The astronomers discover BEBOP-1c. BEBOP-1c is a second planet discovered by astronomers at the University of Birmingham in the uncommon multi-planetary circumbinary system BEBOP-1 or TOI-1338.
This discovery, made using the Doppler method, is critical in broadening our understanding of the formation of planets around two stars.
Circumbinary systems have planets that orbit two stars in the center rather than simply one, as in our Solar System. Circumbinary planets orbit both stars at the same time.
The discovery, conducted by academics at the University of Birmingham, was published in the journal Nature Astronomy today.
BEBOP-1c is the name given to the newly discovered planet after the name of the project that collected the data. BEBOP is an acronym that stands for Binaries Escorted By Orbiting Planets. TOI-1338 is another name for the BEBOP-1 system.
In the same system, a circumbinary planet known as TOI-1338b was identified in 2020 using data from NASA's TESS space telescope, to which the Birmingham team also contributed.
The transit method was used to discover that planet, which was noticed because it passed in front of the brighter of the two stars on multiple occasions.
Lead author Dr. Matthew Standing earned his Ph.D. at the University of Birmingham and currently works at The Open University stated:
“„The transit method permitted us to measure the size of TOI-1338b, but not its mass which is the planet’s most fundamental parameter.- Dr. Matthew Standing
The BEBOP team was already monitoring this system at the time using another detection method known as the Doppler approach. This method, also known as the wobble method or the radial-velocity method, is based on precisely measuring the movement of stars.
"This is the same method that led to the first exoplanet detection, for which Mayor and Queloz received the Nobel Prize in 2019," noted Matthew's then-supervisor, Amaury Triaud, a professor at the University of Birmingham.
Illustration celebrating the discovery of the circumbinary planet BEBOP-1c using the radial-velocity method. Astronomers rarely put their eye to the telescope, but instead the data comes directly to their computers and laptops where it is analyzed and interpreted. BEBOP-1c was detected using the ESPRESSO instrument at the Very Large Telescope in Chile, and by HARPS, at the 3.6m telescope also in Chile. Both are operated by ESO, the European Southern Observatory The scientists attempted to measure the mass of the planet discovered by TESS using cutting-edge sensors deployed on two telescopes in Chile's Atacama Desert. Despite their best efforts and years of work, the team was unable to achieve this goal, but instead discovered and measured the mass of a second planet, BEBOP-1c.
David Martin, an astronomer and Sagan Fellow at Ohio State University said:
“„Only 12 circumbinary systems are known so far, and this is only the second that hosts more than one planet.- David Martin
“BEBOP-1c has an orbital period of 215 days, and a mass 65 times larger than Earth, which is about five times less than Jupiter’s mass,” continues Dr. Standing. “This was a difficult system to confirm, and our observations were interrupted by the COVID pandemic when telescopes in Chile closed for six months during a critical part of the planet’s orbit. This part of the orbit only became observable again last year, when we finalized the detection.”
Currently, only two planets are known in the TOI-1338/BEBOP-1 circumbinary system, but more could be discovered in the future using similar findings to those made by the researchers.
Although circumbinary planets are uncommon, they are significant in furthering our understanding of what happens when a planet is formed.
Dr. Lalitha Sairam, a researcher at the University of Birmingham and the second author of the study explained:
“„Planets are born in a disc of matter surrounding a young star, where mass progressively gathers into planets. In the case of circumbinary geometries, the disc surrounds both stars. As both stars orbit one another, they act like a giant paddle that disturbs the disc close to them and prevents planet formation except for in regions that are quiet and far away from the binary. It is easier to pinpoint the location and conditions of planet formation in circumbinary systems compared to single stars like the Sun.- Dr. Lalitha Sairam
The team does not yet know the size of BEBOP-1c, only its mass; nevertheless, researchers will attempt to measure the size of BEBOP-1c using the transit method today.
Despite the fact that the inner planet, TOI-1338b, was not detected, the team was able to establish strong upper limits on its mass.
It is currently known that the planet has a density lower than that of a Victoria Sponge cake, a peculiarity that makes this planet ideal for further research with the James Webb space telescope. If these results be confirmed, they may shed light on the chemical environment in which this unusual circumbinary planet evolved.