  With XMM-Newton and the Spitzer Space Telescope, we obtain upper bounds to
the X-ray fluxes from G29-38 and GD 362, and the 70 micron flux from G29-38.
These data provide indirect evidence that G29-38 is accreting from a
tidally-disrupted asteroid: it is neither accreting large amounts of hydrogen
and helium nor is its surrounding dusty disk being replenished from a reservoir
of cold grains experiencing Poynting-Robertson drag. The upper bound to the
X-ray flux from GD 362 is consistent with the estimated rate of mass accretion
required to explain its pollution by elements heavier than helium. GD 362 also
possesses 0.01 of an Earth's mass of hydrogen, an anomalously large amount for
a white dwarf with a helium-dominated atmosphere. One possibility is that
before the current disk was formed, this hydrogen was accreted from either
about 100 Ceres-like asteroids or one large object. An alternative scenario
which simultaneously explains all of GD 362's distinctive properties is that we
are witnessing the consequences of the tidal-destruction of a single parent
body that had internal water and was at least as massive as Callisto and
probably as massive as Mars.
