Two white dwarf stars have entered the record books with the fastest orbital period known for any stellar system. It takes just 5 min for these two Earth-sized stars to orbit each other – that’s 100,000 times faster than the Earth orbits the Sun. The stars exist in a rarely seen transitory state; with time, their orbit will slow considerably.
White dwarfs are normal stars that are slowly running out of energy as they reach the end of their lives – our Sun will eventually become one.
The pair was identified by the Chandra X-ray telescope as a variable X-ray source, with the emission cutting off every 5 min. At the time, it was not clear what was behind this variation.
Now, VLT observations have revealed a pair of white dwarfs and the spectral lines of ionized helium show a hot spot on the surface of one of the stars at a temperature of around 250,000 °C where X-rays are emitted. With such a short orbital period, the system is a prime candidate for gravitational wave observations.
Israel et al. To be published in Astronomy & Astrophysics Letters.
