Research

'Dead planets around dead stars'

Polluted White Dwarfs

Once a star, similar to our Sun, ceases fusing hydrogen, it will undergo a violent stage of stellar evolution resulting in the production of a small, hot and dense stellar core. This is a white dwarf. It has been demonstrated that although the inner planetary system is engulfed during the red giant stage, the outer planetary system can survive. Evidence for the survival of outer planetary systems to the white dwarf phase comes from observations of planetary material polluting the atmospheres of white dwarfs. At least 30% of white dwarfs have been observed with elements heavier than helium in their atmospheres. The rapid gravitational settling times in comparison to the white dwarf's cooling age implies ongoing accretion from an external reservoir. So we are witnessing exo-planetary destruction in action. These white dwarf systems with atmospheric pollutants are called polluted white dwarfs.


My Research

My research foci in the area of polluted white dwarfs are:

  • To search for and constrain variability in the dust that surrounds polluted white dwarfs. I use near and mid infrared observations of the dust to do this. It is thought that the source of the pollution is tidally disrupted extrasolar planetesimals which have been scattered towards the white dwarf, so I aim to understand this process.
  • To search for variability in the metal spectral features in the white dwarf atmospheres. The aim is to understand if the accretion onto white dwarfs is constant. This can give us insight into how the material ends up in the atmosphere of the white dwarf.
  • To find and understand the composition of the planetary material that is accreting onto the white dwarfs. This is a unique way to discover the bulk composition of exo-planetary material.


Publications

  • Host-star and exoplanet compositions: a pilot study using a wide binary with a polluted white dwarf , Bonsor, A., Jofré, P., Shorttle, O., Rogers, L.K., et al., 2020., MNRAS Link to publication
  • Serendipitous discovery of a dusty disc around WDJ181417.84-735459.83 , González Egea, E., Raddi, R., Koester D., Rogers, L.K., et al., 2020., MNRAS, 501(3), p.3916. Link to publication
  • Near-infrared observations of dusty white dwarfs, Rogers, L.K. , Xu, S., Bonsor, A., Hodgkin, S., Su, K.Y., von Hippel, T. and Jura, M., 2020, IAU. Proceedings of the International Astronomical Union, 15(S357), 33-36. Link to publication
  • Exocomets from a Solar System Perspective , Strøm, P. A., Bodewits, D., ... Rogers, L.K., et al., 2020, PASP, 132(1016), 101001. Link to publication
  • Near-infrared variability in dusty white dwarfs: tracing the accretion of planetary material, Rogers, L.K. , Xu, S., Bonsor, A., Hodgkin, S., Su, K.Y., von Hippel, T. and Jura, M., 2020, MNRAS, 494(2), p.2861. Link to publication
  • Infrared Variability of Two Dusty White Dwarfs , Xu, S., Su, K.Y., Rogers, L.K., et al., 2018, ApJ, 866(2), p.108. Link to publication
  • Dust Production and Depletion in Evolved Planetary Systems, Farihi, J., van Lieshout, R., ... Rogers, L.K., et al., 2018, MNRAS, 481(2), pp.2601-2611. Link to publication