The rare discovery is the second fastest pair ever to be discovered and crashes at each other at speeds of up to hundreds of kilometers per second. The two white dwarf stars end one orbit around each other every seven minutes. It is also known as an eclipse binary system because one of the stars repeatedly crosses the other. These two are very dense, similar in size to the Earth. Combined, they contain a mass similar to that of our sun.
The two stars are so close that they can both enter Saturn. The distance between them is 47,780 miles, or one fifth of the distance between the Earth and the Moon. Their close orbit is due to the fact that stars have started as a couple. They have gone through various stages together, from ballooning to red giants to dead white dwarfs. Their particular behavior allowed astronomers to determine their size, mass, and short orbital period. Details were published in Nature magazine.