Rare gravitational lens in binary system may reveal properties of exotic stars
Astronomers have discovered a unique pair of stars consisting of a white dwarf, the compact core of a dead star, and the sunlike star it orbits. When the white dwarf passes in front of its companion, as seen from Earth, the white dwarf’s gravity magnifies the other star’s light. The pair represents the first clear sign of a gravitational lens in a binary star.
The white dwarf — with a mass about 60 percent of the sun’s and a volume not much bigger than Earth’s — orbits a sun doppelgänger every 88 days, astronomers report in the April 18 Science. Ethan Kruse and Eric Agol of the University of Washington in Seattle discovered the binary, lurking 2,600 light-years away in the constellation Lyra, while mining data collected by the Kepler space telescope. Agol and another researcher