Speaker
Description
ELMs are white dwarf stars with masses that are too low ($\lesssim$ 0.3 $M_\odot$) to be formed through single stellar evolution. Many of the observed ELMs have been found to be strong gravitational wave sources that will be detectable by LISA. Their higher brightness compared to canonical white dwarfs makes them valuable laboratories for the development of multi-messenger astronomy. Binary interaction seems to play an important role in the formation of ELMs since it can cause the mass-loss required to explain their masses. This raises important questions: Do all low-mass white dwarfs result from binary evolution, or can other evolutionary paths exist? Does the companion always survive the interaction, or can it be destroyed, leaving behind a single low-mass white dwarf?
My PhD research aims to get new insights about these questions, as will be shown in this talk. To achieve this, I have selected a complete volume-limited sample of ELM candidates from the Gaia DR2 ELM candidates catalogue.
By cross-matching this sample with archives of spectroscopic data (such as SOAR, ESO, INT, LAMOST), I have obtained spectra for 75% of the targets. To complete the sample, I plan to obtain follow-up spectroscopy for the remaining 25% of candidates.
The spectral analysis will allow me to characterize the candidates by fitting parameters such as effective temperature and surface gravity, as well as study ELMs binary fraction by estimating radial velocities.
