An international research team including Keele’s Dr John Southworth has captured the first ever image of a young, Sun-like star accompanied by two giant exoplanets. 

Using the European Southern Observatory’s Very Large Telescope (ESO’s VLT), the researchers have taken the first direct image of a planetary system around a star similar to our Sun, located about 300 light-years away and known as TYC 8998-760-1. 

Direct images of exoplanets are notoriously difficult because they are close to but also millions of times fainter than their host stars. Images of systems with multiple exoplanets are thus extremely rare, and — until now — astronomers had never directly imaged more than one planet orbiting a star similar to the Sun. The observations can help astronomers understand how planets formed and evolved around our own Sun. 

Dr Southworth said: “This is hugely exciting because we still do not know whether our own planetary system is an unusual occurrence, or just one of many similar planetary systems around Sun-like stars. Although this new planetary system does not look much like our own – with two giant planets that are much more distant from a much younger star – it is clear evidence that multiple giant planets can form at large distance from stars like our Sun.” 

The research, published in The Astrophysical Journal Letters, was led by Alexander Bohn, a PhD student at Leiden University in the Netherlands. 

Mr Bohn said: “This discovery is a snapshot of an environment that is very similar to our Solar system, but at a much earlier stage of its evolution. 

Co-author Matthew Kenworthy, Associate Professor at Leiden University, said: “Even though astronomers have indirectly detected thousands of planets in our galaxy, only a tiny fraction of these exoplanets have been directly imaged. Direct observations are important in the search for environments that can support life.” 

The direct imaging of two or more exoplanets around the same star is even more rare; only two such systems have been directly observed so far, both around stars markedly different from our Sun. The new ESO’s VLT image is the first direct image of more than one exoplanet around a Sun-like star. ESO’s VLT was also the first telescope to directly image an exoplanet, back in 2004, when it captured a speck of light around a brown dwarf, a type of ‘failed’ star. 

The two gas giants observed in this case orbit their host star at distances of 160 and about 320 times the Earth-Sun distance. This places these planets much further away from their star than Jupiter or Saturn, also two gas giants, are from our Sun; they lie at only five and 10 times the Earth-Sun distance, respectively. The team also found the two exoplanets are much heavier than the ones in our Solar System, with the inner planet having 14 times Jupiter’s mass and the outer one six times. 

Further observations of this system, including with the future ESO Extremely Large Telescope (ELT), will enable astronomers to test whether these planets formed at their current location distant from the star or migrated from elsewhere. ESO’s ELT will also help investigate the interaction between two young planets in the same system. 

Picture credit: ESO/Bohn et al.