Two incredibly fast-orbiting stars seem to be the wrong temperature

[Judi Lynn]

SPACE 24 July 2019

By Leah Crane

Round and round the two stars go. Whether they’ll stop, nobody knows. Two white dwarf stars are twirling around one another at an extraordinarily fast rate, and we don’t know whether they will eventually smash together or just keep orbiting.

Kevin Burdge at the California Institute of Technology and his colleagues sifted through about 20 million datasets from the Zwicky Transient Facility, a sky survey that watches for objects which rapid changes in their brightness, to look for signals from pairs of white dwarf stars. They found one binary, called ZTF J153932.16 + 502738.8, that was particularly interesting.

Further observations revealed that there was a deep dip in the light from the system every 6.91 minutes. In a binary star system, this type of dip is caused when the cooler star passes between the hotter one and our telescopes, blocking out its light in an eclipse. This means that the two stars take less than 7 minutes to circle around one another.

“There have been other ultra-short orbital period binaries found before, but the signal was so low that we were never really sure that they were what we thought,” says Burdge. “This one is eclipsing, so it’s the first unambiguous detection of a system under 10-minute period.”

Read more: https://www.newscientist.com/article/2211009-two-incredibly-fast-orbiting-stars-seem-to-be-the-wrong-temperature/#ixzz5ufO44FDa