Advisor: Jared Males, University of Arizona

White dwarfs (WD) are currently the only probes of the interior composition of planets. Their extreme gravity causes elements to stratify, with the heaviest elements drawn to the center, with only hydrogen or helium remaining on the surface. Elements sink quickly, so any metals observed in a WD's spectrum must have been deposited recently from the planetary region around the star. This "pollution" has been shown to come from disintegrated planets, planetesimals, and dust disks around the WD. Polluted WD spectra has been used to probe the refractory (non-volatile) compositions of exoplanets and a lot of other really cool exoplanet science.

Broadly I am interested in how wide stellar companions affect the planetary systems of stars. White dwarfs in binaries with Main Sequence stars provide probes of planetary systems at the end of life of a star in the binary. Understanding the role of the wide companion in formation and long-term evolution of panetary systems, as well as its role in driving material on the WD surface, is hampered by low population statistics. Most known WDs in MS binaries are companions to M-dwarf stars, where the WD is easily detectable as its blue color dominates the spectrum of the system. Must fewer known are the so-called "Sirius-Like Systems", where the WD companion is drowned out by the light of the brighter A, F, G, or K type companion (Sirius, an early A star, has a white dwarf companion Sirius B, the first known WDMS system). This sounds like a job for high-contrast imaging!

The ExAO Pup Search has three main goals:

  • Detect new wide WDMS systems with MagAO-X and SCExAO and observe new systems for pollution with VIS-X and HST. (wide = separated enough to be resolved)
  • Montior orbits of new and previously known resolved WDMS systems to determine prevalence of high-eccentricity orbits of MS companions for polluted WDs and compare to estimated orbital parameters for the binary to be influencing pollution
  • Determine pollution rates for WDMS systems compared the single WDs as a function of cooling age
    • (The name is a reference to Sirius A - the dog star - and Sirius B - the pup!)

    This project is just getting started and will be a long-term investigation. I started collecting data in fall 2022. Below is the detection of a brand new never-before-seen white dwarf companion to a main sequence star (behind the mask)!