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The largest exoplanet found

220_planet.jpgAn international team of astronomers with the Trans-atlantic Exoplanet Survey announced the discovery of TrES-4, a new extrasolar planet in the constellation of Hercules. An extrasolar planet or exoplanet is planet which orbits another star like sun in our solar system.

The new planet was identified by astronomers when they were looking for transiting planets – that is, planets that pass in front of their home star(that is ,it is found when it passed between the earth and the star, blocking some of the star’s light and causing a slight drop in its brightness.) – using a network of small automated telescopes in Arizona, California, and the Canary Islands.


The photo is a computer-generated simulation of TrES-4, with its host star on the right. The planet’s home star is bigger and hotter than the Sun, and is about ten times larger than the planet.

Georgi Mandushev, Lowell Observatory astronomer and the lead author of the paper announcing the discovery says,”TrES-4 is the largest known exoplanet,”

It is about 70 percent bigger than Jupiter, the Solar System’s largest planet,but less massive, making it a planet of extremely low density. Its mean density is only about the density of balsa wood!

TrES-4 is about 1400 light years away and orbits its host star in three and a half days. Being only about 4.5 million miles from its home star, the planet is also very hot, about 2,300 degrees Fahrenheit.

The host star of TrES-4 appears to be about the same age as our Sun, but because it is more massive, it has evolved much faster. It has become what astronomers call a ‘subgiant’, or a star that has exhausted all of its hydrogen fuel in the core and is on its way of becoming a ‘red giant’, a huge, cool red star.

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