May 25, 2017 I Paul Seaburn

Orphan Planet Acting Mysteriously Like a Star

Do planets have feelings? Can they hear astronomers talking about them … giving them derogatory names like “rogue” … referring to them as orphans, wandering or starless without knowing anything about their history or how they came to be in the non-solar-system state they seem to be in? A new study of a so-called orphan planet refers to it as “lonely” – could this be why it is suddenly acting like a brown dwarf or a young star? What is the medical term for “anthropomorphism about planets” and is there a treatment? Asking for a friend.

A group of astronomers from the University of Valparaiso and the Max Planck Institute for Astronomy, led by Amelia Bayo of Valparaiso, have been using the the ALMA observatory in Chile to study OTS44 -- a free-floating planetary-mass object discovered in 1998 and currently located 550 light-years away in the constellation Chamaeleon. OTS44 is approximately 11.5 times the mass of Jupiter and is the smallest and least massive known free-floating planet. On the plus side, it’s one of only four known to have an orbiting disc. However, according to Bayo’s study published in the Astrophysical Journal Letters, the disc is much different that that of Saturn or other ringed planets, hinting that OTS44 may not be a planet at all.

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Artists' impression of the disk around OTS44.Image: Johan Olofsson (U Valparaiso & MPIA)

Bayo’s analysis shows that the mass of the disk is, well, massive, and its ratio of mass of disc to mass of orbited object is closer to that of a substellar object like a brown dwarf or a young star in the process of forming a planetary solar system. The study also found that OTS44 appears to be pulling in dust and rocks from the disc, causing it to grow – not very planetary behavior. Finally, the astronomers discovered that the dust particles themselves are clumping together and growing, suggesting that they may be forming moons or – if OTS44 is a young star – planets.

Is this a big deal? Yes, says an excited Bayo.

The more we know about OTS44, the greater its similarities with a young star. But its mass is so low that theory tells us it cannot have formed like a star!

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Saturn acting like a ringed planet

And yet, the study shows that this process formed … something. Whatever it is, it’s obviously impressive enough to Amelia Bayo and her fellow astronomers to revise their models on both planetary and star formation. So, what should it be called? A big brown dwarf with a belt? Ringed and roaming? Lonely no more?

Any word on that cure for planetary anthropomorphism?

Paul Seaburn

Paul Seaburn is the editor at Mysterious Universe and its most prolific writer. He’s written for TV shows such as "The Tonight Show", "Politically Incorrect" and an award-winning children’s program. He's been published in “The New York Times" and "Huffington Post” and has co-authored numerous collections of trivia, puzzles and humor. His “What in the World!” podcast is a fun look at the latest weird and paranormal news, strange sports stories and odd trivia. Paul likes to add a bit of humor to each MU post he crafts. After all, the mysterious doesn't always have to be serious.

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