3 Earth-sized exoplanets may have Star Wars-like double sunsets, researchers find

The team received their initial indications regarding these three remote Earth-like planets when they analysed data from Nasa’s planet-hunting spacecraft TESS.

One of the exoplanets orbiting the two “failed stars”, about 120 light-years away from Earth, is similar to the legendary desert planet Tatooine from Star Wars, which is well-known for its double sunsets. (AI-generated image: DALLE)

Astronomers have found three Earth-sized exoplanets around twin stars using the US-based National Aeronautics and Space Administration’s (Nasa) planet-hunting spacecraft TESS. This finding could change our understanding of planet formation and the stability of worlds after formation, as binary systems had been hypothesised to be inhospitable to the formation of intricate planetary configurations.

The encounter is made even more intriguing by the fact that the planets of TOI-2267 also break some exoplanet records.

There are many different sizes, forms, and configurations of binary star systems. TOI-2267 is a “compact binary”. This indicates that the stars that make up this system revolve around one another quite closely.

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Discovery breaks several records

A researcher at the University of Liège (ULiège) and a member of the study team, Sebastián Zúñiga-Fernándes, stated, “Our analysis shows a unique planetary arrangement: two planets are transiting one star, and the third is transiting its companion star. This makes TOI-2267 the first binary system known to host transiting planets around both of its stars.”

(AI-generated image: Gemini)

According to current planetary formation models, this proximity creates gravitational instability, which should lead to an environment that is unsuited for planet formation. In the case of TOI-2267, however, planets have formed.

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“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,” read a statement from Francisco J Pozuelos, a researcher at the Instituto de Astrofísica de Andalucía (IAA-CSIC) and a partner of the study team.

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Pozuelos and his team received their initial indications regarding these three remote Earth-like planets when they analysed TESS (Transiting Exoplanet Survey Satellite) data with their detection tool, SHERLOCK. This initial sign of planets in the TOI-2267 system led the team to prepare for additional observations with various other observatories.

This encompassed SPECULOOS, a collection of robotic telescopes featuring the SPECULOOS Southern Observatory at the Paranal Observatory in Chile and the SPECULOOS Northern Observatory at the Teide Observatory in Spain’s Tenerife, along with two telescopes in Belgium known as TRAPPIST (Transiting Planets and Planetesimals Small Telescope).

SPECULOOS stands for the Search for habitable Planets EClipsing ULtra-cOOl Stars.

These facilities are uniquely designed to study small exoplanets orbiting cool and dim stars, making them essential for the team to analyse TOI-2267 and reveal its unexpected characteristics.

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Deeper insight into potential planetary arrangements

“This system serves as an authentic natural laboratory for comprehending how rocky planets can form and endure in severe dynamic environments, where we previously believed their stability would be jeopardised,” Pozuelos stated.

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The questions posed about planet formation from this system might be a study that perfectly suits the James Webb Space Telescope and the upcoming generation of terrestrial observatories. These tools are expected to enable astronomers to accurately determine the masses, densities, and potentially the atmospheric composition of the newly identified planets in the TOI-2267 system. The team’s findings were released on Friday, October 24, in the journal Astronomy & Astrophysics.

“Finding three Earth-sized worlds within such a close binary system presents a rare opportunity,” Zúñiga-Fernández stated, adding, “It enables us to examine the boundaries of planet formation theories in intricate settings and to gain a deeper insight into the variety of potential planetary arrangements in our galaxy.”