British astronomers have discovered a rare planetary system in which two planets orbit not one, but two stars at once, like the planet Tatooine from Star Wars. According to scientists, this is only the second such system known to science, according to the article, published in the journal Nature Astronomy.
In 2020, astronomers reported the discovery of exoplanet TOI-1338b orbiting not a single, as usual, but a TOI-1338 double star. Such objects have gained popularity and interest among the public and scientists thanks to the Star Wars planet Tatooine. TOI-1338b was discovered using the so-called transit method, which detects planets by reducing the brightness of a star as the planet passes through its disk. “The transit method allowed us to measure the size of TOI-1338b, but not the mass, which is a fundamental parameter of the planet,” said Matthew Standing from the University of Birmingham.
The TOI-1338 system consists of two gravitationally bound stars with masses of 1.13 and 0.313 solar masses, orbiting a common center of mass with a period of 14 days. A team from the University of Birmingham has already observed this system using a different method, Doppler spectroscopy, which finds planets around stars by capturing the star’s minimal oscillations caused by their attraction. Using precision spectrometers mounted on two telescopes in the Atacama Desert in Chile, scientists attempted to detect the stellar oscillations generated by the planet TOI-1338b and thus calculate its mass. Despite repeated attempts and several years of work, this was not possible, but instead scientists discovered stellar oscillations created by another previously unknown planet, which was given the name BEBOP-1c ( Binaries Escorted By Orbiting Planets).
“At this point, only 12 planets with multiple orbits (which orbit binary stars) are known, and this is the second to contain more than one planet,” David Martin, co-author of the discovery, explained. importance of the discovery.
“BEBOP-1c has an orbital period of 215 days and is 65 times heavier than Earth, which is five times lighter than Jupiter,” Standing said. “It was a difficult system to detect, and our observations were interrupted by the covid pandemic when telescopes in Chile were shut down for 6 months as the planet passed a critical point in its orbit. This part of the orbit became visible last year, when we completed the discovery.” Thus, two planets are currently known in the TOI-1338 binary star system, but scientists do not exclude that similar observations may lead to the discovery of others.
Despite the fact that planets are extremely rare in binary and multiple star systems, their existence helps astronomers understand the mechanisms of planet formation in similar systems.
“Planets form in a disc of material surrounding a young star, where it gradually comes together to form a planet,” said Lalita Sairam, co-author of the discovery. – In the case of a double star, this disc surrounds the two stars. As the stars revolve around each other, they act like a giant dawn, disrupting the disk and preventing planet formation except in areas where it is fairly quiet and far from the binary star. Therefore, in binary systems it is easier to indicate the place and conditions of formation of planets than in the case of single stars like our Sun.
Scientists have not yet been able to estimate the size of the second planet found BEBOP-1c, they will try to do this using the method of transits.
