हमारी अपनी नीहारिका (गेलेक्सी मिल्की -वे )में ऐसे ही जीवनक्षम सितारों की भरमार है। इसके अपने ही चार भाई और हैं यह ...

हाथ लगा पृथ्वी का जुड़वाँ संगी 

जिसके पास अपना पर्याप्त गुरुत्व भी है नैजिक वायुमंडल 

को थामे रखने में समर्थ ,सम्भवतया जिसकी ठोस सतह  

पर 

जल और जीवन भी है ऐसा ग्रह सौर मंडल के पार खगोल 

विज्ञानियों ने अपने प्रेक्षण में लिया है। 

अमरीकी अंतरिक्ष अभिकरण (अंतरिक्ष संस्था नासा )ने इसे 

 

केप्लर दूरबीन की मदद से प्रेक्षण में लिया है जिसे नाम 

दिया 

गया है केप्लर -१८६ f.

जीवन क्षम ग्रह आवासीय क्षेत्र में इसे अपने पितृ सितारे की 

परिक्रमा लगाते देखा गया है.

इससे प्राप्त विकिरण की तीव्रता और वर्णक्रम (स्पेक्ट्र्म 

)इशारा करता है ,यह अपने पेरेंट स्टार से इतनी दूरी बनाये 

हुए हैं जहां से जल के तरल रूप में मौजूद बने रहने की 

संभावना बलवती हो जाती है। 

भले इसका पितृ सितारा  सूरज के मुकाबले अपेक्षाकृत 

कमगरम (या ठंडा बौना सितारा ही है )लेकिन हमारी अपनी 

नीहारिका (गेलेक्सी मिल्की -वे )में ऐसे ही जीवनक्षम 

सितारों की भरमार है। इसके अपने ही चार भाई और हैं यह 

पांचवां पूत है अपने पिता का।  

सौर ज्वाला और विकिरण का बाहुल्य लिए रहते हैं यह 

सूरज 

 

से खासा ज्यादा सक्रीय बौने सितारे (हमारा सूरज भी 

औसत 

 

दर्ज़े का एक बौना सितारा है अंतरिक्ष में इससे लाखों लाख 

गुना आकारी भीमकाय सितारे मौजूद हैं ,सूरज की बिसात 

क्या है ,पिद्दी न पिद्दी का सोरबा लेकिन इसके बिना जीवन 

सम्भव ही नहीं हैं ,समन्दरों से पानी उड़ा कर सूरज ही 

वर्षाजल के रूप में लौटाता है तमाम किस्म के  जीवन चक्रों 

को चलाये हुए है गत साढ़े चार अरब बरसों से )पढ़िये 

ताराविज्ञान से ताल्लुक रखने वाली यह अद्यतन रिपोर्ट :

Earth’s twin where life can exist found

LONDON: Earth's twin - a habitable planet with its own atmosphere and solid surface where liquid water and possibly life can exist has been found outside our solar system. 

The new planet, dubbed Kepler-186f, was discovered using Nasa's Kepler telescope launched in March 2009 to search for a habitable zone, earth-sized planets in our corner of the Milky Way galaxy. 

A habitable zone planet orbits its star at a distance where any water on the planet's surface is likely to stay liquid. Since liquid water is critical to life on earth, many astronomers believe the search for extra-terrestrial life should focus on planets where liquid water occurs. 

Around 1.11 times the radius of the earth, Kepler-186f is part of a multi-planet system around the star Kepler-186 which has five planets, one of which is in the centre of the habitable zone. While there have been other discoveries of earth-sized and smaller planets, those planets have been found in orbits that are too close to their host stars for water to exist in liquid form. Findings taken from three years of data show that the intensity and spectrum of radiation from Kepler-186f indicate that the planet could have an earth-like atmosphere and water at its surface which is likely to be in liquid form. 

Kepler-186 is a dwarf star, much smaller and cooler than the Sun. These stars are numerous in our galaxy and have some features that make them promising places to look for life.

On the other hand, small stars tend to be more active than stars the size of our sun, sending out more solar flares and potentially more radiation toward a planet's surface.

"What makes this finding particularly compelling is that this Earth-sized planet, one of five orbiting this star, which is cooler than the Sun, resides in a temperate region where water could exist in liquid form," says Elisa Quintana of the SETI Institute and NASA Ames Research Centre.

San Francisco State University astronomer Stephen Kane and an international team of researchers announced the discovery on Friday.

"Some people call these habitable planets, which of course we have no idea if they are," said Kane. "We simply know that they are in the habitable zone, and that is the best place to start looking for habitable planets".

Notre Dame astro-physicist Justin R Crepp said "Kepler 186 is an M1-type dwarf star which means it will burn hydrogen forever, so there is ample opportunity to develop life around this particular star and because it has just the right orbital period water may exist in a liquid phase on this planet".

Crepp is building an instrument at Notre Dame named named "iLocater" that will be the first ultra-precise Doppler spectrometer to be fibre-fed and operated behind an adaptive optics system. His instrument, to be installed at the Large Binocular Telescope in Arizona, will identify terrestrial planets orbiting in the habitable zone of nearby M-dwarf stars, much closer to the Sun than Kepler-186, by achieving unprecedented radial velocity precision at near-infrared wavelengths.

After the astronomers were able to confirm that Kepler-186f was a planet, they used the transit information to calculate the planet's size. Kepler-186f is slightly bigger than Earth but the researchers are yet to know about its mass.

Kane said "Having the mass and radii of a planet allows the astronomers to calculate other features such as a planet's average density which can help say whether it's rocky or not. What happens there is that for radii between 1.5 and 2 Earth radii, the planet becomes massive enough that it starts to accumulate a very thick hydrogen and helium atmosphere, so it starts to resemble the gas giants of our solar system rather than anything else that we see as terrestrial".