GSN 069 -- A Tidal Disruption Near-Miss
  I suggest that the quasiperiodic ultrasoft X-ray eruptions recently observed
from the galaxy GSN 069 may result from accretion from a low-mass white dwarf
in a highly eccentric orbit about its central black hole. At 0.21M_sun, this
star was probably the core of a captured red giant. Such events should occur in
significant numbers as less extreme outcomes of whatever process leads to tidal
disruption events. I show that gravitational radiation losses can drive the
observed mass transfer rate, and that the precession of the white dwarf orbit
may be detectable in X-rays as a superorbital quasiperiod P_super ~ 2 d. The
very short lifetime of the current event, and the likelihood that similar ones
involving more massive stars would be less observable, together suggest that
stars may transfer mass to the low-mass SMBH in this and similar galaxies at a
total rate potentially making a significant contribution to their masses. A
similar or even much greater inflow rate would be unobservable in most
galaxies. I discuss the implications for SMBH mass growth.
