A huge planetary mass object with a mysterious glow discovered beyond the solar system


Last February, astrophysicists used the microlens to discover planets outside our Milky Way for the first time. Now, astronomers using the National Science Foundation’s Karl G. Jansky Very large painting (VLA) did the very first radio telescope detection of a planet beyond our solar system.

VLA is the same tool used last year to measure magnetic field of a distant galaxy. Now the painting has revealed a planetary mass object more than a dozen times bigger than Jupiter with a mysterious auroral glow.

On the border between a planet and a brown dwarf

“This object is right on the border between a planet and a brown dwarf, or “a failing star”, and has surprises in store for us that can potentially help us understand the magnetic processes on stars and planets, “said Melodie Kao, head of the study. The question of where is the line between a brown dwarf and a massive planet has plagued astronomers for years.

Brown dwarfs are planetary bodies too large to classify as planets, but not massive enough to support the nuclear fusion of hydrogen that powers the stars. In 2001, VLA discovered the first signs of radio flaring in a brown dwarf, which led to further observations which confirmed that some of these bodies did indeed have strong auroras.

Scientists have yet to determine how these solitary objects could support the auroras, but have stipulated that they could be the result of an orbiting planet or moon interacting with the brown dwarf’s magnetic field. The newly discovered object, called SIMP J01365663 + 0933473, was found to have a magnetic field 200 times more powerful than that of Jupiter.

The planetary body was initially detected by VLA in 2016, but it was believed to be an old brown dwarf. Last year, an independent team of scientists discovered that the object was actually part of a very young group of stars, which means it could have been much larger.

Deuterium combustion limit reached

The new data revealed that the body was 12.7 times more massive than Jupiter. The information would indicate that SIMP J01365663 + 0933473 meets the “deuterium burn limit”, a term used to describe a planetary mass below which deuterium melting ceases, measured at about 13 masses from Jupiter.

This limit is one of the criteria that astronomers use to differentiate a brown dwarf from a massive planet. “When it was announced that SIMP J01365663 + 0933473 had a mass near the deuterium burn limit, I had just finished analyzing its latest VLA data,” Kao said.

In addition to providing the first radio detection of the object’s magnetic field, VLA also provided the first measurement of the field. TThe Caltech team that initially detected the radio broadcast of SIMP J01365663 + 0933473 in 2016 confirmed that the field was even stronger than expected.

This revelation “presents enormous challenges to our understanding of the dynamo mechanism that produces magnetic fields in brown dwarfs and exoplanets and helps drive the auroras we see,” said Gregg Hallinan, of Caltech. Hallinan added that the discovery of the object through its auroral radio broadcast means that VLA can now provide “a new way to detect exoplanets, including elusive thugs that do not orbit a parent star.”


Arline J. Mercier