research Massive Algol binaries Eclipsing, double-lined spectroscopic binary systems caught during mass transfer- excellent systems to understand mass-transfer physics, tidal theory, and internal mixing processes. Wolf-Rayet binaries In very massive binaries, mass transfer can occur from a more massive star to a less massive star on a nuclear timescale, and form Wolf-Rayet stars can be on the main sequence. Black hole X-ray binaries Determining observable signatures of immediate progenitors of binary black hole binaries
