Three Earth-sized planets found in a surprising double-star system

For a long time, scientists believed that planets didn’t really stand a chance in double-star systems.

Two stars pulling on each other with intense gravity seemed like a recipe for chaos – not the kind of place where planets could peacefully orbit.

Yet new research reveals that even in this cosmic turmoil, Earth-sized worlds can quietly thrive.

A team of astronomers has found not one, but three Earth-sized planets in a binary star system located about 190 light-years away from Earth.

Two stars, three planets

TOI-2267 is not your average star system. It’s a compact binary, which means its two stars orbit each other closely.

Systems like this usually aren’t great places for planets. The two stars pull on each other with gravitational forces that make it tough for planets to form. And if they do form, they are unlikely to stay in stable orbits.

But in this case, researchers found a rare setup, according to Sebastián Zúñiga-Fernández, a member of the ExoTIC group at the University of Liège (ULiège).

“Our analysis shows a unique planetary arrangement: two planets are transiting one star, and the third is transiting its companion star,” said Zúñiga-Fernández.

“This makes TOI-2267 the first binary system known to host transiting planets around both of its stars.”

Discovery of the double-star system

The planets are all Earth-sized and orbit their stars fairly quickly. The setup breaks a lot of expectations.

“Our discovery breaks several records, as it is the most compact and coldest pair of stars with planets known, and it is also the first in which planets have been recorded transiting around both components,” noted study co-author Francisco J. Pozuelos.

The discovery started with data from NASA’s TESS space telescope, which looks for exoplanets by tracking slight dips in starlight.

The tiny anomalies usually mean a planet is crossing in front of its star. This is how scientists first noticed signs of two planets in the TOI-2267 system.

The team spotted the signals early using their own software, SHERLOCK. That early detection gave the researchers a head start in organizing follow-up observations from Earth.

To lock in the discovery, they turned to robotic telescopes like SPECULOOS and TRAPPIST. These instruments are designed to focus on faint, cool stars – exactly the kind of stars where small, rocky planets tend to hide.

Rocky planets in extreme conditions

Double-star systems aren’t rare. In fact, about half of all Sun-like stars in the galaxy are in binary or multiple star systems.

That’s what makes this discovery so significant. Finding Earth-sized planets in a system like TOI-2267 raises fresh questions – and exciting possibilities.

“Discovering three Earth-sized planets in such a compact binary system is a unique opportunity,” said Zúñiga-Fernández.

“It allows us to test the limits of planet formation models in complex environments and to better understand the diversity of possible planetary architectures in our galaxy.”

According to Pozuelos, the system is a natural laboratory for understanding how rocky planets can emerge and survive under extreme dynamical conditions, where we previously thought their stability would be compromised.

Observations of the double-star system

The three planets in TOI-2267 are too far away to visit, but astronomers are already lining up future observations.

The James Webb Space Telescope and powerful new ground-based telescopes could help measure the planets’ masses and densities. Some may even be able to look for signs of atmospheres.

This type of discovery demonstrates what is possible when space telescopes such as TESS collaborate with ground-based equipment such as SPECULOOS and TRAPPIST.

Together, they’re helping scientists look deeper into the galaxy – and find surprises in places few thought to check.

Scientists are now eager to investigate whether these planets have atmospheres – clues that could reveal their makeup and how they formed in such harsh conditions.

Each new detail helps piece together where different kinds of worlds can truly survive.

The full study was published in the journal Astronomy and Astrophysics.

Image details: An artist’s impression of the binary stellar system TOI-2267. Image credit: Mario Sucerquia, University of Grenoble Alpes.

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