Projects

White Dwarf Asteroseismology
Our group probes the interiors of stellar remnants using the tools of asteroseismology, by studying the periods of pulsating white dwarfs. A major improvement in our ability to determine these periods has been enabled by the Kepler and TESS space telescopes, and much of our work is coordinated through the TESS Asteroseismic Science Consortium (TASC).

White Dwarf Cosmochronology
One of the most unique aspects of white dwarfs is that since they no longer produce energy from fusion, their evolution is fundamentally a cooling problem. We are actively engaged in projects to assess the precision and accuracy of total ages of stars measured by using wide, coeval white dwarf companions.

Remnant Planetary Systems
Our group leads many searches to find and characterize the debris of remnant planetary systems around retired stars, using photometric surveys such as Kepler and TESS as well as other synoptic surveys like the Zwicky Transient Facility. We are also trying to constrain the occurrence rates of planetary systems around >3.5 solar-mass main-sequence stars.

Endpoints of Stellar Rotation
We explore the endpoints of angular momentum evolution in stars by measuring white dwarf rotation rates. We are also interested in finding evidence of past stellar merger events by observing and analyzing magnetic surface spots on white dwarfs.

White Dwarfs in Gaia
Our group is actively using data from the Gaia space mission to find and explore stellar remnants, especially extremely low-mass white dwarfs (<0.3 solar masses) and other byproducts of close binary evolution.

Supernova Survivors
Some Type Ia supernova events may not completely disrupt a white dwarf, and we are actively searching for new zombie stars that are supernova survivors. These stars have peculiar abundances, high space motions, and are oddly inflated.

Detailed information about these research areas and more can be found on the web site of the PI, JJ Hermes.