An international group of astronomers has announced the second discovery of a system around a multiplanetary planet in history. Circular systems have planets orbiting two central stars instead of one, as in our solar system. Round planets orbit both stars at the same time. The discovery, led by researchers from the University of Birmingham, is reported in the journalism. Nature Astronomy.

The newly discovered planet was named BEBOP-1c after the project that collected the data. BEBOP stands for Binary Files Associated with Orbiting Planets. The BEBOP-1 system is also known as TOI-1338. In 2020, a planet named TOI-1338b was discovered in the same system using data from NASA’s TESS space telescope, also involving a team from Birmingham. This planet was discovered by transit and was noticed because it passed in front of the brighter of the two stars several times.

“The transit method allowed us to measure the size of TOI-1338b, but not the planet’s most important parameter, its mass,” said lead author Dr. Matthew Standing, Ph.D. He is a researcher at the University of Birmingham and currently the Open University.

At the time, the BEBOP team was already monitoring this system using another detection method called the Doppler method. This method, also called the “oscillation” method or the radial velocity method, relies on the precise measurement of the velocities of stars.

“This is the same method that led to the first detection of an exoplanet, for which Mayor and Keloz won a Nobel Prize in 2019,” said Amory Trio, a professor at the University of Birmingham, Matthew’s then-supervisor.

Using state-of-the-art instruments mounted on two telescopes in Chile’s Atacama Desert, the team attempted to measure the mass of the planet seen by TESS. Despite their best efforts and years of work, the team failed to do so and instead discovered a second planet, BEBOP-1c, and measured its mass.

“There are currently only 12 extrastellar systems known, and this is only the second system to contain more than one planet,” said David Martin, an astronomer and Sagan research fellow at Ohio State University.

Dr. “BEBOP-1c has an orbital period of 215 days and a mass 65 times the mass of Earth, about five times less than that of Jupiter,” Dr. Standing continues. “This system has been difficult to verify, and our observations were interrupted by the COVID epidemic when telescopes in Chile were shut down for six months in a critical part of the planet’s orbit. This part of the orbit was only observed again last year, when we completed detection.”

Only two planets in the TOI-1338/BEBOP-1 ring system are currently known, but more may be identified in the future with observations like the team’s. Planets around a planet, although rare, play an important role in understanding what happens during planet formation.

The second author of the study and University of Birmingham researcher Dr. Lalita Sairam, “Planets are born in the disk of matter surrounding a young star, where the mass gradually turns into planets.”

“In the case of a circular geometry, the disk surrounds both stars. As the two stars rotate against each other, they act like giant spades that disturb the adjacent disk and prevent planet formation, except in quiet and distant regions. It is easier to determine the location of planets and the conditions of their formation.”

The team does not yet know the size of BEBOP-1c, only its mass, but the researchers will try to use the transit method to measure the size of BEBOP-1c.

While TOI-1338b’s inner planet has not been detected, the team was able to set strict upper limits on its mass. The planet is now known to have a lower density than Victoria Biscuit, making it the most suitable planet for further research with the James Webb Space Telescope. If these observations come true, they could reveal the chemical environment in which this rare earth formed around the planet. Source