New image reveals a Jupiter-like world that may share its orbit with a ‘twin’

Researchers using the Atacama Large Millimeter/submillimeter Array of telescopes (ALMA) in Chile may have found a rare “sibling” that shares the same orbit of a Jupiter-like planet some 370 light-years away from Earth in the constellation of Centaur. The newly discovered twin shares the same orbit as PDS 70b around a young star in the PDS 70 system.

[Related: How engineers saved NASA’s new asteroid probe when it malfunctioned in space.]

While two Jupiter-like planets, PDS 70b and PDS 70c, are already known to orbit this star, the team detected a cloud of debris within PDS 70b’s orbital path following this planet’s orbit. The debris could be the start of a new planet, or even the remains of one that has already formed. The findings were published July 19 in the journal Astronomy and Astrophysics. If confirmed, this discovery would present the strongest known evidence that two exoplanets can share an orbit.

“Two decades ago it was theoretically predicted that pairs of planets of similar mass could share the same orbit around their star, the so-called Trojan or co-orbital planets. For the first time, we have found evidence in favor of that idea,” Olga Balsalobre-Ruza, a co-author of the study and a student at the Center for Astrobiology in Madrid, Spain, said in a statement.

Rocky bodies that are in the same orbit as a planet called a Trojan are common throughout our solar system. The more than 12,000 known Jupiterian Trojan asteroids that are in the same orbit as our sun are the most common example. Jupiter-orbiting asteroids were named after the heroes of the Trojan War when they were first discovered, which is why the generic name Trojans is used to describe these celestial objects.

Astronomers have speculated that systems like this could exist around a star other than our sun, appropriately called exotrojans.

“Until now, exotrojans have been like unicorns: they are allowed to exist in theory, but no one has ever detected them,” study co-author and researcher at the Jorge Lillo-Box Center for Astrobiology said in a statement.

In this new study, an international team of scientists analyzed archival ALMA observations of the PDS 70 system and detected the debris cloud at the location of PDS 70b’s orbit where Trojans are expected to exist. Trojans typically occupy two extended regions in a planet’s orbit where the combined gravitational pull of the star and planet can trap material called Lagrangian zones/points. Studying these two regions of PDS 70b’s orbit, the team noted a faint signal coming from one of them, indicating that a debris cloud that has a mass roughly twice that of our moon might be present.

[Related: The James Webb Space Telescope just identified its first exoplanet.]

This cloud of debris could point to an existing Trojan world in this system, or to a planet in the process of forming, according to the team.

“Who could imagine two worlds that share the length of the year and the conditions of habitability? Our work is the first evidence that this type of world could exist,” said Balsalobre-Ruza. “We can imagine that a planet can share its orbit with thousands of asteroids as in the case of Jupiter, but I am surprised that planets can share the same orbit.”

Patience will be key to fully confirm this detection. The team will have to wait until after 2026, when they plan to use ALMA, to see if both PDS 70b and its sister debris cloud move significantly along in their orbit around the star.

“The future of this topic is very exciting and we look forward to the extended capabilities of ALMA, planned for 2030, which will dramatically improve the ability of the array to characterize Trojans on many other stars,” said study co-author and director of the European Observatory. Southern. Itziar De Gregorio-Monsalvo Science Office concluded in a statement.

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