  WD 1145+017 is the first white dwarf known to be orbited by disintegrating
exoasteroids. It is a DBZ-type white dwarf with strongly variable broad
circumstellar lines and variable shallow UV transits. Various models of the
dust clouds and gaseous rings have been proposed as an explanation for this
behavior. Here we propose alternative models.The simple radiative transfer code
Shellspec was modified for this purpose and used for testing the new dust cloud
and gas disk models. We used modified TLUSTY and SYNSPEC codes to calculate
atmosphere models assuming the LTE or NLTE, and to calculate the intrinsic
spectrum of the star. We then used these atmosphere models to estimate the mass
of the radiative and convective zones and NLTE spectrum synthesis to estimate
their chemical composition. We offer an alternative explanation of some (not
all) shallow UV transits. These may be naturally caused by the optical
properties of the dust grains: opacities and mainly phase functions as a result
of the forward scattering. The latter is much stronger in UV compared to the
optical region, leaving more UV photons in the original direction during the
transit. We also developed an alternative model of the gaseous disk, consisting
of an inner, hotter, and almost circular disk and an outer, cooler, and
eccentric disk. The structure precesses with a period of $3.83 \pm 0.12$ yr. We
demonstrate that it fits the observed circumstellar lines reasonably well.
These alternative models solve a few drawbacks that might be associated with
the previous models, but they also have their own disadvantages. We confirm
that the chemical composition of the atmosphere is similar to that of CI
chondrites but C, N, and S are significantly underabundant and much closer to
the bulk Earth composition. This is a strong argument that the star has
recently encountered and accreted material from a body of Earth-like
composition.
