Astronomers made a groundbreaking discovery as they spotted two exoplanets that may be sharing the same orbit. This is the first time such behavior has been observed in planets. Additionally, they were able to capture the first-ever photo of this phenomenon.
Using the Atacama Large Millimeter/submillimeter Array (ALMA), the research team investigated the system surrounding the star PDS 70, which is located 400 light-years away from Earth.
This system is known to have two exoplanets, namely PDS 70 b and PDS 70 c. Upon analyzing the archival ALMA observations of the system, the team encountered a cloud of debris in the same location as expected “Trojans” in PDS 70b’s orbit.
Trojans are rocky bodies that share the same orbit as a planet and are quite common in various celestial bodies, including our own Solar System.
The most famous example is the Trojan asteroids existing in Jupiter’s orbit that consists of over 12,000 rocky bodies. Interestingly, Trojan asteroids even exist within Earth’s orbit.
This discovery provides evidence of the potential existence of two planets sharing the same orbit, which has hitherto been similar to the mythical creature, the unicorn.
According to Jorge Lillo-Box, a senior researcher at the Centre for Astrobiology in Madrid, “Exotrojans [Trojan planets outside the Solar System] have so far been like unicorns: they are allowed to exist by theory but no one has ever detected them.”
The research findings, published in the journal Astronomy & Physics, support the theoretical prediction made two decades ago about planets of similar mass sharing the same orbit as Trojan or co-orbital planets.
This groundbreaking observation provides the first evidence of the possibility of this idea being true.
Trojans are typically found in specific regions along a planet’s path where the combined gravitational forces of the planet and its star facilitate the capture of objects like rocks and dust.
Scientists discovered a weak signal indicating a massive debris cloud weighing approximately twice as much as our Moon in one of these regions of PDS 70b’s orbit.
The team suggests that this debris cloud may indicate the presence of either an existing Trojan world or a planet in the process of formation within the system.
Olga Balsalobre-Ruza, the lead author of the paper and a student at the Centre for Astrobiology, expresses astonishment, stating, “Who could imagine two worlds that share the duration of the year and the habitability conditions? Our work is the first evidence that this kind of world could exist.”
Co-author Nuria Huélamo, a senior researcher at the Centre for Astrobiology, emphasizes that their research serves as the initial step in identifying co-orbital planets during their early formation.
Itziar De Gregorio-Monsalvo, ESO Head of the Office for Science in Chile and another contributor to the study, points out that this discovery raises questions about the formation, evolution, and frequency of Trojans in different planetary systems.
The team intends to use ALMA after 2026 to monitor the significant movement of both PDS 70b and the surrounding debris cloud along their orbit around the star.
If observed, this would be a breakthrough in exoplanetary studies. The researchers eagerly anticipate the enhanced ALMA capabilities planned for 2030, which will tremendously improve the array’s ability to study Trojans in multiple star systems.
Intriguingly, planets sharing the same orbit can exist, and astronomers have the evidence. This discovery challenges conventional understanding and opens doors to unimaginable possibilities in photography among the stars.
