Gaia Just Found Two Massive Objects That Shouldn't Exist - And Astronomers Are Stunned

By European Space Agency (ESA)February 7, 2025
7 Mins Read



This is an artist impression of the exoplanet Gaia-4b and the brown dwarf Gaia-5b, which were both discovered by ESA’s Gaia mission. This artist impression visualises a portion of the orbital motions as determined by Gaia’s astrometric data. The stars and planets are not to scale. Credit: ESA/Gaia/DPAC/M. Marcussen

Scientists using data from the European Space Agency’s Gaia mission have made a groundbreaking discovery: a massive exoplanet and a brown dwarf.



This marks the first time a planet has been identified solely through Gaia’s ability to detect the tiny gravitational “wobble” it causes in its host star. What makes this finding even more intriguing is that both objects orbit low-mass stars—an arrangement considered extremely rare. These unexpected discoveries are challenging our understanding of how planets and brown dwarfs form and evolve.

Gaia Reveals Two New Mysterious Celestial Objects
New research published on February 4 confirms the existence of two mysterious celestial objects using data from ESA’s Gaia spacecraft. The first, Gaia-4b, is a massive “Super-Jupiter” exoplanet, while the second, Gaia-5b, is a brown dwarf. Surprisingly, both of these giant objects orbit low-mass stars, challenging current models of planetary formation.



Exoplanet Gaia 4b
Gaia-4b is a planet orbiting the star called Gaia-4, around 244 light-years away. Gaia-4b is about twelve times more massive than Jupiter. With an orbital period of 570 days, it is a relatively cold gas giant planet. This artist’s impression visualizes a portion of the orbital motion as determined by Gaia’s astrometric data. The star and planet are not to scale. Credit: ESA/Gaia/DPAC/M. Marcussen

Gaia-4b orbits the previously unremarkable star Gaia-4, located about 244 light-years from Earth. Meanwhile, Gaia-5b circles Gaia-5, a star roughly 134 light-years away. These discoveries place them relatively close to us in cosmic terms, right within our galactic neighborhood. Their unexpected nature raises new questions about how such massive objects form around smaller stars. Gaia’s ongoing mission will provide critical data to help scientists better understand these puzzling systems.

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