WASHINGTON, Feb 7:
Earth-like planets could be just a stone’s throw from our Milky Way galaxy and may even harbour life more advanced than on Earth, astronomers believe.
Six per cent of red dwarf stars have habitable, Earth-sized planets, astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA), who used publicly available data from NASA’s Kepler space telescope, have found.
Since red dwarfs are the most common stars in our galaxy, the closest Earth-like planet could be just 13 light-years away, researchers said.
“We thought we would have to search vast distances to find an Earth-like planet. Now we realise another Earth is probably in our own backyard, waiting to be spotted,” said Harvard astronomer and lead researcher Courtney Dressing.
Red dwarf stars are smaller, cooler, and fainter than our Sun. An average red dwarf is only one-third as large and one-thousandth as bright as the Sun. From Earth, no red dwarf is visible to the naked eye.
Despite their dimness, these stars are good places to look for Earth-like planets. Red dwarfs make up three out of every four stars in our galaxy for a total of at least 75 billion.
The signal of a transiting planet is larger since the star itself is smaller, so an Earth-sized world blocks more of the star’s disk. And since a planet has to orbit a cool star closer in order to be in the habitable zone, it’s more likely to transit from our point of view.
Dressing culled the Kepler catalogue of 158,000 target stars to identify all the red dwarfs. She then re-analysed those stars to calculate more accurate sizes and temperatures. She found that almost all of those stars were smaller and cooler than previously thought.
Since the size of a transiting planet is determined relative to the star size, based on how much of the star’s disk the planet covers, shrinking the star shrinks the planet. And a cooler star will have a tighter habitable zone.
Dressing identified 95 planetary candidates orbiting red dwarf stars. This implied that at least 60 per cent of such stars have planets smaller than Neptune. However, most weren’t quite the right size or temperature to be considered truly Earth-like.
Three planetary candidates were both warm and approximately Earth-sized. Statistically, this means that six per cent of all red dwarf stars should have an Earth-like planet.
“We now know the rate of occurrence of habitable planets around the most common stars in our galaxy,” said co-author David Charbonneau.
“That rate implies that it will be significantly easier to search for life beyond the solar system than we previously thought,” Charbonneau said in a statement.
Our Sun is surrounded by a swarm of red dwarf stars. About 75 per cent of the closest stars are red dwarfs. Since 6 per cent of those should host habitable planets, the closest Earth-like world is likely to be just 13 light-years away.
The study was published in The Astrophysical Journal. (PTI)

BANGALORE, Feb 7:
Indian Defence Aviation major Hindustan Aeronautics Ltd today said it would foray into production and servicing of Unmanned Aerial vehicle (UAV) and was already in talks with Aeronautical Development Establishment (ADE) for the production of Rustom-2 drone.
Talking to mediapersons here, HAL Chairman R K Tyagi said HAL would be investing Rs 500 crore for manufacture and technology development of UAVs. It would also like to be manufacturing and maintenance hub for UAVs.
He said it had already been in talks with the government in this regard.
Mr T Suvarna Raju Director for design and development said HAL was also in dialogue with premier technology education institutions such as Indian institute of Science and the IIT, Chennai for academic collaboration with them.
It has proposed to the Union Home Ministry that the Navratna company will prepare a blue-print vis-a-vis UAV requirements for para-military forces.
Mr Tyagi said HAL would design and develop a 20 kN aero-engine. ‘It will be a great emerging market to come because in a few years aero-engine market in India is expected to the tune of Rs 2,50,000 crore’.
Mr Raju said Bangalore-headquartered defence PSU has the expertise of manufacturing engines under licence agreements and knows the technology involved.
‘HAL is venturing into creating a mig-segment engine which will be used either on trainers what we have or regional jets (aircraft) we are looking at’, he said.
He said the preliminary design of this engine would be reviewed in September this year and the prototype is planned to be tested in three years.
The HAL is in discussion with the Ministry of Human Resources Development to create an aviation university based in Bangalore which will be ‘full-fledged in every way’, he added. (UNI)

LONDON, Feb 7:
Researchers have identified the world’s largest prime number yet, beating the previous record by over four million digits.
The number has now shot up to 2 multiplied by itself 57,885,161 times minus 1, breaking a four-year dry spell in the search for new, ever-larger primes.
Curtis Cooper from the University of Central Missouri in Warrensburg made the finding as part of the Great Internet Mersenne Prime Search (GIMPS), a distributed computing project designed to hunt for a particular kind of prime number first identified in the 17th century, the ‘New Scientist’ reported.
“It’s sort of like finding a diamond,” says Chris Caldwell at the University of Tennessee, Martin, who keeps a record of the largest known primes.
“For some reason people decide they like diamonds and so they have a value. People like these large primes and so they also have a value,” said Caldwell.
All prime numbers can only be divided by themselves and 1. The rare Mersenne primes all have the form 2 multiplied by itself p times minus 1, where p is itself a prime number.
The new prime, which has over 17 million digits, is only the 48th Mersenne prime ever found and the 14th discovered by GIMPS. The previous record holder, 2 multiplied by itself 43,112,609 times minus 1, which was also found by GIMPS in 2008, has just under 13 million digits.
All the top 10 largest known primes are Mersenne primes discovered by GIMPS. Until today, the most recent addition to the list was found in 2009, but it was smaller than the 2008 discovery.
Though there are an infinite number of primes, there is no formula for generating these numbers, so discovering them requires intensive computation.
GIMPS uses volunteers’ computers to shift through each prime-number candidate in turn, until eventually one lucky user discovers a new prime.
GIMPS software runs on around a thousand university computers, one of which spent 39 days straight proving that the number was prime, which was then independently verified by other researchers. (PTI)