The fourth is not extra: Astronomers find an exoplanet in a triple system

European astronomers have announced the discovery of an exoplanet that is part of a very unusual triple system, HIP 81208. It consists of a blue giant as well as red and brown dwarfs. 

HIP 81208 star system. Source: ESO/A. Chomez et al.

HIP 81208 is located at a distance of 485 light-years from Earth. This is a very young star system. Its age is estimated at only 17 million years, and it is part of one of the subgroups of the Scorpius–Centaurus star association.

The main component of the system is a star of spectral class B (in the picture, it is indicated by the letter A). Until recently, astronomers were aware of two objects orbiting it — a brown and a red dwarf (they are designated by the letters B and C). The orbit of the brown dwarf passes at a distance of 54 AU from the central star, its mass exceeds the mass of Jupiter by 67 times. The orbit of the red dwarf passes further, at a distance of 234 AU from the center of the system.

But now it is known that HIP 81208 is home to at least one more object. It was discovered by direct observation. It was found in an image taken using a SPHERE receiver mounted on a Very Large Telescope. In the presented photo, this object is indicated by the letters Cb.

The found body orbits a red dwarf. According to the researchers, its mass exceeds the mass of Jupiter by about 15 times. So it’s either a brown dwarf or a very massive gas giant. According to the researchers, they intend to continue observing this very unusual system to more accurately determine the characteristics of the objects included in it, as well as to search for other bodies that have so far escaped their gaze.

According to https://www.eso.org

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