]; ; ;  [4];  [5]
  1. Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599 (United States)
  2. Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)
  3. Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States)
  4. Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States)
  5. Wesleyan University Astronomy Department, Van Vleck Observatory, 96 Foss Hill Drive, Middletown, CT 06459 (United States)
Publication Date:
OSTI Identifier:
22661086
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal, Supplement Series; Journal Volume: 232; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANGULAR MOMENTUM; HARMONIC OSCILLATORS; HARMONICS; HYDROGEN; LINE WIDTHS; MASS; OSCILLATION MODES; OSCILLATORS; PHOTOMETRY; PULSATIONS; ROTATION; SPACE; SPECTROSCOPY; TELESCOPES; WHITE DWARF STARS

Citation Formats

Hermes, J. J., Fanale, S. M., Dennihy, E., Fuchs, J. T., Dunlap, B. H., Clemens, J. C., Gänsicke, B. T., Greiss, S., Tremblay, P.-E., Fusillo, N. P. Gentile, Raddi, R., Chote, P., Marsh, T. R., Kawaler, Steven D., Bell, Keaton J., Montgomery, M. H., Winget, D. E., and Redfield, S., E-mail: jjhermes@unc.edu. 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. United States: N. p., 2017. Web. doi:10.3847/1538-4365/AA8BB5.
Hermes, J. J., Fanale, S. M., Dennihy, E., Fuchs, J. T., Dunlap, B. H., Clemens, J. C., Gänsicke, B. T., Greiss, S., Tremblay, P.-E., Fusillo, N. P. Gentile, Raddi, R., Chote, P., Marsh, T. R., Kawaler, Steven D., Bell, Keaton J., Montgomery, M. H., Winget, D. E., & Redfield, S., E-mail: jjhermes@unc.edu. 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. United States. doi:10.3847/1538-4365/AA8BB5.
Hermes, J. J., Fanale, S. M., Dennihy, E., Fuchs, J. T., Dunlap, B. H., Clemens, J. C., Gänsicke, B. T., Greiss, S., Tremblay, P.-E., Fusillo, N. P. Gentile, Raddi, R., Chote, P., Marsh, T. R., Kawaler, Steven D., Bell, Keaton J., Montgomery, M. H., Winget, D. E., and Redfield, S., E-mail: jjhermes@unc.edu. Sun . "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". United States. doi:10.3847/1538-4365/AA8BB5.
@article{osti_22661086,
title = {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},
author = {Hermes, J. J. and Fanale, S. M. and Dennihy, E. and Fuchs, J. T. and Dunlap, B. H. and Clemens, J. C. and Gänsicke, B. T. and Greiss, S. and Tremblay, P.-E. and Fusillo, N. P. Gentile and Raddi, R. and Chote, P. and Marsh, T. R. and Kawaler, Steven D. and Bell, Keaton J. and Montgomery, M. H. and Winget, D. E. and Redfield, S., E-mail: jjhermes@unc.edu},
abstractNote = {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 0.51–0.73 M {sub ⊙} white dwarfs, which evolved from 1.7–3.0 M {sub ⊙} 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.},
doi = {10.3847/1538-4365/AA8BB5},
journal = {Astrophysical Journal, Supplement Series},
number = 2,
volume = 232,
place = {United States},
year = {Sun Oct 01 00:00:00 EDT 2017},
month = {Sun Oct 01 00:00:00 EDT 2017}
}