Scientists have discovered a binary star system called ZTF J1813+4251 located about 3,000 light-years away from us, and the orbital period of the included lights is just 51 minutes. This means that each of them takes a record short time to go around the other object.
One of them is a Sun-like star nearly the size of Jupiter, and its companion is a white dwarf—the dense core left over from the star. Under the influence of its gravity, it absorbs hydrogen from its partner’s atmosphere and slowly destroys it.
Such binary systems are abundant in the Milky Way galaxy. A few of them have an orbital period of less than 1 hour, although 51 minutes has never been observed before.
ZTF J1813+4251 is in a rare category of cataclysmic variable stars that combines a Sun-like luminosity and a white dwarf that have been approaching each other for billions of years. When the latter absorbs matter from its partner, powerful streams of light are produced, reminiscent of the explosion of a star.
There was an assumption that the merged objects in such systems move very quickly, which happens when the white dwarf begins to absorb helium instead of hydrogen. Scientists say that ZTF J1813+4251 is in just such a transition stage.
According to simulations, in about 70 million years, the orbital period of these stars will decrease to 18 minutes, after which the Sun-like luminosity, instead of contracting, will already expand and move away from the white dwarf.
The authors’ work was published in Nature.