New Zealand researchers have found evidence of a "super-Earth," a chilly Neptune-sized planet.
Using a variant of a technique proposed by Einstein, researchers from Auckland and Massey universities and Auckland's Stardome Observatory, have found signs of a new, icy planet, like a "large, chilly version" of Earth but too cold for life.
"The new planet is Neptune-sized and icy, but unlikely to be covered with a layer of gas like Neptune," Dr Philip Yock of the University of Auckland said.
"Instead it may be more akin to a large, chilly version of our own Earth. The researchers were able to deduce this because they showed that the new planet has no Jupiter-like companion."
Until now there have been no discoveries of Earth-sized terrestrial planets, although more than 100 gaseous Jupiter-sized planets and four medium Neptune-sized planets have been discovered in the past decade.
Yock said the latest find brings the goal of locating an Earth-like planet in the Milky Way a step closer.
The astronomers used the gravitational fields of stars as huge, naturally occurring lenses, as originally proposed by Einstein, a technique that is called "gravitational microlensing".
Competition between the various groups involved in the hunt for an Earth-twin is fierce.
In 2002, Yock, Dr Ian Bond of Massey University and Dr Nicholas Rattenbury of Manchester University published a variant of Einstein's microlensing method by which they thought Earth-sized planets might be found.
At the time, all were working at The University of Auckland.
The three researchers used their method based on data from the Japan/NZ microlensing group called MOA, based at Mt John.
Yock said he, Bond and Rattenbury had submitted a paper reporting the discovery of the new planet to The Astrophysical Journal.
The paper has as co-authors several pioneers of gravitational microlensing who belong to Polish and US-based microlensing groups known as OGLE and MicroFUN.
The gravitational lens that was used to locate the new planet was found by the OGLE group.
Dr Yock believed many more planets would be found with the technique.
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