Astronomers detected four white dwarfs hidden in binary systems with red dwarf companions, all within 65 light-years of Earth. The team, led by Mairi O'Brien of the University of Warwick, used radial velocity measurements to spot telltale wobbles in the red dwarfs' motion, then confirmed the white dwarfs using ultraviolet observations from the Hubble Space Telescope. One of the systems, G 203-47 at 25 light-years away, ranks among the ten closest white dwarfs to our solar system. This marks the first detection of white dwarfs in nearby binary systems.
The discovery validates theoretical predictions, which estimated four to five such pairs should exist within 65 light-years. G 203-47 shows unusual characteristics: its red dwarf companion rotates once every 100 days but orbits the white dwarf in 15 days, suggesting the pair underwent different evolutionary processes than similar systems. Only about 30 percent of red dwarfs within 20 parsecs have been systematically surveyed for white dwarf companions, and researchers estimate nine to ten additional hidden pairs may remain undiscovered in the local stellar neighborhood. The team published their findings in Monthly Notices of the Royal Astronomical Society on July 14.