“With an extremely close orbit that only takes 11 hours to complete, this “hot Jupiter” – a term for hot planets with large masses and short orbital periods – looks to be engaged in a drawn-out death spiral”. It’s possible that PTFO 8-8695 b formed farther out in the solar system and somehow got knocked or pulled closer to its sun – which could explain how such a large planet exists so close to a star.
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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. To date, astronomers have detected more than 3,300 exoplanets, the majority of them orbiting middle-aged stars like our sun. This suggested that a planet was crossing in front of the star, briefly blocking some of its light from Earth’s view. It’s so close to the star that it whizzes round its orbit in less than a day. However, young PTFO8-8695 b and its early decaying condition indicated that it is something unique and special.
In fact, it’s one of the youngest planets ever discovered. 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.
These are giant exoplanets that orbit close to their parent stars and are also known as roaster planets, they orbit their stars in a short time and can be easily observed in transit. “Light curves and variations of this star presented an intriguing technique to confirm or refute such a planet”. That meant we wouldn’t have to come back night after night after night, year after year after year. So that’s what we did. “We’ll keep looking at this star”.
A spectroscopic analysis of the light coming from the star revealed excess emission in the H-alpha spectral line, a type of light emitted from highly energised hydrogen atoms.
“We saw one component of the hydrogen emission start on one side of the star’s emission and then move over to the other side”, Prato said. And because young stars are also relatively active – with strong magnetic fields, and producing frequent visual outbursts and dimmings – it makes it harder for researchers to accurately gauge whether they’re orbited by planets. So there was some skepticism that a planet had really been found.
“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.
According to the Rice University researchers who led the study, it’s an extreme case of an “evaporating hot Jupiter”. “Does it eventually stop losing mass, or does it keep going until it falls into the star?”
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And that list of planets observed is growing all the time.
