Astronomers Discover New Earth-Sized Planet Orbiting Jupiter-Sized Red Dwarf Star

Astronomers have discovered a new, Earth-sized planet that orbits an ultracool dwarf star similar in size to Jupiter, Guardian reported. This new extrasolar planet, or exoplanet, is named Speculoos-3b and is located relatively close to the Earth, just 55 light-years away. Meanwhile, the dwarf star is twice as cold as our Sun, as well as ten times less massive and a hundred times less luminous.

Speculoos-3b swings around the red dwarf once every 17 hours, making a year on the planet shorter than a single Earth day. This exoplanet is also likely "tidally locked" to its star, meaning it has an eternal dayside and an everlasting nightside.

Due to its short orbit, SPECULOOS-3b also receives almost times more energy per second than the Earth does from the Sun. 

"We believe that the planet rotates synchronously, so that the same side, called the day side, always faces the star, just like the moon does for the Earth. On the other hand, the night side would be locked in endless darkness," said Michael Gillon, an astronomer at the University of Liege in Belgium and lead author of the study.

Astronomer Michaël Gillon and the #SPECULOOS team discovered a new Earth-sized exoplanet around SPECULOOS-3, an "ultracool dwarf" star as small as Jupiter, twice as cold as our Sun, and located 55 light-years from Earth. #ULiège @NatureAstronomy @NASA https://t.co/2bQGJNhBmz pic.twitter.com/K0l9RBpbD6

— Université de Liège (@UniversiteLiege) May 15, 2024

The discovery, published in Nature Astronomy, was made by the SPECULOOS project, which is led by the University of Liege, in Belgium, in collaboration with the Universities of Birmingham, Cambridge, Bern, and the Massachusetts Institute of Technology. 

SPECULOOS (Search for Planets EClipsing ULtra-cOOl Stars) was established to search for exoplanets orbiting ultra-cool dwarf stars using a network of robotic telescopes based around the world.

Notably, ultra-cool red dwarf stars make up about 70% of the stars in our galaxy and survive for about 100 billion years. As per Space.com, red dwarfs have exceptionally long lifetimes because they are thousands of degrees cooler than the sun. 

''While ultracool dwarf stars are cooler and smaller than our Sun, their lifespan is over a hundred times longer — around 100 billion years — and they are expected to be the last stars still shining in the Universe. This long life span could offer opportunities for extraterrestrial life on orbiting planets to develop. The small size of ultracool dwarfs makes it easier to detect small planets,'' said the University of Birmingham's Professor Amaury Triaud.

''SPECULOOS-3b is special in that its stellar and planetary properties make it an optimal target for Webb, which is capable of getting information about the composition of the rocks that make its surface,'' Mr Triaud added.