Astronomers have confirmed four white dwarf stars previously hidden in binary systems within 65 light-years of Earth. One system, located just 25 light-years away, ranks as the ninth closest known white dwarf to the Sun.
Researchers at the University of Warwick and the University of Colorado Boulder made the detections using ultraviolet data from the Hubble Space Telescope. Each white dwarf orbits a brighter red dwarf companion that had masked its presence in visible light observations.
The findings match earlier predictions that four to five such close binary systems should exist within 20 parsecs. One system, G 203-47, required 27 years of follow-up after its radial velocity wobble was first noted.
Dr. Mairi O’Brien of the University of Warwick noted that the companions were undetectable at visible wavelengths until targeted ultraviolet observations were applied. Coauthor Dr. David Wilson highlighted that the slow rotation of the red dwarf in G 203-47 suggests varied evolutionary paths among these binaries.
Professor Pier-Emmanuel Tremblay added that only about 30 percent of nearby red dwarfs have been surveyed this way, leaving open the possibility of additional undetected systems.