Rocky exoplanet found is gold mine for astronomers

Planet HD 219134b is much closer to Earth – only 21 light-years away.

The closest known exoplanet, the composition of which remains unknown, is almost 15 light-years away.

HD 219134b is transiting, NASA speak for crossing in front of its star, which makes it flawless for scientists to study.

The planet’s distance from Earth sounds quite far, but not relative to other Super Earths.

While HD 219134b is the closest known rocky planet to Earth, it is not the closest planet discovered outside the solar system. Planets like this, referred to as super-Earths, are ubiquitous throughout the galaxy, but we still don’t know a lot about them. “This one is practically a next-door neighbor”, said Lars A. Buchhave, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

While Kepler-452b is larger than Earth, its 385-day orbit is only 5 percent longer. The planet will be an ideal candidate for study by the James Webb Space Telescope set to launch in 2018.

The planet, initially discovered using HARPS-North instrument on the Italian 3.6-meter Galileo National Telescope in the Canary Islands, is the subject of a study accepted for publication in the journal Astronomy & Astrophysics. The CfA is a major partner with the Geneva Observatory on the HARPS-North Collaboration, which includes several other European partners. The planet is 1.6 times the size of Earth, and whips around its star in just three days. In April of this year they targeted the system with NASA’s Spitzer Space Telescope. These planets, Batalha said, are also orbiting around a yellow star like our sun in the orbital “habitable zone” that allows for water to be on the planets’ surface. “Michael Gillon of the University of Liege in Belgium, who led the Spitzer observations of the planet, states that HD 219134b “…can be considered a kind of Rosetta Stone for the study of super-Earths”. Together the mass and the size determine the planet’s density. This shows that HD 219134b is a rocky world.

Its host star is visible to the unaided eye from dark skies, meaning anyone with a good star map can see this record-breaking system. It actually has multiple planets, none of which are habitable. The J2000 equatorial coordinates of HD 219134 are α=23h 13.4m, δ=+57°10′.

It was discovered using the radial velocity technique. The process consists of the planet’s orbit situated between its star and Earth, dimming the star’s light as a result.

But that planet is 1,400 light-years away.

But HD219134b is exciting for another reason: it is the closest transiting planet known to scientists.

ABOVE VIDEO: The closest rocky exoplanet confirmed outside our solar system is located just off the “W” pattern of the Cassiopeia constellation.