2023-06-13 11:00:07
Two stars have been observed with two planets orbiting them. This astonishing and rare discovery is the result of the work of an international team of astronomers led by the University of Birmingham.
Artist’s impression of a planet (A planet is a celestial body orbiting around the Sun or another star of…) orbiting around two stars – NASA image
In circumbinary systems, planets orbit two stars rather than just one. The newly discovered planet is called BEBOP-1c, from the name of the project that collected the data, BEBOP for “Binaries Escorted By Orbiting Planets”. The BEBOP-1 system is also known as TOI-1338. In 2020, another circumbinary planet, TOI-1338b, was discovered in the same system using data from NASA’s TESS space telescope. This planet was located thanks to the transit method, which makes it possible to detect a planet when it passes in front of its star (A star is a celestial object emitting light independently, similar to a…) and decreases luminosity slightly (Luminosity designates the characteristic of what emits or reflects…).
However, as explained by Dr. Matthew Standing, who led this research, the method of transits makes it possible to measure the size of a planet, but not its mass, which is nevertheless a fundamental characteristic (In music, the word fundamental can refer to several meanings). For this reason, the BEBOP team used another method, called Doppler or radial velocities, which makes it possible to measure the speed (We distinguish:) of stars.
Despite their best efforts and years of work, the researchers failed to measure the mass of TOI-1338b. But, suddenly, they discovered a second planet, BEBOP-1c, and managed to measure its mass.
Only twelve circumbinary systems are known to date, and it’s only the second that has more than one planet, points out David Martin, an astronomer at the University (A university is an institution of higher education whose objective is the …) of Ohio State. The planet BEBOP-1c has an orbital period (In astronomy, the orbital period designates the duration taken by a celestial body (star, etc.) of 215 days and a mass 65 times greater than that of the Earth, i.e. approximately five times less than that of Jupiter.
According to Dr Lalitha Sairam, a researcher at the University of Birmingham (The University of Birmingham (University of Birmingham or Birmingham University) is the most …), although rare, the circumbinary planets are important for understanding what is happening when a planet is created. Planets are born in a disc of matter surrounding a young star, where mass gradually gathers into planets.
In the case of circumbinary systems, the disk surrounds the two stars. As the latter orbit each other, they act like a large paddle that disrupts the nearby disk and prevents planet formation. Only calm and distant regions of the binary system can generate planets.
For now, only two planets are known in the TOI-1338/BEBOP-1 circumbinary system, but others may be identified in the future.
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