New Earth-sized planet discovered orbiting a star that will live for 100 billion years

Researchers using global robotic telescopes have discovered an Earth-sized planet, SPECULOOS-3 b, orbiting an ultracool red dwarf. Milky Way. This planet, which is confined and likely has no atmosphere due to its intense radiation, offers new insights into long-lived red dwarfs, which are expected to be among the last burning stars in the universe.

Our Milky Way is a treasure trove of red stars. In fact, more than 70% of the stars in the Milky Way are M dwarfs, also called red dwarfs. These stars are cool and dim compared to our Sun, but they often blast orbiting exoplanets with high-energy radiation, especially early in their lives. And those ”lives” last one long time. Stars like our Sun burn for about 10 billion years before turning into hungry red giants that devour any planets that are too close. M dwarfs continue to burn for 100 billion years or more, perhaps providing a foothold for life, and an even longer period for life to evolve.

An international team using robotic telescopes around the world recently discovered an Earth-sized planet orbiting an ultra-cool red dwarf, the faintest and longest-lived star. When the universe turns cold and dark, these will be the last burning stars.

The discovery

The exoplanet SPECULOOS-3 b is located about 55 light-years from Earth (very close if you consider the cosmic scale!) and almost the same size. A year there, one orbit around the star, takes about 17 hours. However, the days and nights may never end: the planet is thought to be tidally locked, so the same side, known as the day side, always faces the star, like the moon faces Earth. The night side would be locked in endless darkness.

Exploration of ultra-cool dwarves

In our corner of the Milky Way, ultra-cool dwarf stars are ubiquitous. They are so weak that their planetary population is largely unexplored. The SPECULOOS (Search for Planets EClipsing ULTra-cOOl Stars) project, led by Michael Gillon of the University of Liège, Belgium, aimed to change that. Ultracool dwarf stars are scattered across the sky, so you have to observe them one at a time for weeks to get a good chance of detecting transiting planets. For this you need a special network of professional telescopes. This is the concept of SPECULOOS.

“We designed SPECULOOS specifically to explore nearby ultra-cool dwarf stars in search of rocky planets,” Gillon said. ”With the SPECULOOS prototype and the crucial help of the NASA Spitzer space telescope we discovered the famous TRAPPIST-1 system. That was an excellent start!”

Gillon is the lead author of the paper announcing the planet’s discovery, published May 15, 2024 in Nature Astronomy. The project is a truly international undertaking, in collaboration with the universities of Cambridge, Birmingham, Bern, Massachusetts Institute of Technology and ETH Zurich.

The SPECULOOS-3 star is thousands of degrees cooler than our sun, with an average temperature of about 2,627 degrees Celsius, but it’s bombarding its planet with radiation, meaning it likely has no atmosphere.

Seeing the star, let alone the 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, warming the planetary surface,” said co-author Catherine Clark, a postdoctoral researcher at the Jet Propulsion Laboratory from NASA. in Southern California.

Fun facts

• Although the planet is about the same size as Earth, the star is slightly larger than Earth Jupiter – but much more massive.
• The planet receives almost 16 times more energy per second than Earth receives from the sun.
• Did you notice the cookie connection? The planet search program SPECULOOS shares its name with the spiced shortbread. Both are from Belgium. Sweet!

The next steps

SPECULOOS-3 b is an excellent candidate for follow-up observations with the James Webb Space Telescope. Not only can we learn about the potential of an atmosphere and the mineralogy of its surface, but it can 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 if any of these are habitable or even inhabited,” said Steve B. Howell, one of the planet’s discoverers at NASA Ames Research Center in Silicon Valley.

For more information about this discovery:

Reference: “Detection of an Earth-sized exoplanet orbiting the nearby ultra-cool dwarf star SPECULOOS-3” by Michaël Gillon, Peter P. Pedersen, Benjamin V. Rackham, Georgina Dransfield, Elsa Ducrot, Khalid Barkaoui, Artem Y. Burdanov , 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 . Amado, 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, Akihiko Fukui, Roman Gerasimov, Mourad Ghachoui, Maximilian N. Günther, Samantha Hasler, Yuya Hayashi, Kevin Heng, Renyu Hu, Taiki Kagetani, Yugo Kawai, Kiyoe Kawauchi, Daniel Kitzmann, Daniel DB Koll, Monika Lendl, John H. Livingston, , 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, May 15, 2024, Nature Astronomy.
DOI: 10.1038/s41550-024-02271-2