Two New Tidally Distorted White Dwarfs
  We identify two new tidally distorted white dwarfs (WDs), SDSS
J174140.49+652638.7 and J211921.96-001825.8 (hereafter J1741 and J2119). Both
stars are extremely low mass (ELM, < 0.2 Msun) WDs in short-period, detached
binary systems. High-speed photometric observations obtained at the McDonald
Observatory reveal ellipsoidal variations and Doppler beaming in both systems;
J1741, with a minimum companion mass of 1.1 Msun, has one of the strongest
Doppler beaming signals ever observed in a binary system (0.59 \pm 0.06%
amplitude). We use the observed ellipsoidal variations to constrain the radius
of each WD. For J1741, the star's radius must exceed 0.074 Rsun. For J2119, the
radius exceeds 0.10 Rsun. These indirect radius measurements are comparable to
the radius measurements for the bloated WD companions to A-stars found by the
Kepler spacecraft, and they constitute some of the largest radii inferred for
any WD. Surprisingly, J1741 also appears to show a 0.23 \pm 0.06% reflection
effect, and we discuss possible sources for this excess heating. Both J1741 and
J2119 are strong gravitational wave sources, and the time-of-minimum of the
ellipsoidal variations can be used to detect the orbital period decay. This may
be possible on a timescale of a decade or less.
