EIU Astro

Astronomers find a “Super Earth” with Atmosphere & Water December 17, 2009

The discovery is to be published today (December 17th) in the Journal Nature. A Super-Earth is a rocky planet between one and ten times the mass of the Earth. The planet was discovered orbiting the star, GJ1214, which is a nearby red dwarf about 40 light years from Earth. This type M star is about 1/5 the size of the Sun. The star is cool at 4,900 degrees F (3000 degrees K) compared to the Sun’s 10,000F (5700 degrees K) and has a luminosity only .003 as bright as the Sun.The planet, GJ1214b, is about 6.5 times as massive as the Earth.

Credit: CNN

The MEarth project spotted the planet using a 16″ telescope, The same size as at Eastern Observatory. However , it is not as simple as looking at a random star to see a planet.

The MEarth (pronounced “mirth”) Project is an array of eight identical 16-inch-diameter RC Optical Systems telescopes that monitor a pre-selected list of 2,000 red dwarf stars. Each telescope perches on a highly accurate Software Bisque Paramount and funnels light to an Apogee U42 charge-coupled device (CCD) chip, which many amateurs also use. The project looks for the signature dimming of a star caused by an orbiting planet  eclipsing the star.

Credit: Dan Brocious, CfA

GJ1214b orbits its star once every 38 hours at a distance of only two million kilometres — 70 times closer to its star than the Earth is to the Sun. “Being so close to its host star, the planet must have a surface temperature of about 200 degrees Celsius, too hot for water to be liquid,” said Charbonneau.

However, computer models show that because of its larger diameter, compared to its mass, it may have an interior made of water ice. Because the planet is nearby, the Hubble space telescope has a good chance of directly observing the atmosphere of the planet and measure its composition.