  Being the first of its kind, the white dwarf WD 1145+017 exhibits a complex
system of disintegrating debris which offers a unique opportunity to study its
disruption process in real time. Even with plenty of transit observations there
are no clear constraints on the masses or eccentricities of such debris. Using
$N$-body simulations we show that masses greater than approximately $10^{20}$
kg (a tenth of the mass of Ceres) or orbits that are not nearly circular
($\mathrm{eccentricity}>10^{-3}$) dramatically increase the chances of the
system becoming unstable within two years, which would contrast with the
observational data over this timespan. We also provide a direct comparison
between transit phase shifts detected in the observations and by our numerical
simulations.
