Billions of habitable worlds lurking in Milky Way
Our galaxy may be teeming with billions of habitable planets, which could have huge consequences on the search for extra-terrestrial life, according to a recent survey.india Updated: Apr 30, 2012 17:50 IST
Our galaxy may be teeming with billions of habitable planets, which could have huge consequences on the search for extra-terrestrial life, according to a recent survey.
Two Princeton researchers recently contemplated that we really might be alone in the universe, but the study of red dwarf stars in the Milky Way discovered nine super-Earths - and two in the ‘habitable zone’ where liquid water could exist.
Red dwarf stars account for 80 per cent of the 200 to 400 billion stars in our galaxy and scientists now believe that 40 per cent of those might have a planet in the habitable zone, the Daily Mail reported.
The news that the Milky Way may include billions of habitable planets has given California-based SETI institute - the Search for Extraterrestrial Intelligence scientists something to smile about
“SETI is looking for Mr. Right or maybe Ms. Right, depending on your point of view. It helps to find out that there''s 10 times as many candidates as there were before,” SETI Senior Astronomer Seth Shostak said.
However, Shostak has cautioned that because red dwarfs are comparatively dim, planets would need to orbit very close to them to get enough heat for life to grow, which would mean they’d receive potentially fatal doses of radiation.
Protection may exist, though, in the form of a magnetic field around the planet – or large oceans, which would guard aquatic life.
“We''re not sure intelligent life, if under water, will be building radio transmitters and we''re going to hear from them,’ Shostak said.
“But it’s possible.”
The revelation that the Milky Way may be packed with habitable planets came from an international team of star gazers led by Dr Xavier Bonfils, from Grenoble University in France.
“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,” he said.
The astronomers surveyed a cautiously chosen sample of 102 red dwarfs using the European Southern Observatory’s 3.6-metre telescope at La Silla, Chile.
A total of nine super-Earths - planets with masses between one and 10 times that of Earth - were discovered.
Two were situated within the habitable zones of the stars Gliese 581 and Gliese 667 C.
These data were combined with other observations, including those of stars that did not have planets.
The astronomers worked out that habitable zone super-Earths orbiting red dwarfs occurred with a frequency of nearly 41 per cent.
On the other hand, massive planets, similar to Jupiter and Saturn, were rare around red dwarfs. Less than 12 per cent of the stars were expected to have such ‘gas giants’.
As red dwarfs are common near the sun, many ‘super-Earths’ may not be far away in astronomical terms.
The scientists have estimated that there could be about 100 habitable zone planets within 30 light years.
The research has been published in the journal Astronomy ‘n’ Astrophysics.