Incredible ‘teardrop star’ discovery breaks the mould for astronomers

Amateur astronomers may have just found the oddest couple in the universe — and no, they’re not living on Earth.

Scientists say they’ve identified an extremely rare star that’s been warped into a never-before-seen teardrop shape by the gravity of its neighbour, a much smaller red dwarf.

They’re two halves of binary star system some 15,000 light years away, according to the findings published in the Nature Astronomy journal.

“I’ve been looking for a star like this for nearly 40 years,” said study co-author Don Kurtz, a visiting professor at the University of Sydney. “Now, we have finally found one.”

The teardrop star is about 1.7 times the mass of our own sun, and it desperately needs a better name than its current designation, HD74423. It gets its teardrop shape from the nearby red dwarf star — i.e. the old “ball and chain” — which has a gravitational pull strong enough to warp HD74423’s surface toward it.

The teardrop star is also unusual in that its a “one-sided pulsator” — something astronomers have never seen before. Other stars pulse at their own rhythmic rates.

Amateur astronomers first spotted the unusual star while perusing data from NASA’s Transiting Expoplanet Survey Satellite (TESS), which is dedicated to hunting planets. They noticed distortions in the larger star’s gravity, which prompted them to flag it to others who were also monitoring the phenomenon.

“As the binary stars orbit each other we see different parts of the pulsating star,” study co-author David Jones said in a news release from the University of Sydney.

“Sometimes we see the side that points towards the companion star, and sometimes we see the outer face.”

The new study was assembled by an international team of scientists who have been trying for years to figure out what’s going on with this particular star.

“What first caught my attention was the fact it was a chemically peculiar star,” said Simon Murphy, another researcher at the University of Sydney’s Sydney Institute for Astronomy.

“Stars like this are usually fairly rich with metals,” Murphy said. “But this metal is poor, making it a rare type of hot star.”

Astronomers believed that such a star might exist, but have never been able to spot one until now.

They hope the new discovery will lead to more one-sided pulsator findings in the future.


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