Astronomers using a giant telescope in Chile have discovered a star with two planets sharing the same orbit.
Planet pairs have been theorized before, but this is the first time any evidence has been found, the astronomers involved said.
“Who could imagine two worlds that share the year round and the habitable conditions?,” said Olga Balsalobre-Ruza, a student at the Astrobiology Center in Madrid, Spain, lead author of the paper published this week i Astronomy & Astrophysics. “Our work is the first evidence that this kind of life could exist.”
The star system, known as PDS 70, is located in the southern hemisphere constellation Centaurus and is 400 light-years from the solar system. Its Jupiter-sized planets, PDS 70b and PDS 70c, were already known, but astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) radio telescope discovered another planet in the orbit of PDS 70b.
Pair of Planets
The ALMA images suggest that it is a second planet, but do not provide enough data to say so definitively. It is therefore thought that one of the planets may be in the process of formation. That’s basically what makes the second planet a cloud of debris and dust.
There is something similar in our solar system, but it has never been found around an exoplanet – Trojans.
Trojan asteroids, in our solar system, are about 12,000 small objects orbiting our sun in two clouds, some in front of Jupiter and some behind it.
Often called “Jupiter’s children,” they are thought to be fossils from the formation and evolution of the planets and the solar system.
‘Exotrojans’ are like unicorns
The two planets orbiting PDS 70 together may be the first ever example of a Jupiter-sized planet and the offspring of Troy in another star system—”exotrojans.”
“Exotrojans are like unicorns so far,” said co-author Jorge Lillo-Box, a senior researcher at the Center for Astrobiology. “They are allowed to exist in theory, but no one has ever felt them.”
Upgrades to the ALMA radio telescope array scheduled for 2030 will make finding and confirming “exotrojans” easier, the researchers said.
“We can imagine that a planet can share its orbit with thousands of asteroids, as happened in the case of Jupiter, but I think that planets could share the same orbit,” said Balsalobre-Ruza.
NASA’s Lucy mission
The Trojans in Jupiter’s orbit fall into two main groups – one ahead of Jupiter and the other behind. They orbit at Lagrange points around Jupiter where they are stabilized by the planet’s gravity and the sun in equilibrium.
Launching in 2021, NASA’s Lucy mission is two years into a 12-year mission to fly six Jupiter Trojans, four of which are binary asteroids (two asteroids that orbit each other). It will also fly by an asteroid in the main Asteroid Belt between Mars and Jupiter.
The spaceship Lucy – which will orbit the sun forever after its mission is completed – is on board a time capsule containing messages from the likes of Albert Einstein, Carl Sagan, Martin Luther King Jr. and four members of The Beatles.
Do you wish a clear sky and wide eyes.