An Earth-sized Exoplanet Found Orbiting A Jupiter-Sized Star

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Astronomers examined one red dwarf star named SPECULOOS-3, a Jupiter-sized star about 55 light-years away, and found an Earth-sized exoplanet orbiting it. It's an excellent candidate for further study with the James Webb Space Telescope.

SPECULOOS stands for the Search for habitable Planets EClipsing ULtra-cOOl Stars . It's a European Southern Observatory effort that searches for terrestrial planets orbiting cool stars like red dwarfs. (Its odd name is an homage to a Belgian sweet biscuit.) Its goal is to find planets that are good targets for spectroscopy with the JWST and the ELT .

The new planet is named SPECULOOS-3b, and its discovery was presented in a recent paper in Nature Astronomy. The paper is titled ⁘ Detection of an Earth-sized exoplanet orbiting the nearby ultracool dwarf star SPECULOOS-3. ⁘ The lead author is Michaël Gillon from the Astrobiology Research Unit, Université de Liège, Belgium.

SPECULOOS is an automated search using four telescopes around the world: one at the Paranal Observatory in Chile, one at the Teide Observatory in Tenerife, one at the La Silla Observatory in Chile, and one at the Oukaïmden Observatory in Morocco. The project is searching 1,000 ultra-cool stars and brown dwarfs for terrestrial planets.

One of the problems in detecting planets around these stars is their low luminosity. Since they're so dim, transiting exoplanets are difficult to detect, making their planetary populations difficult to characterize and study. So far, astronomers have found only one planetary system around one of these stars, and it's rather well-known: the TRAPPIST-1 system. When it began, the SPECULOOS program expected to find at least one dozen systems similar to TRAPPIST-1.