  We present an eccentric precessing gas disk model designed to study the
variable circumstellar absorption features detected for WD 1145+017, a metal
polluted white dwarf with an actively disintegrating asteroid around it. This
model, inspired by one recently proposed by Cauley et al., calculates
explicitly the gas opacity for any predetermined physical conditions in the
disk, predicting the strength and shape of all absorption features, from the UV
to the optical, at any given phase of the precession cycle. The successes and
failures of this simple model provide valuable insight on the physical
characteristics of the gas surrounding the star, notably its composition,
temperature and density. This eccentric disk model also highlights the need for
supplementary components, most likely circular rings, in order to explain the
presence of zero velocity absorption as well as highly ionized Si IV lines. We
find that a precession period of $4.6\pm0.3$ yrs can successfully reproduce the
shape of the velocity profile observed at most epochs from April 2015 to
January 2018, although minor discrepancies at certain times indicate that the
assumed geometric configuration may not be optimal yet. Finally, we show that
our model can quantitatively explain the change in morphology of the
circumstellar features during transiting events.
