Are there stars without orbiting planets?

Aurora outside the solar system

Astronomers discovered the first aurora from a celestial body outside the solar system. This luminous phenomenon is comparable to the northern lights on earth, but 10,000 times stronger than anything seen so far. The researchers have published their results in the journal "Nature".

Aurora from LSR J1835 + 3259

If charged particles penetrate the magnetic field of a planet, the particles are directed to the poles within the magnetosphere and there collide with gas atoms in the atmosphere. The resulting bright emissions are called aurora. So far, astronomers have only observed such luminous phenomena within our solar system and only on planets.

However, an international team of researchers has now been able to demonstrate this phenomenon in a dwarf star about 18.5 light years away. To do this, they carried out parallel measurements of radio waves and visible light with telescopes on Earth. The data suggest that the bright features observed on the surface of the celestial body are triggered by electrons striking the hydrogen-containing atmosphere. This creates an aurora that is characteristic of planets.

LSRJ1835 + 3259, the catalog name of the examined object, is a dwarf star - on the border with the brown dwarf. The latter have too much mass to be classified as planets, but too little to be considered a real star. That is why they are also known as failed stars. Their mass is between 13 and 75 times the mass of Jupiter.

The new observations make researchers doubt the previous interpretation that brown dwarfs only just missed the status of a star. "Brown dwarfs are somewhere between stars and planets and these results are proof that we should see brown dwarfs less as failed stars and more as oversized planets," says Stuart Littlefair from the research team.

The fact that the team has observed an aurora outside the solar system is also important for the search for other exoplanets. Up until now, giant planets in the distance, which, like Jupiter or Saturn, orbit their central star in wide orbits, have been difficult to find. Conventional search methods work best for planets in tight orbits. Large planets in particular could be identified by the radio radiation of their intense aurora.