This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Current gravitational-wave observatories aren't sensitive enough to capture the gravitational waves of binary stars. They can only see the gravitational chirps of black holes just as they are merging.
But that will change as more sensitive instruments are developed. Recently, a team of astronomers discovered a binary white dwarf system that could be a good target for advanced gravitational-wave observatories. The work is published in The Astrophysical Journal Letters.
The system is known as eRASSU J0608. It's an X-ray source that has a bright pulse every 374 seconds, or just over six minutes. Usually, when a repeating source such as this is observed, it is due to some kind of periodic motion.
Pulsars are due to the rotation of a neutron star. Many variable stars are eclipsing binaries. So the team wanted to see what was behind eRASSU J0608.
Using data from the Neutron Star Interior Composition Explorer (NICER) and the Einstein Probe X-ray observatory, they were able to see that the system is a close-orbiting pair of white dwarf stars. They orbit so closely that material ejected from one of the stars is directly captured by the other instead of forming an accretion disk around the two stars. This is why the X-rays are emitted in regular bursts rather than having a constant glow.
The X-rays of the superheated material can be seen when things line up just so. The authors then compared their new data with older observations from XMM-Newton. From this, they could look at how the system changed over a span of more than three years.
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