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 \pm 0.3 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 .