Team Finds Three Super-Earths in a tight formation 21 Light Years away

An international team of researchers discovered a new planetary system about 21 light years away. The system consists in three super-Earths, or (not-necessarily rocky) planets that are larger than the Earth but smaller than our solar system’s icy giants, and a gas giant.

All four space bodies are locked into a tight orbit around their host star, a dwarf star which is slightly smaller and colder than the Sun. The newly detected planetary system which was dubbed HD219134 after its host star is located in the constellation Cassiopeia, researchers reported.

Surprisingly, one of the three super-Earths was qualified as the closest transiting planet ever discovered. On an astronomical scale, the system is relatively “close” enough to allow astronomers take some snapshots of the system and its inhabitants.

The discovery was made with help from HARPS-N, a system mounted on the Telescopio Nazionale Galileo, an Italian ground telescope located in the Canary Islands.

In the northern hemisphere, HD219134 star is visible to the naked eye all year long next to one of the legs of its constellation. The authors of the discovery estimate that the three super-Earths are “mostly” rocky planets, while the forth outer planet is gaseous. This is a structure that is very similar to our solar system – inner planets closer to its core and gaseous giants in its outer reaches.

Ati Motalebi, senior researcher involved in the discovery and astronomy professor at University of Geneva, recalls that his team phoned NASA immediately after the discovery to confirm the findings via its Spitzer space telescope.

Ms. Motalebi, asked NASA to confirm whether one of the super-Earths orbited the host star every three days as initial findings had suggested. She said that a mini-eclipse, or a casual transit of the planet in front of the dwarf star, was enough to confirm the discovery and allow the team to measure the size of the newly-spotted super-Earth.

That planet which was named HD219134b indeed transits its host star and is the closest planet to transit a star astronomer have encountered so far, NASA researchers noted. Astronomers were able to measure the planet’s average density as well and learned that it is 4.5 times heavier than the Earth is, and more than 1.5 times larger.

From its density, scientists concluded that the two planets may be closely related. The other two super-Earths were also measured. One of them is 2.7 times more massive than our planet, while the other is 8.7 times heavier than the Earth.

A study on the findings was recently published in the Astronomy & Astrophysics journal.

Image Source: Smithsonian Science