Cosmic giant 300 light-years away in Great Bear is 11 times more massive than Jupiter

Poland

One of the most massive exoplanets to be ever discovered sits 300 light-years from Earth in the Great Bear constellation. Astronomers in Poland have found an oversized exoplanet which is more than 11 times the mass of Jupiter.

It is a cold super Jupiter, meaning it is extremely cold and much larger than Jupiter. The exoplanet and its features were detailed in a paper published last month in Astronomy & Astrophysics.

It resides in a multi-planet system which is a little over 300 light-years away from Earth. The host star of the exoplanet is about 20 per cent more massive and twice as large as our Sun. Named HD 118203, it is also older than our star.

The star system also hosts a hot Jupiter, which is twice the size of Earth. It was discovered in 2005 by the Transiting Exoplanet Survey Satellite (or TESS).

The system continued to intrigue astronomers after the hot Jupiter was found there. Researchers say they knew it had to host another planet, and therefore they studied it. 

“Doppler observations, however, indicated that this was not the end of the story, that there might be another planet out there,” Andrzej Niedzielski, an astronomer at Nicolaus Copernicus University in Poland, said in a university release. “Therefore, we immediately included this system in our observational programs.”

Another planet in star system

They used TESS data and measurements from Telescopio Nazionale Galileo and Texas' Hobby-Eberly telescope to study the system and soon realised that there was another planet orbiting the star.

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However, the planet is not visible because of the star's brightness. They concluded it exists based on the radial velocity data that caused the star’s brightness to slightly change over time.

The orbit times of both planets are also extremely different. While the hot Jupiter found in 2005 completed one orbit in six days, the cold super Jupiter takes 14 Earth years for the same.

The newly discovered super Jupiter is not the biggest exoplanet. TrES-4b, about 1,430 light-years away in the constellation Hercules, has that title. It is 230,000 kilometres across compared to Jupiter’s 142,700 km radius. 

Beta Pictoris b, which is about 12 times the mass of Jupiter and 63 light-years away from Earth, is the nearest in size to the newly found exoplanet.