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A bizarre rogue planet without a star is roaming the Milky Way just 20 light-years from Earth. And according to a recently published study in The Astrophysical Journal, this strange, nomadic world has an incredibly powerful magnetic field that is some 4 million times stronger than Earth's, which generates spectacular auroras that would put our northern lights to shame.
The new observations, made with the National Science Foundation's Karl G. Jansky Very Large Array (VLA), provide not only the first radio detection of a planetary mass object beyond our solar system, but also mark the first time researchers have measured the magnetic field of such a body.
[...] The peculiar and untethered object, succinctly named SIMP J01365663+0933473 (we'll call it SIMP for simplicity's sake), was first discovered back in 2016. At the time, researchers thought SIMP was a brown dwarf: an object that's too big to be a planet, but too small to be a star. However, last year, another study showed that SIMP is just small enough, at 12.7 times the mass and 1.2 times the radius of Jupiter, to be considered a planet — albeit a mammoth one.
"This object is right at the boundary between a planet and a brown dwarf, or 'failed star,' and is giving us some surprises that can potentially help us understand magnetic processes on both stars and planets," said Arizona State University's Melodie Kao, who led the new study on SIMP, in a press release.
[...] SIMP seems to be a massive and magnetic exoplanet without a star that may have a moon that is generating brilliant auroras while wandering the Milky Way.
[...] "Detecting SIMP J01365663+0933473 with the VLA through its auroral radio emission also means that we may have a new way of detecting exoplanets, including the elusive rogue ones not orbiting a parent star," said co-author Gregg Hallinan of Caltech.
http://www.astronomy.com/news/2018/08/free-range-planet
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(Score: 1) by nitehawk214 on Monday August 06 2018, @03:05PM (1 child)
So, we know about brown dwarf sized "failed star" planets, but is it possible to have Earth or even Jupiter sized rouge planets? Or do planetary sized bodies need to form in the presence of a larger gravity well, then get kicked out for various regions?
Perhaps this aurora-detection technique will allow us to detect increasingly smaller rogue planets.
"Don't you ever miss the days when you used to be nostalgic?" -Loiosh
(Score: 4, Informative) by takyon on Monday August 06 2018, @03:34PM
Rogue planets are hard to detect because they typically have extremely low temperatures and brightnesses.
https://en.wikipedia.org/wiki/Rogue_planet#Known_or_possible_rogue_planets [wikipedia.org]
Most of the known ones are closer to being brown dwarfs, but it looks like PSO J318.5-22 [wikipedia.org] is an honest rogue planet at only 6.5 Jupiter masses. It was only found due to it being young and hot. ( ͡° ͜ʖ ͡°)
The rogue planets may be ejected from a star system or form on their own (possibly only the sub-brown dwarf ones). I don't think the definition of "rogue planet" should include anything about the origin.
We'll need much better telescopes, or possibly dumb luck, in order to find Jupiter, Neptune, or Earth-mass rogue planets. Maybe there are some objects like that in our vicinity (1-5 light years) and we don't even know it. After all, Luhman 16 is a binary brown dwarf only 6.5 light years away, and the discovered was announced in 2013.
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