spaceSpace and Physics

How Big Planets Form Quickly Around Small Stars


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockJan 23 2020, 18:23 UTC

Artist's impression of a gas giant exoplanet near a red dwarf star. Alberto Laratro/Shutterstock

A new paper has come up with a novel model for the mystery of how giant planets form around red dwarfs – stars much smaller than the Sun. The idea is not at all what’s expected from standard planetary formation models. 

All stars form in giant clouds of material. Once they form, their light pushes this material away. Big stars have a lot of material around them – there's so much that it takes a long time to disperse. While that works for giant planets, which have time to form slowly out of all the star's material over millions of years, red dwarfs haven't got that much material around them to begin with. Finding red dwarfs, therefore, with giant planets nearby was a bit of a puzzle.

To try and solve this question, researchers from the University of Central Lancashire used a supercomputer to simulate what planets can form around red dwarfs. As reported in Astronomy & Astrophysics, they found that giant planets can still not only form around red dwarfs, they can do so in a manner similar to other giant planets. They just did so more quickly, with the red dwarfs ridding themselves of material faster. In fact, the formation can happen in a matter of a few thousand years, a blink of an eye in cosmic terms. 

“The fact that planets may be able to form on such short timescale around tiny stars is incredibly exciting. Our work shows that planet formation is particularly robust: other worlds can form even around small stars in a variety of ways, and therefore planets may be more diverse than we previously thought,” lead author Dr Anthony Mercer said in a statement.


In the last decade, red dwarfs have become an important focus in the search for exoplanets. As the most common type of stars, researchers have discovered that they are orbited by a wide range of bodies, from Earth-sized planets like in the case of TRAPPIST-1 to gas giants 10 times the mass of Jupiter.

“This was the first time that we were able not only to see planets forming in computer simulations but also to determine their initial properties with great detail. It was fascinating to find that these planets are of the ‘fast and furious’ kind – they form quickly and they are unexpectedly hot,” co-author Dr Dimitris Stamatellos.

The team believes the heat signatures of these planets will be visible to some of the upcoming telescopes, which they hope to test soon when they are constructed.

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