Distant sun-like star eating its planets, astronomers say
Discovery 'stroke of good luck,' researcher says
A new study suggests that a star 550 light-years away is gobbling up the remains of destroyed planets.
RZ Piscium is a sun-like star estimated to be between 30 and 50 million years old — an infant compared to our sun, which is about 4.5 billion years old.
Astronomers were puzzled by this peculiar star. It dimmed periodically, sometimes for up to two days, and at which time became as much as 10 times fainter.
In a new paper published in The Astronomical Journal, researchers suggest that a large, clumpy, dust cloud surrounds the star, blocking the light in the same manner a cloud hides the sun on a cloudy day. And, they say, the cloud likely comes from the remains at least one gaseous planet that was destroyed.
Stars and planets form large, rotating clouds of dust and gas. After a few million years, the gas disk usually disperses. In the case of RZ Piscium, however, the indication of dust suggested something else was at work.
Theories suggest that planets that form shortly after a star can migrate inwards. Tidal forces from the star essentially rip them apart, with the resulting gas from the young planet being consumed by the star. This, the researchers say, is the likely case for RZ Piscium.
'Complex' histories
The findings help astronomers better understand the evolution of stellar systems and their planets.
"It gives us this glimpse into this transition from the early formation of systems to the later stable systems; how this evolution occurs and that it really happens; that these planets really are migrating in; that they really do suffer extreme fates as they migrate into the star," Catherine Pilachowski, co-author of the paper, told CBC News.
"It's really fascinating to see how complex their early histories are," said Pilachowski, an astronomer at Indiana University.
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As stars form, they blow gas from the circumstellar disk outward with the rocky debris remaining closer, as seen in the NASA video below.
While scientists have a few theories on how our solar system formed, it's likely that the rocky debris that existed after the sun formed prevented the consumption of planets, though a recent study suggested our sun could have eaten an early planet.
While the researchers suggest the star is consuming a planet or even more there is an alternative but less likely scenario. The star could be stripping material from a nearby brown dwarf or giant planet. There's also a possibility that two gaseous planets could have collided, leading to the dust cloud.
"Stars live a very long time and this phase is very short-lived in the history of the star and the process of star formation," Pilachowski said.
"To catch a star in this act, I think is an amazing stroke of good luck."
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