Polluted white dwarfs and planetary debris with the CUBES spectrograph

The exoplanets research in the last decade focused on planets’ detection and atmosphere’s characterization through spectroscopy, but there is a lack of data regarding the core composition. Planets’ evolution is strongly influenced by their central star, and research on evolved planetary systems is a main focus. The last stage of stellar evolution for medium-mass stars is usually a white dwarf and nearly 97% of our galaxy stars will end up as white dwarfs. In most cases, stellar winds during stellar evolution will eventually completely disrupt the planetary system, with a formation of a protoplanetary disk, and material from the disk would fall back on the white dwarf surface. The effect is called photospheric pollution, characterised by absorption lines of heavy elements, as iron and silicate. It has been observed that the process could bring on the star any debris within the accretion radius, including planetesimals. The scope of this project is investigating the possibility for a new incoming instrument, CUBES (ESO), to observe such absorption lines and the prospective of research. CUBES is a spectrograph with Cassegrain focus covering at high efficiency the UV ground-based region (300 – 400 nm) with intermediate resolution. Its scientific goals encompass both Galactic and extra-Galactic astronomy, in particular detecting iron and heavy elements. In this work, by simulating spectra at high resolution of polluted white dwarfs and analyzing them in the range 300-400 nm, I tested the possibility of using CUBES in the context of future rocky planets research through white dwarfs exogeology. Detecting elements and calculating their abundances, it is possible as explained above to model the process of accretion on the star, and retrieve the planetesimals characteristics, such as the geological composition.