Scientists have discovered a pair of stars locked in an incredibly close orbit that circle each other once every 51 minutes – and according to the results of a new study, they are only going to speed up.
The universe is a chaotic place when it comes to orbital mechanics. Our solar system, when viewed in relation to the rest of the cosmos, is a little vanilla. We have our central star – the Sun – which is orbited by eight major planets that are in turn are escorted through the heavens by a plethora of moons and rings of varying levels of impressiveness.
However, astronomers have discovered that roughly half of the stellar systems in our Milky Way are actually comprised of multiple stars that are gravitationally bound to one another. The Alpha Centauri system – which is the closest neighboring stellar population to our Sun – is in fact a collection of three stars that orbit one another roughly 4 light-years from Earth.
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Stars are among the most massive and dynamic bodies in the universe, and so, naturally, binary star systems can have some pretty extreme characteristics.
In a new study, a team of scientists have discovered a rare pair of stars known as a ‘cataclysmic variable’, which complete a full orbit of one another in less than an hour.
A cataclysmic variable is a system in which a super dense white dwarf star orbits another stellar body similar to our Sun. White dwarfs are the planet-sized cores of stars that have expended their nuclear fuel and thrown off their outer layers.
In a cataclysmic variable system, a super-dense white dwarf orbits a companion star so closely that its gravity allows it to actually steal hydrogen away from the larger stellar body’s atmosphere.
The newly discovered star system, which has been imaginatively named ZTF J1813+4251, was first discovered by researchers pouring over the Zwicky Transient Facility (ZTF) survey. The catalog contains high-resolution images of over a billion stars, and tracks variations in their apparent brightness over time.
Kevin Burdge, one of the authors of the new study published in the scientific journal Nature, used a computer algorithm to sort through the ZTF catalog in order to find flashes in the light signature of distant bodies that would suggest the presence of two closely orbiting stars.
This search flagged up around 1 million stars out of the billion-strong database. ZTF J1813+4251 stood out among the candidates, with the flashes of light from the distant source suggesting that it was a binary system.
Follow-up observations by the powerful Gran Telescopio Canarias in Spain and the W.M. Keck Observatory in Hawaii, discerned the radii, masses, and orbits of the two oddball stars.
It was revealed that ZTF J1813+4251 was likely a cataclysmic variable, made up of a geriatric star roughly the size of Jupiter with a mass the equivalent to 1/10th that of our Sun. This stellar body orbits with an ultra-dense white dwarf, which boasted a mass roughly half as great as our Sun, packed into a space 1/100th its volume, according to a press release from the Massachusetts Institute of Technology.
Incredibly, these two stellar bodies appear to circle one another once every 51 minutes – giving them the shortest orbit of any cataclysmic variable discovered to date.
The researchers took the data on ZTF J1813+4251 and used it to simulate the duo’s likely evolutionary path stretching over one hundred million years into the future. The results suggest that the stars are currently in a transitional phase, wherein the white dwarf is stripping away vast quantities of hydrogen from the atmosphere of the larger star.
This process will likely continue until all that remains is a helium dominated core. Over the next 70 million years this dense core will draw the pair into an even tighter orbital period of just 18 minutes.The results support an earlier study that predicted this behaviour from cataclysmic variables.
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Anthony Wood is a freelance science writer for IGN
Image Credit: Credit: M.Weiss/Center for Astrophysics | Harvard & Smithsonian