2009
Planet COROT-7b, with a mass estimated at 4.8 Earth masses and an orbital period of only 0.853 days, was announced on 3 February 2009. The density estimate obtained for COROT-7b points to a composition including rocky silicate minerals, similar to the four inner planets of Earth's solar system, a new and significant discovery. COROT-7b, discovered right after HD 7924 b, is the first super-Earth discovered that orbits a main sequence star that is G class or larger.
The discovery of Gliese 581 e with a minimum mass of 1.9 Earth masses was announced on April 21, 2009. It is the smallest extrasolar planet discovered around a normal star and the closest in mass to Earth. Being at an orbital distance of just 0.03 AU and orbiting its star in just 3.15 days, it is not in the habitable zone, and may have 100 times more tidal heating than Jupiter’s volcanic satellite Io.
Additionally, Gliese 581 d, at 0.2 AU with a 67-day orbital period, has been confirmed to be within the habitable zone of the red dwarf star, making it the first exoplanet where the existence of liquid water is a real possibility.
A planet found in December 2009, GJ 1214 b, is 2.7 times as large as Earth and orbits a star much smaller and less luminous than our Sun. "This planet probably does have liquid water," said David Charbonneau, a Harvard professor of astronomy and lead author of an article on the discovery. However, interior models of this planet suggest that under most conditions it does not have liquid water.
By November 2009, a total of 30 super-Earths had been discovered, 24 of which were first observed by HARPS.
Read more about this topic: Super-Earths, Discoveries, More Notable Super-Earth Discoveries By Year