Astronomers have discovered a potential new planet locked in a death spiral

They next want to compare the results with the few other hot Jupiter-style planets out there to more accurately predict how planetary tides affect stars and vice-versa. “It likely formed farther away from the star and has migrated into a point where it’s being destroyed”, says lead author Christopher Johns-Krull, an astronomer at Rice University.

This is only possible because the planet is so close to the star, at about 2.5 million kilometres away. They concluded that it actually causes disruptive tides on the star that change its orbital speed. The planet is some 1,100 light-years from Earth and far too near to the star it orbits, this make it hot and likely in danger. However, young PTFO8-8695 b and its early decaying condition indicated that it is something unique and special. We know there are close-orbiting planets around middle-aged stars that are presumably in stable orbits. It’s also incredibly rare: Before it was discovered in 2012, scientists didn’t think that gas giants could exist around stars as young as its host.

John-Krull released his findings, which will be published in the Astrophysical Journal later this year, on the academic paper sharing website arXiv this week. The team that compiled the evidence was co-led by Johns-Krull and Lowell Observatory astronomer Lisa Prato and included 10 co-authors from Rice, Lowell, the University of Texas at Austin, NASA, the California Institute of Technology and Spain’s National Institute of Aerospace.

Astronomers using the Hungarian-made Automated Telescope Network-South Exoplanet Survey spotted the big, gassy world around a star dubbed HATS-18, which is nearly identical in size and temperature to our sun. “We just sat on the star for a whole night”. So there was some skepticism that a planet had really been found.

PTFO 8-8695 b was first identified several years ago, when another team of researchers began noticing regular dips in the brightness of the star it orbits.

“The H alpha emission is very strong, nearly as strong as what’s coming from the star, even though the planet is only 3 percent of the size of the star”, John-Krull said.

“We don’t yet have absolute proof this is a planet because we don’t yet have a firm measure of the planet’s mass, but our observations go a long way toward verifying this really is a planet”, said Johns-Krull. “The gas has to be filling a much larger region where the gravity of the planet is no longer strong enough to hold on to it”.

The same thing happens in the Earth-moon system: Earth spins faster on its axis than the moon orbits around us, so the moon is moving away. “Does it eventually stop losing mass, or does it keep going until it falls into the star?”

List of planets observed in the universe has been increasing. But while young stars and their planets offer a valuable research subject for scientists, they’re not always easy to study – or even find.