tagged w/ Light Years
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Who says age is a barrier when it comes to discovery of SuperNova? Story broke out today that a 10-year-old Kathryn Gray made a record-breaking find when she discovered a supernova ...
http://bit.ly/gllmTWWho says age is a barrier when it comes to discovery of SuperNova? Story broke out... more
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Many Earth-like planets orbit sun-like stars
Nearly one-fourth of sun-sized stars, if not more, have planets about the size of our own circling in close orbits, researchers say. The findings pose a challenge to the current theory of planetary formation.
By Thomas H. Maugh II, Los Angeles Times
October 29, 2010
At least one in every four stars like the sun has planets about the size of Earth circling in very close orbits, according to the first direct measurement of the incidence of such planets, researchers said Thursday.
That means that our galaxy alone, with its roughly 200 billion sun-like stars, has at least 46 billion Earth-size planets orbiting close to the stars, and perhaps billions more circling farther out in what scientists call the habitable zone, said astronomer Andrew Howard of UC Berkeley, a coauthor of a paper on the subject published in Friday's edition of the journal Science.
Such planets "are like grains of sand sprinkled on a beach — they are everywhere," Howard said.
The discovery of such a large number of small planets so close to stars is somewhat surprising because it appears to contradict the current theory of planetary formation.
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Current models suggest that most planets are born in the outer regions of alien solar systems by the accretion of dust and other materials. That theory says larger planets are drawn into the inner solar system by gravity, but "small ones are stuck on the outskirts," Howard said. Obviously, he added, the theory "needs something to move them in closer to the host star."
Astronomer David Charbonneau of Harvard University, who was not involved in the new research, noted that "contradictions have become the norm" in the study of extrasolar planets. "We have come to expect surprises. … The planetary formation models haven't been successful as predictive models. There is still a lot more work to do."
Howard worked with Berkeley's Geoffrey Marcy, who has been one of the leaders in discovering extrasolar planets. They used the twin 10-meter Keck telescopes in Hawaii to study 166 G and K stars within 80 light-years of Earth for five years. G stars, like the sun, are yellow. K stars are slightly smaller, orange-red stars.
Howard, Marcy and their colleagues charted the precise movements of the stars to look for slight wobbles in their paths caused by the gravitational influence of planets circling them. That technique allowed them to detect planets ranging in size from three to 1,000 times Earth's mass and orbiting as much as one-quarter of an astronomical unit from the host star. An astronomical unit, the distance of the Earth from the sun, is 93 million miles.
The team found that 1.6% of the stars had giant planets orbiting close in — those the size of Jupiter or larger. About 6.5% had planets of intermediate mass, about 10 to 30 times that of Earth, or similar to the size of Neptune or Uranus. And 11.8% had so-called super-Earths, with masses three to 10 times that of Earth.
Extrapolating, they concluded that 23% of the stars hosted even smaller planets, which could not be detected.
Of course, all these planets so close to their stars are exceedingly hot and are certainly not habitable. But "it is not a huge stretch to speculate that nature probably makes a lot of these planets farther out in orbits that might be habitable," Howard said.Many Earth-like planets orbit sun-like stars
Nearly one-fourth of sun-sized stars,... more
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A new member in a family of planets circling a red dwarf star 20 light-years away has just been found. It's called Gliese 581g, and the 'g' may very well stand for Goldilocks.
link: http://news.discovery.com/space/earth-like-planet-life.htmlA new member in a family of planets circling a red dwarf star 20 light-years away has... more
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Scientists discover monster star
Photo: The massive star is in the Tarantula Nebula, 165,000 light years from our galaxy.
By Moni Basu, CNN
July 21, 2010 5:54 p.m. EDT
(CNN) -- Imagine a star so luminous that it would burn the Earth up if it were anywhere near, a star that outshines the sun as much as the sun outshines the moon. A monster even in the abyss of space.
The star is not some scientist's celestial dream. Astronomers used a Very Large Telescope -- the instrument's official name -- to detect the most massive star discovered to date. In scientific lingo, it's a "hypergiant."
Led by Paul Crowther, professor of astrophysics at England's University of Sheffield, the team of astronomers studied two young clusters of stars, NGC 3603 and RMC 136a.
R136a1, found in the RMC 136a cluster, is 10 million times brighter than the sun and is the heaviest star ever found, Crowther said Wednesday, with a mass that is roughly 265 times more than the sun. It was born even heavier, with a solar mass of 320. Astronomers previously thought 150 to be the upper limit.
Several of the stars studied had surface temperatures of 40,000 degrees, more than seven times hotter than the sun.
R136a1 is rare and resides in another galaxy called the Large Magellanic Cloud. Its home is more than 165,000 light years away from Earth's Milky Way galaxy. As such, said Crowther, it is not visible to the naked eye, nor with a rooftop telescope.
"Owing to the rarity of these monsters, I think it is unlikely that this new record will be broken any time soon," Crowther said.
Crowther's team used the sophisticated infrared equipment on the Very Large Telescope in a European Southern Observatory facility in Chile as well as data collected from the Hubble Space Telescope to detect the colossal star. The telescope is considered the world's "biggest eye on the sky" and is 8 meters (26 feet) in diameter.
The research was published in the current issue of the British scientific journal The Monthly Notices of the Royal Astronomical Society.
"Unlike people, these kind of stars are massive when they are babies," Crowther told CNN. "They lose weight as they get older."
At over a million years old, the star is already middle-aged, Crowther said, and could easily be a poster child for WeightWatchers, having shed a fifth of its initial mass over time because of powerful winds.
In another million years -- a brief life span compared to the sun's 5 billion years of existence -- the giant star will probably explode as a supernova. It won't be noticeable on Earth because it's so far away.
Crowther, excited about the new find, had to find simple terminology to describe it to his 6-year-old son Billy. Billy, in turn, wanted dad to name the monster star after him.
That might have sounded a whole lot better than R136a1, but nonetheless, a star is born.Scientists discover monster star
Photo: The massive star is in the Tarantula... more
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The space telescope of the NASA Spitzer found evidence of a collision between two planets around a young star. The star around which it was identified the impact has "only" 12 million years, much less than the 4 and a half billion years of our solar system, and is located in the constellation of the Peacock (Pavo) at a distance of 100 light years from us. The clash involved a planet large like Mars and one like Mercury, both much smaller than the Earth.The space telescope of the NASA Spitzer found evidence of a collision between two... more
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