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School of Physical and Chemical Sciences

A new Tatooine-like multi-planetary system identified

Researchers in QMUL’s Astronomy Unit were involved in the discovery of a new multi-planetary system orbiting two stars, only the second such system known to exist


An international team of astronomers has announced the second-ever discovery of a multiplanetary circumbinary system. The team involves researchers from Europe and the USA, and includes Prof Richard Nelson and Dr Gavin Coleman, members of QMUL’s Astronomy Unit. The discovery is reported in today’s issue of the journal Nature Astronomy.
Circumbinary systems contain planets that orbit around two stars in the center instead of just one, like in our Solar System. Circumbinary planets orbit around both stars at once. The newly discovered planet is called BEBOP-1c, after the name of the project that collected the data. BEBOP stands for Binaries Escorted By Orbiting Planets. The BEBOP-1 system is also known as TOI-1338.  
In 2020, a circumbinary planet, called TOI-1338b, was discovered in the same system using data from NASA’s TESS space telescope, to which the team also contributed. That planet was discovered with the transit method and was noticed because it passed in front of the brighter of the two stars on several occasions.  
The BEBOP team was already monitoring this system using another detection method at the time, called the Doppler method. This method, also called the wobble method, or radial-velocity method, relies on accurately measuring the velocity of stars.  Using state-of-the-art instruments installed on two telescopes located in the Atacama Desert in Chile, the team attempted to measure the mass of the planet noticed by TESS, but instead they discovered the second planet, BEBOP-1c.

Although rare, circumbinary planets are important in understanding how planetary systems are created. This is where QMUL’s researchers played a key role. Prof Nelson said, “The discovery of circumbinary planets provides a unique opportunity to test our models of planetary formation because the central binary star strongly influences the way in which planets can form and evolve.” Dr Coleman said, “The fact that we were able to develop models to explain this pair of circumbinary planets suggests that we have a reasonably good basic understanding of how planetary systems in a wide range of environments.”
At the moment only two planets are known in the TOI-1338/BEBOP-1 circumbinary system but more might be identified in the future, with similar observations as performed by the team.



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