The planet hangs around a red dwarf

Jan 21, 2009 11:30 GMT  ·  By

A new world was recently discovered by astronomers at the Harvard-Smithsonian Center for Astrophysics, orbiting a red dwarf just 120 light-years away from Earth. The planet, which is a bit larger than Neptune, has been dubbed HAT-P-11b, and preliminary calculations show that the new body has a mass roughly equivalent to 25 times that of our own planet. By comparison, Neptune only has 17 times the mass of Earth.

It was only by accident that the new planet was discovered. It transited (passed in front) of the star it orbited, reducing its luminosity index by 0.4 percent. Even if the change was very small, the automated HATNet telescope array, based in Arizona and Hawaii, picked it up, and called on a human operator. The celestial body is now the 11th exoplanet found by the automated system, and also one of the smallest ever discovered with any of the existing telescope arrays in the world to date.

According to the team at HSC, the planet revolves very very close to its star, completing a full rotation in less than 5 days. For reference, Mercury, the closest planet to the Sun in our solar system, completes the same rotation in 88 days. This closeness with its star causes the Super-Neptune planet to be heated at temperatures averaging 1,100 degrees Fahrenheit (roughly 600 degrees Celsius). The size of the newfound is roughly the same as that of three quarters of our Sun.

The HAT-P-11 system may hold another planet, astronomers say, but further readings and, maybe, sheer luck are required in order to determine its location, and other physical and chemical properties. If it orbits its star on a distant orbit, it may take one year, or maybe more before it moves in front of the star again, so that telescopes can pick it up.

"Having two such objects to compare helps astronomers to test theories of planetary structure and formation," Gaspar Bakos, the leader of the Harvard astronomy team, explains.