A Trio Of Super-Earths

Today, in an international conference, a team of European astronomers announced a remarkable breakthrough in the field of extrasolar planets. With the HARPS instrument on the ESO La Silla observatory, they've found a system of triple super-earth around the star HD 40307th In addition, searches of their total sample and harps, the astronomers are a total of 45 candidates planet with a mass below 30 Earth masses and an orbital period of less than 50 days. This means that a solar-star of three ports such planets.

"Does every single star port planet, and if so, how many?"
Miracle planet hunter Michel Mayor of Geneva Observatory. "We can not yet know the answer, but we make great progress towards."

Since the discovery in 1995 of a planet around the star 51 Pegasi by Mayor and Didier Queloz, more than 270 exoplanets have been found, mostly around solar-like stars. Most of these planets are giants, like Jupiter or Saturn, and current statistics show that about 1 of
Stars 14 ports this kind of planet.

"With the advent of much more precise instruments such as the HARPS spectrograph on the ESO 3.6-m telescope at La Silla, we can now discover smaller planets with masses 2 to 10 times the mass of the earth,"
Says Stephane Udry, the mayor colleagues. Such planets are called super-earth, because they are more massive than the Earth, but less massive than Uranus and Neptune (about 15 Earth masses).

The group of astronomers have now discovered a system of three "super-earth to a more normal star, which is slightly less massive than our sun and located 42 light years away in the direction of the southern constellation Doradus and Pictor.

"We have very precise measurements of the speed of the star HD
40307 in the last five years, which clearly show the presence of three planets, "says Mayor.

The planet, with 4.2, 6.7 and 9.4 times the mass of Earth orbit the star with periods of 4.3, 9.6 and 20.4 days, respectively.

"The interference by the planets are really small - the mass of the smallest planet is a hundred thousand times smaller than the star - and only the high sensitivity of the HARPS made it possible to detect," says co-author Francois Bouchy, from the Institute Astrophysique de Paris, France.

Because each planet induces a movement of the star of only a few meters per second.

At the same conference, the team of astronomers announced the discovery of two other planetary systems, even with the HARPS spectrograph. In one, a super-Earth (7.5 masses) orbiting the star HD 181433 to 9.5 days. This star has a Jupiter-like planet with a period of close to 3 years. The second system includes a 22-mass of the planet earth with a duration of 4 days and a Saturn-like planets with a 3-year period as well.

"Of course these planets are only the tip of the iceberg," says Mayor.
"The analysis of all the stars studied with HARPS shows that around one third of all solar-like stars have either super-Earth or Neptune-like planets with orbital data shorter periods than 50 days."

A planet in a narrow, short-period orbit is in fact easier to find than a in a broad, long-period orbit.

"It is very likely that there are many other planet: not only super-Earth and Neptune-like planets with longer periods, but also Earth-like planets, we can not recognize it yet. Add it to the Jupiter-like Planets already known, and you may well arrive at the conclusion that planets are everywhere, "concludes Udry.