SIMP-0136: Researchers find auroras on cosmic loner

Charged particles from space create beautiful light shows in the sky at high latitudes. However, such auroras do not only exist on Earth. A team of astronomers has discovered them on an unusual celestial body.

The team led by Evert Nasedkin from Trinity College Dublin in Ireland studied SIMP-0136 with the James Webb Space Telescope (JWST) and recorded strong auroral activity that heats up the upper atmosphere by 250 degrees Celsius. The team describes the discovery in the scientific journal Astronomy & Astrophysics.

SIMP-0136, actually SIMP J013656.5+093347, is an unbound object with planetary mass. This means that it does not orbit a star. It is located in the constellation of Pisces and is about 20 light years away from Earth.

SIMP-0136 rotates around its axis in 2.4 hours

The celestial body has about 1.2 times the radius of Jupiter and about 13 times its mass. This puts it on the borderline between a planet and a brown dwarf. It rotates around its axis in about 2.4 hours, whereby its brightness and temperature change.

Brown dwarfs are not stars, as no normal hydrogen fusion takes place in their interior. However, the pressure and temperature are sufficient for deuterium fusion. This also generates heat – on the surface of SIMP-0136 the temperature is around 1,500 degrees Celsius.

However, the researchers found significantly higher temperatures in the atmosphere of the celestial body. These are presumably “due to an energy input into the upper atmosphere by an aurora,” according to the paper.

Temperature changes of 5 degrees Celsius recorded

The discovery was made possible by the high sensitivity of the space telescope. This would have allowed them to detect temperature changes of less than 5 degrees Celsius. “These are the most precise measurements of the atmosphere of an extrasolar object ever made,” said Nasedkin. “It is the first time that changes in atmospheric properties have been measured directly.”

The researchers also found clouds in the atmosphere of the celestial body. However, these do not consist of water vapor as on Earth but of silicate grains – “similar to sand on the beach.”

Auroras in our solar system occur when charged particles emitted by the sun collide with the magnetic field of a planet. They occur not only on Earth but also on other planets, such as Mars, Jupiter, Saturn, or Neptune. As SIMP-0136 does not orbit a star, the auroras in its atmosphere are triggered by charged particles from interstellar space.

(wpl)