The REAL Star Wars Planet! Scientists discover a new world in a Tatooine-like system
In a galaxy far, far away, Luke Skywalker lived on a rocky planet called Tatooine that revolved around two stars at once, giving the hero a “double sunset.”
Now astronomers have discovered a real planet, called TOI-1338 c, orbiting its own set of stars.
TOI-1338 c is a gas giant that has about 65 times the mass of Earth and takes 215 days to orbit the sun, the experts reveal.
It is the second planet in this distant solar system, following the discovery of TOI-1338 b in 2019.
Both orbit their star in the solar system, called TOI-1338, which is about 4.4 billion years old and located 1,300 light-years away from Earth, in the constellation Pictoris.
Some exoplanets orbit two stars at once, like the planet Tatooine in the 1977 movie “Star Wars” (pictured)
An artist’s impression of such a system where one star is brighter than the other. At the turn of the century, the existence of orbiting planets was still “restricted to science fiction,” but this changed in 2011 when the discovery of the first-ever orbiting planet, Kepler-16b, was announced.
An international team including experts from the universities of Birmingham, London, St. Andrews and Keele has described the findings in a study.
“We report the detection of a gas giant planet orbiting both stars of an eclipsing binary star system,” they say in their paper, published today in Nature Astronomy.
“The system discussed in this article is only the second system known to host multiple planets.”
Both TOI-1338 b and TOI-1338 c are “circumbinary planets” — planets that orbit two stars instead of one.
As late as the turn of the century, the existence of circumferential planets was still “restricted to science fiction,” say the authors.
But all this changed in 2011 when the discovery of the first-ever circumbinary planet, Kepler-16b, was announced.
This newly discovered planet, TOI-1338 c, is a gas giant, while TOI-1338 b is a “Neptune-like ice giant, according to NASA.
TOI-1338 c is further away from its star and in a wider orbit than TOI-1338 b, which was discovered by a NASA intern in the summer of 2019 using the popular transit method.
TOI-1338 b, discovered in 2020, is closer to its star than TOI-1338 c, the newly discovered planet
The transit method is based on detecting periodic dips in starlight, which indicate that a planet is crossing and briefly blocking the light from its star.
However, circumbinary planets are difficult to find in the data because the stars can obscure each other, making planetary transits difficult to discern.
Using state-of-the-art instruments installed on two telescopes in Chile’s Atacama Desert, the study’s authors attempted to measure the mass of this first planet.
Although they failed, their efforts were rewarded with the discovery of TOI-1338 c.
‘[TOI-1338 c] has an orbital period of 215 days and a mass 65 times greater than Earth’s, which is about five times less than the mass of Jupiter,” said first author Dr. Matthew Standing, who is now a researcher at The Open University.
Instead of the transit method, the experts used radial velocity, also known as the wobble or Doppler method, which can detect “wobbles” in a star caused by the gravity of a planet orbiting Earth.
This discovery, the team says, is the first time astronomers have found an orbiting planet using radial velocity.
While only two planets are known in the TOI-1338 system, more may be identified in the future through similar observations as conducted by the team.
Twelve circumbinary star systems are known to date, but this is only the second to host more than one planet, after Kepler-47, making a total of 14.
Researchers used the ESPRESSO spectrograph at the Very Large telescope facility in northern Chile’s remote, sparsely populated Atacama Desert (pictured)
Kepler-47’s three known planets — b, d, and c — have orbital periods of 49.5, 187.4, and 303.2 days, respectively. Its orbit places it within the “habitable zone” – the proper distance for liquid water to exist on its surface.
Planets orbiting two stars suffer from the gravitational pull of two separate stars and thus run the risk of being ejected into space.
But the existence of orbiting planets also raises the question of how they formed in the first place.
“Planets are born in a disk of matter around a young star, where mass gradually accumulates into planets,” said author Dr Lalitha Sairam of the University of Birmingham.
‘In the case of circumbinary geometries, the disk surrounds both stars.
“As both stars orbit each other, they act like a giant paddle, distorting the disk close to them and preventing planet formation, except in regions that are quiet and far away from the binary.”