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Title: Radius constraints from high-speed photometry of 20 low-mass white dwarf binaries

We carry out high-speed photometry on 20 of the shortest-period, detached white dwarf binaries known and discover systems with eclipses, ellipsoidal variations (due to tidal deformations of the visible white dwarf), and Doppler beaming. All of the binaries contain low-mass white dwarfs with orbital periods of less than four hr. Our observations identify the first eight tidally distorted white dwarfs, four of which are reported for the first time here. We use these observations to place empirical constraints on the mass-radius relationship for extremely low-mass (≤0.30 M {sub ☉}) white dwarfs. We also detect Doppler beaming in several of these binaries, which confirms their high-amplitude radial-velocity variability. All of these systems are strong sources of gravitational radiation, and long-term monitoring of those that display ellipsoidal variations can be used to detect spin-up of the tidal bulge due to orbital decay.
Authors:
 [1] ;  [2] ; ;  [3] ; ;  [4] ; ; ; ; ; ;  [5] ;  [6]
  1. Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)
  2. Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)
  3. Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 West Brooks Street, Norman, OK 73019 (United States)
  4. School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington 6140 (New Zealand)
  5. Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States)
  6. Department of Physics, University of Texas at El Paso, El Paso, TX 79968 (United States)
Publication Date:
OSTI Identifier:
22365202
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 792; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMPLITUDES; BINARY STARS; DECAY; DEFORMATION; ECLIPSE; GALAXIES; GRAVITATIONAL RADIATION; LIMITING VALUES; MASS; PHOTOMETRY; RADIAL VELOCITY; SPIN; VARIATIONS; WHITE DWARF STARS