Variability of Hypervelocity Stars
  We present time-series photometry of 11 hypervelocity stars (HVSs) to
constrain their nature. Known HVSs are mostly late-B spectral type objects that
may be either main-sequence (MS) or evolved blue horizontal branch (BHB) stars.
Fortunately, MS stars at these effective temperatures, $T_{eff} \sim$ 12,000 K,
are good candidates for being a class of variable stars known as slowly
pulsating B stars (SPBs). We obtained photometry on four nights at the WIYN 3.5
m telescope, and on six nights on the 2.4 m Hiltner telescope. Using sinusoidal
fits, we constrain four of our targets to have periods between $P \sim 0.2 - 2$
days, with a mean value of 0.6 days. Our amplitudes vary between $A = 0.5 -
3$%. This suggests that these four HVSs are SPBs. We discuss a possible origin
for these stars, and why further observations are necessary.
