  We present thirteen epochs of near-infrared (0.8-5 micron) spectroscopic
observations of the pre-transitional, "gapped" disk system in SAO 206462 (=HD
135344B). In all, six gas emission lines (including Br gamma, Pa beta, and the
0.8446 micron line of O I) along with continuum measurements made near the
standard J, H, K, and L photometric bands were measured. A mass accretion rate
of approximately 2 x 10^-8 solar masses per year was derived from the Br gamma
and Pa beta lines. However, the fluxes of these lines varied by a factor of
over two during the course of a few months. The continuum also varied, but by
only ~30%, and even decreased at a time when the gas emission was increasing.
The H I line at 1.083 microns was also found to vary in a manner inconsistent
with that of either the hydrogen lines or the dust. Both the gas and dust
variabilities indicate significant changes in the region of the inner gas and
the inner dust belt that may be common to many young disk systems. If planets
are responsible for defining the inner edge of the gap, they could interact
with the material on time scales commensurate with what is observed for the
variations in the dust, while other disk instabilities (thermal,
magnetorotational) would operate there on longer time scales than we observe
for the inner dust belt. For SAO 206462, the orbital period would likely be 1-3
years. If the changes are being induced in the disk material closer to the star
than the gap, a variety of mechanisms (disk instabilities, interactions via
planets) might be responsible for the changes seen. The He I feature is most
likely due to a wind whose orientation changes with respect to the observer on
time scales of a day or less. To further constrain the origin of the gas and
dust emission will require multiple spectroscopic and interferometric
observations on both shorter and longer time scales that have been sampled so
far.
