The rare discovery is the second-fastest pair ever discovered that lashes at speeds of hundreds of miles per second. Every two minutes, the two white dwarf stars circle around each other. It is also known as a dimming binary system because one of the stars intersects repeatedly before the other.
A white dwarf star is the phase in the life cycle of a star when it loses its outer layers and depletes its nuclear fuel. These two are very dense, similar in size to the earth. Together, they contain a mass that resembles that of our sun.
The two stars circle so closely that they both fit into Saturn. The distance between them is 47,780 miles, or one fifth of the distance between Earth and the Moon.
Their tight orbit is due to the stars starting as a pair. They went through different phases together, from ballooning to red giants to dead white dwarfs.
"As the darker star passes in front of the brighter, it blocks most of the light, resulting in the seven-minute flashing pattern we see in the ZTF data," said study author Kevin Burdge, a Caltech graduate. "Matter is preparing to spill from the larger and lighter White Dwarf to the smaller and heavier that will eventually take down its lighter companion completely.We have seen many examples of a kind of system in which a white dwarf could largely exploit their companion, but we rarely catch these systems as they still grow together. "
The binary stars are also a well-known source of gravitational waves, also known as waves in space and time. The National Science Foundation's ground-based Laser Interferometer Gravitational Wave Observatory first discovered these waves in 2015, caused by the collision of two black holes.
Launched in 2034, the European Space Agency launched Laser Interferometer Space The antenna can detect these waves at lower frequencies.
"These two white dwarfs merge because they emit gravitational waves, and within a week of turning on LISA, the gravitational waves should be picked up by this system." Tom Prince, co-author of the study, Ira S. Bowen, a professor of physics at Caltech University and senior scientist at NASA's Jet Propulsion Laboratory. "LISA will find in our galaxy tens of thousands of binary systems like this, but so far we only know a few, and this binary star system is one of the best so far characterized by its darkness."
The pair is intriguing to astronomers for other reasons, including stellar evolution. It is known that other couples merge into one star or one cuts the other to pieces.
One of the stars is hotter than the other and reaches 50,000 degrees Celsius, nine times hotter than our Sun. The researchers believe that this star pulls material away from the other, causing it to heat up.
However, X-rays are typically generated in this process and none are observed in this system.
In the meantime, the duo will perform a show for the next hundred thousand years.