Astronomers discover EPIC planet with Neptune and Earth similarities

17 May 2016

Artist's impression of an exoplanet. Image via ESO/L. Calçada

A team of astronomers looking into the vast cosmos has located a planet that is the size of Neptune but has a density similar to Earth, and it just happens to be called EPIC212521166 b.

The Neptune-like planet was spotted by NASA’s Kepler spacecraft with help from the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph at the European Southern Observatory’s (ESO) La Silla observatory in Chile, in what has proven to be an important discovery for astronomy.

The team, led by Hugh Osborn of the University of Warwick, has detailed its findings in a research paper, which reveals that EPIC212521166 b is the biggest planet with a sub-Neptune radius found to date.

To find the planet, the team used radial velocity observations surrounding the planet’s nearest star, EPIC212521166 (‘b’ being the added designation for the new planet), which is a metal-poor dwarf star approximately 8bn years old with a mass of slightly more than 0.7 solar masses, located some 380 light years away.

Further analysis of the planet revealed that this new Neptune-like planet orbits its parent star every 14 days, but has a mass 18.3-times greater than our own planet and a radius of around 2.6-times that of Earth.

Could contain water

Given its incredible density, the new planet is likely to have a large rocky core, but the team also argues that the planet could have a hydrogen-helium rich atmosphere and a significant amount of water.

As for what resulted in such a high density, the researchers suggest that mass-radius relations should be used with extreme caution in the regime between terrestrial planets and gas giants.

As for the planet’s lack of a significant hydrogen atmosphere, the team has agreed that this is likely the result of enormous impacts and planet-forming between a former compact multiplanet system.

The team is now continuing its search in the system for any similar exoplanets, but for now, there have been no positive signals detected by the Kepler spacecraft.

Colm Gorey was a senior journalist with Silicon Republic