A star disrupted by a stellar black hole as the origin of the cloud
  falling toward the Galactic center
  We propose that the cloud moving on a highly eccentric orbit near the central
black hole in our Galaxy, reported by Gillessen et al., is formed by a
photoevaporation wind originating in a disk around a star that is tidally
perturbed and shocked at every peribothron passage. The disk is proposed to
have formed when a stellar black hole flew by the star, tidally disrupted its
envelope, and placed the star on its present orbit with some of the tidal
debris forming a disk. A disrupting encounter at the location of the observed
cloud is most likely to be caused by a stellar black hole because of the
expected dynamical mass segregation; the rate of these disk-forming encounters
may be as high as $\sim 10^{-6}$ per year. The star should also be spun up by
the encounter, so the disk may subsequently expand by absorbing angular
momentum from the star. Once the disk expands up to the tidal truncation
radius, the tidal perturbation of the outer disk edge at every peribothron may
place gas streams on larger orbits which can give rise to a photoevaporation
wind that forms the cloud at every orbit. This model predicts that, after the
cloud is disrupted at the next peribothron passage in 2013, a smaller
unresolved cloud will gradually grow around the star on the same present orbit.
An increased infrared luminosity from the disk may also be detectable when the
peribothron is reached. We also note that this model revives the encounter
theory for planet formation.
