A new Earth-sized planet has been discovered orbiting a star that will live for 100 billion years

Using global robotic telescopes, researchers have discovered the Earth-sized planet SPECULOOS-3, orbiting an ultracool red dwarf in Milky Way. This planet, tidally locked and likely lacking an atmosphere due to intense radiation, offers a new look at long-lived red dwarfs that are thought to be among the last stars burning in the universe.

Our galaxy is a treasure trove of red stars. In fact, more than 70% of the stars in the Milky Way are M dwarfs, also known as red dwarfs. These stars are cool and faint compared to our Sun, but often orbit exoplanets with high-energy radiation, especially at an early age. And those ”lives” last a long time. Stars like our Sun burn for about 10 billion years before turning into hungry red giants that devour any planets too close. M dwarfs have been burning for 100 billion years or longer, possibly offering a support for life and an even longer window for life to develop.

An international team using robotic telescopes around the world recently spotted an Earth-sized planet orbiting an ultracool red dwarf star, the darkest and longest living star. When the universe cools and darkens, these will be the last burning stars.

Discovery

The exoplanet SPECULOOS-3 b is about 55 light-years from Earth (really close when you consider the cosmic scale!) and almost the same size. One orbit around the star takes about 17 hours in a year there. But the days and nights may never end: The planet is thought to be tidally locked, so that the same side, known as the day side, always faces the star, as the Moon does to the Earth. The night side would be enclosed in endless darkness.

Survey of ultracold dwarfs

Ultracool dwarf stars are ubiquitous in our corner of the galaxy. They are so faint that their planetary population is largely unexplored. The SPECULOOS (Search for Planets EClipsing ULTra-cOOl Stars) project led by Michael Gillon at the University of Liège in Belgium was to change that. Ultracool dwarf stars are scattered across the sky, so you have to observe them one by one for weeks to have a good chance of detecting transiting planets. For this you need a specialized network of professional telescopes. That’s the SPECULOOS concept.

”We designed SPECULOOS specifically to survey nearby ultracool dwarf stars in search of rocky planets,” Gillon said. ”With the prototype SPECULOOS and essential help NASA We discovered the famous TRAPPIST-1 system with the Spitzer Space Telescope. That was a great start!”

Gillon is the lead author of the paper announcing the planet’s discovery, published on May 15, 2024 in Astronomy of nature. The project is a truly international effort with partnerships with the universities of Cambridge, Birmingham, Bern, Massachusetts Institute of Technology and ETH Zürich.

The star SPECULOOS-3 is thousands of degrees cooler than our Sun, with an average temperature of about 4,760 F (2,627 C), but it blasts its planet with radiation, meaning it likely has no atmosphere.

Seeing a star, let alone a planet, is a feat in itself. “Although this particular red dwarf is more than a thousand times fainter than the Sun, its planet orbits much, much closer than Earth and heats the planetary surface,” said co-author Catherine Clark, a postdoctoral fellow at NASA’s Jet Propulsion Laboratory. in Southern California.

Fun facts

• While the planet is about the same size as Earth, its star is only slightly larger than Jupiter – but much more massive.
• The planet receives almost 16 times more energy per second than Earth receives from the Sun.
• Have you caught a cookie connection? The SPECULOOS planet-hunting program shares its name with spiced shortbread. Both are from Belgium. Candy!

Next steps

SPECULOOS-3 b is an excellent candidate for follow-up observations by the James Webb Space Telescope. Not only could we learn about the potential of the atmosphere and surface mineralogy, but it could also help us understand the stellar neighborhood and our place in it.

”We are making great progress in our study of planets orbiting other stars. We have now reached the stage where we can detect and study Earth-sized exoplanets in detail. The next step will be to determine whether any of them are habitable or even inhabited,” said Steve B. Howell, one of the planet’s discoverers at NASA’s Ames Research Center in Silicon Valley.

More about this discovery:

Reference: “Detection of an Earth-sized exoplanet orbiting a nearby ultracool dwarf star SPECULOOS-3” by Michaël Gillon, Peter P. Pedersen, Benjamin V. Rackham, Georgina Dransfield, Elsa Ducrot, Khalid Barkaoui, Artema Y. Burdanova, Urs Schroffenegger, Yilen Gómez Maqueo Chew, Susan M. Lederer, Roi Alonso, Adam J. Burgasser, Steve B. Howell, Norio Narita, Julien de Wit, Brice-Olivier Demory, Didier Queloz, Amaury HMJ Triaud, Laetitia Delrez, Emmanuël Jehin, Matthew J .Hooton, Lionel J. Garcia, Clàudia Jano Muñoz, Catriona A. Murray, Francisco J. Pozuelos, Daniel Sebastian, Mathilde Timmermans, Samantha J. Thompson, Sebastián Zúñiga-Fernández, Jesús Aceituno, Christian Aganze, Pedro J. Thomas Baycroft, Zouhair Benkhaldoun, David Berardo, Emeline Bolmont, Catherine A. Clark, Yasmin T. Davis, Fatemeh Davoudi, Zoë L. de Beurs, Jerome P. de Leon, Masahiro Ikoma, Kai Ikuta, Keisuke Isogai, Izuru Fukuda, Izuru Fukuda, Fukui , Roman Gerasimov, Mourad Ghachoui, Maximilian N. Günther, Samantha Hasler, Yuya Hayashi, Kevin Heng, Renyu Hu, Taiki Kgetani, Yugo Kawai, Kiyoe Kawauchi, Daniel Kitzmann, Daniel DB Koll, Monika Lendl, John H. Livingston, Xintong Lyu , Erik A. Meier Valdés, Mayuko Mori, James J. McCormac, Felipe Murgas, Prajwal Niraula, Enric Pallé, Ilse Plauchu-Frayn, Rafael Rebolo, Laurence Sabin, Yannick Schackey, Nicole Schanche, Franck Selsis, Alfredo Sota, Manu Stalport , Matthew R. Standing, Keivan G. Stassun, Motohide Tamura, Yuka Terada, Christopher A. Theissen, Martin Turbet, Valérie Van Grootel, Roberto Varas, Noriharu Watanabe, and Francis Zong Lang, 15 May 2024, Astronomy of nature.
DOI: 10.1038/s41550-024-02271-2