Tuesday, September 19, 2023

A DIFFERENT KIND OF VLT
Very Large Telescope surprisingly finds exoplanet lurking in 3-body star system

Tereza Pultarova
SPACE.COM
Mon, September 18, 2023 

An artist's illustration of the gas giant discovered in star system HIP 81208. It looks like a cream-colored orb in the foreground. A bright star is seen glowing in the background.

The Very Large Telescope in Chile has photographed a planet orbiting a star in a multi-star system located some 480 light-years from Earth.

The exoplanet, 15 times more massive than our solar system's largest planet Jupiter, orbits a small star that itself orbits a larger star. Also orbiting the larger star is a brown dwarf, or "failed" star. Brown dwarfs are given such a gloomy moniker because these objects are not massive enough to sustain nuclear fusion in their cores like typical stars do, but are still too large to be called planets.

The system of the two stars and the brown dwarf, collectively called HIP 81208, has been known to astronomers for a long time. But the existence of an exoplanet in orbit of the smaller star came as a surprise to astronomers who recently re-examined images of the system taken earlier by the European Southern Observatory's (ESO) Very Large Telescope in Chile.

The newly discovered exoplanet is also quite massive, nearly large enough to be called a brown dwarf itself.

Related: The 10 most Earth-like exoplanets

The team's discovery marks the first hierarchical quadruple system to be found using direct imaging, ESO said in a statement. Most exoplanets are discovered through the so-called transit method, which involves observing subtle dips in a star's brightness caused by a planet passing in front of its disk from the point of the observer.


A diagram showing the quadruple-body star system.

Astronomers thought HIP 81208 was a system consisting of a massive central star (A, the central bright spot), a brown dwarf (B) circling around it, and a low-mass star (C) orbiting further away. However, a new study has revealed a never-before-seen hidden gem: an object (Cb), approximately 15 times more massive than Jupiter, orbiting around the smaller of the two stars (C). (Image credit: ESO/A. Chomez et al.)

Direct imaging is, in essence, traditional photography. However, astronomers using this method to capture deep space worlds use very powerful telescopes and super-sensitive cameras to see planetary subjects directly. And in the reanalyzed images, astronomers from the Paris Observatory detected the giant exoplanet creating a blob in the ring of light surrounding its parent star.

The discovery will help astronomers further their understanding of the formation of complex systems, ESO said in the statement.

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