Planets like Earth are circling the faint stars in the Milky Way according to the new research
. The estimate for the number of so called "Super-Earths
" are based on detections of the number of red-dwarf stars
in the Galaxy.
Harps employs an indirect method of detection that infers the existence of orbiting planets from the way their gravity makes a parent star appear to twitch in its motion across the sky.
The team's leader Xavier Bonfils from the Observatoire des Sciences de l'Univers de Grenoble, France said:
"Our new observations with Harps mean that about 40% of all red dwarf stars have a super-Earth orbiting in the habitable zone where liquid water can exist on the surface of the planet.
"Because red dwarfs are so common - there are about 160 billion of them in the Milky Way - this leads us to the astonishing result that there are tens of billions of these planets in our galaxy alone."
The team investigated a total of 102 of carefully chosen red dwarfs, which are stars that are dimmer and cooler than our sun.
The team found nine super-earths, which are planets with mass one to ten times the size of Earth, with two of these planets being inside the habitable zone of their stars.
Liquid water is deemed a necessity for life to develop on potentially habitable planets.
"The habitable zone around a red dwarf, where the temperature is suitable for liquid water to exist on the surface, is much closer to the star than the Earth is to the Sun," commented co-researcher Stephane Udry from the Geneva Observatory
"But red dwarfs are known to be subject to stellar eruptions or flares, which may bathe the planet in X-rays or ultraviolet radiation, and which may make life there less likely."