I am a PhD student in the Astronomy and Astrophysics group at the University of Warwick. My supervisor is Pier-Emmanuel Tremblay.
Most stars end their lives by blowing off their outer layers and leaving a core remnant, known as a white dwarf, behind. White dwarfs are fascinating to study as they can be used to determine the ages of stars, calculate the initial-to-mass fraction and study remnant planetary systems. Additionally, due to their simple spectra, white dwarfs are good stars to use for calibration of telescopes. To be able to accomplish all this, we need to be able to determine the fundamental properties of white dwarfs, such as the mass, radius and temperature. Spectroscopy can be used to do this. By comparing a white dwarf spectrum with model spectra, we can determine its effective temperature and surface gravity, as well as the elemental abundances of its atmosphere.
Up to now, 1D models have been used to calculate model spectra of DB (helium-atmosphere) white dwarfs. However in 1D, the treatment of convection, which occurs in the atmospheres of white dwarfs, is unphysical. 3D models are thought to be more accurate as they treat convection using radiation-hydrodynamics. My work is to analyse the first 3D grid of DB white dwarf atmosphere models and quantify the differences between these new models and the standard 1D models.
These animations show radiative flux leaving the top of the simulations for two 3D DB models. On the left, a DB model with surface gravity of 107.5 cm s-² and effective temperature of around 10,000 K is shown. The DB model on the right, has surface gravity of 109 cm s-2 and effective temperature of around 34,000 K. Unlike the model with lower surface gravity and effective temperature, this model has well defined intergranular lanes. These models define the two extremes of the 3D DB grid I analyse.