PREDNASAJUCI / LECTURER :

Andrii Maliuk

NAZOV / TITLE :

Alternative model of shallow ultraviolet transits of WD 1145+017

ABSTRAKT / ABSTRACT :
WD 1145+017 (WD1145) 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 
ultraviolet (UV) transits. In the UV diapason, transits of WD 1145 are always shallower than in the 
optical region. We developed our own model explaining these phenomena. Our explanation is based on 
optical properties of dust from disintegrating bodies: forward scattering is much stronger in UV 
compared to the optical region, leaving more UV photons in the original direction during the transit. 
Grains of silicate and iron of 1-10 microns in size fit observed transit depth ratios the best. 
This can explain the two shallow UV transits of Xu et al. (2019). Two other might require more optically 
thick dust and more sophisticated 3D radiative transfer modeling.