VLA detects possible extrasolar planetary-mass magnetic powerhouse

August 3, 2018, National Radio Astronomy Observatory
Credit: Chuck Carter, NRAO/AUI/NSF

Astronomers using the National Science Foundation's Karl G. Jansky Very Large Array (VLA) have made the first radio-telescope detection of a planetary-mass object beyond our Solar System. The object, about a dozen times more massive than Jupiter, is a surprisingly strong magnetic powerhouse and a "rogue," traveling through space unaccompanied by any parent star.

"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 Melodie Kao, who led this study while a graduate student at Caltech, and is now a Hubble Postdoctoral Fellow at Arizona State University.

Brown dwarfs are objects too massive to be considered planets, yet not massive enough to sustain nuclear fusion of hydrogen in their cores—the process that powers stars. Theorists suggested in the 1960s that such objects would exist, but the first one was not discovered until 1995. They originally were thought to not emit radio waves, but in 2001 a VLA discovery of radio flaring in one revealed strong magnetic activity.

Subsequent observations showed that some brown dwarfs have strong auroras, similar to those seen in our own Solar System's giant planets. The auroras seen on Earth are caused by our planet's magnetic field interacting with the solar wind. However, solitary brown dwarfs do not have a solar wind from a nearby star to interact with. How the auroras are caused in brown dwarfs is unclear, but the scientists think one possibility is an orbiting planet or moon interacting with the brown dwarf's magnetic field, such as what happens between Jupiter and its moon Io.

The strange object in the latest study, called SIMP J01365663+0933473, has a magnetic field more than 200 times stronger than Jupiter's. The object was originally detected in 2016 as one of five brown dwarfs the scientists studied with the VLA to gain new knowledge about magnetic fields and the mechanisms by which some of the coolest such objects can produce strong radio emission. Brown dwarf masses are notoriously difficult to measure, and at the time, the object was thought to be an old and much more massive brown dwarf.

Last year, an independent team of scientists discovered that SIMP J01365663+0933473 was part of a very young group of stars. Its young age meant that it was in fact so much less massive that it could be a free-floating planet—only 12.7 times more massive than Jupiter, with a radius 1.22 times that of Jupiter. At 200 million years old and 20 light-years from Earth, the object has a surface temperature of about 825 degrees Celsius, or more than 1500 degrees Farenheit. By comparison, the Sun's surface temperature is about 5,500 degrees Celsius.

The difference between a gas giant planet and a brown dwarf remains hotly debated among astronomers, but one rule of thumb that astronomers use is the mass below which deuterium fusion ceases, known as the "deuterium-burning limit", around 13 Jupiter masses.

Simultaneously, the Caltech team that originally detected its radio emission in 2016 had observed it again in a new study at even higher radio frequencies and confirmed that its magnetic field was even stronger than first measured.

"When it was announced that SIMP J01365663+0933473 had a mass near the deuterium-burning limit, I had just finished analyzing its newest VLA data," said Kao.

The VLA observations provided both the first radio detection and the first measurement of the magnetic field of a possible planetary mass object beyond our Solar System.

Such a strong "presents huge challenges to our understanding of the dynamo mechanism that produces the magnetic fields in brown dwarfs and exoplanets and helps drive the auroras we see," said Gregg Hallinan, of Caltech.

"This particular object is exciting because studying its magnetic dynamo mechanisms can give us new insights on how the same type of mechanisms can operate in extrasolar planets—planets beyond our Solar System. We think these mechanisms can work not only in , but also in both gas giant and terrestrial planets," Kao said.

"Detecting SIMP J01365663+0933473 with the VLA through its auroral emission also means that we may have a new way of detecting exoplanets, including the elusive rogue ones not orbiting a parent star," Hallinan said.

Explore further: Brown dwarf in a dynamical-tide regime detected by WASP survey

More information: Melodie M. Kao et al, The Strongest Magnetic Fields on the Coolest Brown Dwarfs, The Astrophysical Journal Supplement Series (2018). DOI: 10.3847/1538-4365/aac2d5

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4.3 / 5 (11) Aug 03, 2018
Exciting! Nothing like another type of observation possibly confirming Jupiter sized planets, and free floating at that.
2.5 / 5 (8) Aug 03, 2018
"Such a strong magnetic field 'presents huge challenges to our understanding of the dynamo mechanism that produces the magnetic fields in brown dwarfs and exoplanets and helps drive the auroras we see,'"

I just want to bring light to another "surprise" involving a largely speculated, impossible to directly observe mechanism (dynamo theory).
It doesn't work with this gas giant/brown dwarf and presents the possibility that we took our understanding of dynamos for granted, involved them where they shouldn't be and haven't looked back (because we didn't need to until now).

"We think these mechanisms can work not only in brown dwarfs, but also in both gas giant and terrestrial planets,"

I think a similar argument can be made for a variety of astrophysical phenomena we observe.
Aug 03, 2018
This comment has been removed by a moderator.
3 / 5 (6) Aug 03, 2018
It's beautiful - all decked out like a Christmas tree ornament.

must be ET
says Anonym

If ET lives there, they must be gigantic. But it's a failed Star... a rogue and a flyby. Hoping that it won't become like the white ball on a pool table.
5 / 5 (8) Aug 03, 2018
The strange object in the latest study, called SIMP J01365663+0933473, has a magnetic field more than 200 times stronger than Jupiter's.

Earth's magnetic field .............= ~50uT
Jupiter's field = 20,000 * 50uT = ~1T
Wierdo planet field = 200 * 1T = ~200T

Insane! The sheer amount of energy contained in a field of such strength, with such an immense volume... it's absolutely mind boggling.
5 / 5 (3) Aug 03, 2018
I will want to check DrudgeReport to see if the news of this failed Star has been disseminated to the masses. t b g larsson is right. This IS exciting news. It is a great time to be alive.
That and news of the next crop of astronauts in training.
A globe that size is scary, plus the fact that it isn't corralled - doubly scary.
5 / 5 (5) Aug 03, 2018

Such good pure science coming out of a facility that was completed under budget and on time, funded by taxpayers.

5 / 5 (3) Aug 03, 2018
No. Nothing on Drudge about the monster.

But I watched this and enjoyed it.
War games - American style

5 / 5 (3) Aug 03, 2018
Here's another with Neil DeGrasse Tyson:

5 / 5 (2) Aug 05, 2018
I have to suspect that such a huge magnetic field limits the motions of ions inside the object to one dimensional spiraling around magnetic field lines. Is this enough to maintain deuterium burning? Is it enough for carbon cycle? I think that drawing the line between brown dwarfs and planets based solely on mass may be misclassifying SIMP J01365663+0933473.
3 / 5 (1) Aug 07, 2018
There are likely more of these failed stars in our galaxy than stars we are aware of. Whether it is captured by the gravity another star and becomes a "planet" is inconsequential.

In fact, visible stars may be much rarer than these failed stars that litter the universe. That's a lot of mass we're not taking into account.
5 / 5 (1) Aug 09, 2018
mag field of 200T, simply amazing
2.3 / 5 (3) Aug 25, 2018
The discovery of this object represents a total failure of the standard guesswork, and further confirmation of an electric viewpoint.
5 / 5 (1) Aug 26, 2018
The discovery of this object represents a total failure of the standard guesswork, and further confirmation of an electric viewpoint.

If you mean EU. Why would it?

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