Researchers using the Chilean Atacama Large Millimeter/submillimeter Array of telescopes (ALMA) may have found a rare “brother” share the same orbit of a Jupiter-like planet about 370 light-years away from Earth in the constellation Centaurus. The newly discovered twin shares the same orbit as PDS 70b around a young star in the PDS 70 system.
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While two Jupiter-like planets, PDS 70b and PDS 70c, are already known to orbit this star, the team discovered a cloud of debris within the orbit of PDS 70b following the orbit of this planet. The debris could be the start of a new planet, or even the remains of a planet that has already formed. The findings were published July 19 in the magazine Astronomy and astrophysics. If confirmed, this discovery would provide the strongest known evidence that two exoplanets may share one orbit.
“Twenty years 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 found evidence for that idea,” said Olga Balsalobre-Ruza, a study co-author 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 Trojan horses occur throughout our solar system. Jupiter’s more than 12,000 known Trojan asteroids that are in the same orbit as our sun are the most common example. The asteroids in Jupiter’s orbit were named after the heroes of the Trojan War when they were first discoveredtherefore the collective term Trojan horses is used to describe these celestial bodies.
Astronomers have speculated that such systems could exist around a star other than our sun, aptly named Exotrojans.
“Exotrojans have been like unicorns so far: they may exist in theory, but no one has ever discovered them,” wrote co-author and researcher at the Center for Astrobiology Jorge Lillo-Box. said in a statement.
In this new study, an international team of scientists analyzed archived ALMA observations from the PDS 70 system system and discovered the debris cloud at the location in PDS 70b’s orbit where Trojans are expected to exist. Trojan horses typically occupy two vast regions in a planet’s orbit where the combined gravity of the star and planet can trap material that Lagrangian zones/points. By studying these two regions of PDS 70b’s orbit, the team noticed a faint signal emanating from one of them, indicating that a cloud of debris with a mass roughly twice that of ours may be present. Moon.
[Related: The James Webb Space Telescope just identified its first exoplanet.]
According to the team, this cloud of debris could indicate an existing Trojan world in this system, or a planet in the making.
“Who can imagine two worlds sharing the length of the year and the conditions of habitability? Our work is the first proof that this kind of world could exist,” said Balsalobre-Ruza. “We can imagine that a planet could share its orbit with thousands of asteroids, as in the case of Jupiter, but I’m surprised that planets could share the same orbit.”
Patience will be key to fully confirm this detection. The team will have to wait until after 2026when they plan to use ALMA to see if both PDS 70b and its sister debris cloud move significantly along their orbits around the star.
“The future of this topic is very exciting and we look forward to the expanded ALMA capabilities, planned for 2030, which will dramatically improve the array’s ability to characterize Trojans in many other stars,” said study co-author and head of the European Southern Observatory of the Bureau of Science Itziar De Gregorio-Monsalvo concluded in a statement.
