Evidence of 'Starquakes' on Neutron Star

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An earthquake can be a pretty awe-inspiring natural event - a testament to the sheer power and size of shifting landmass. But what about seismic activity on a star? NASA's Fermi satellite recently spotted evidence of seismic waves rippling throughout a high-energy neutron star, resulting in an intense "storm" of high-energy blasts.

The star in question, called SGR J1550-5418, is a magnetar - an incredibly dense and highly magnetized neutron star that spins at an exceptionally high speed. The typical neutron star boasts a magnetic pull trillions of times stronger than the Earth's. A magnetar, by comparison, is about 1,000 times more magnetic than that.

Within the last four decades, only 23 magnetars in all have been identified, and among these stars, only three massive flares have ever been seen. The flares were related to "starquakes," in which instability of a neutron's pressing magnetic field literally shakes its surface.

"Fermi's Gamma-ray Burst Monitor (GBM) has captured the same evidence from smaller and much more frequent eruptions called bursts.

Source : nature world news

Half of universe's stars are orphans with no galaxy

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Celestial orphans are relatively small, less massive, cooler than our sun, expert says

New observations from suborbital rocket launches and an orbiting observatory show that as many as half the stars in the universe may be orphans with no galaxy scientists said on Thursday. They found that the dim light these stars produce from the far reaches of the cosmos equals the amount coming from all the galaxies.

'The night sky on a planet around such a star would be profoundly boring and black to human eyes - no other stars, or at least very few, no Milky Way band, only distant galaxies.'                                        - Michael Zemcov, Caltech experimental astrophysicist

The phenomenon of the orphan star has been well known. Astronomers have witnessed tidal streams of stars being stripped away from colliding pairs of galaxies.

The data suggests orphan stars are probably relatively small, less massive and cooler than our Sun, but typical of most stars in the universe, said Caltech experimental astrophysicist Michael Zemcov.

The night sky as seen from Earth is brimming with starlight. But these orphans would be so distant from other stars that a view from one would offer almost complete nothingness.

"The night sky on a planet around such a star would be profoundly boring and black to human eyes - no other stars, or at least very few, no Milky Way band, only distant galaxies. You might be lucky and see your parent galaxy off in the distance like we see Andromeda," Zemcov said.

Zemcov said scientists have traced the origin of galaxies to about 13.2 billion years ago, 500 million years after the Big Bang that created the universe.

"Galaxies have been forming and interacting continuously since then, with a peak in the star formation rate about two billion years after the Big Bang," Zemcov said. "You have enough interactions over enough time, and you end up stripping out a lot of stars."

Source : cbc.ca

Milky Way's Supermassive Black Hole Reveals Identity of Strange Object at Center of Our Galaxy

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 What are Supermassive Black Hole ?

Supermassive black hole (SMBH) is the largest type of black hole, on the order of hundreds of thousands to billions of solar masses. Most—and possibly all—galaxies are inferred to contain a supermassive black hole at their centers.In the case of the Milky Way, the SMBH is believed to correspond with the location of Sagittarius A*.

For years, astronomers have been puzzled by a bizarre object in the center of the Milky Way that was believed to be a hydrogen gas cloud headed toward our galaxy's enormous black hole. Having studied it during its closest approach to the black hole this summer, UCLA astronomers believe that they have solved the riddle of the object widely known as G2.

A team led by Andrea Ghez, professor of physics and astronomy in the UCLA College, determined that G2 is most likely a pair of binary stars that had been orbiting the black hole in tandem and merged together into an extremely large star, cloaked in gas and dust — its movements choreographed by the black hole's powerful gravitational field. The research is published today in the journal Astrophysical Journal Letters.
"We are seeing phenomena about black holes that you can't watch anywhere else in the universe," Ghez added. "We are starting to understand the physics of black holes in a way that has never been possible before."

Ghez, who studies thousands of stars in the neighborhood of the supermassive black hole, said G2 appears to be just one of an emerging class of stars near the black hole that are created because the black hole's powerful gravity drives binary stars to merge into one. She also noted that, in our galaxy, massive stars primarily come in pairs. She says the star suffered an abrasion to its outer layer but otherwise will be fine.

Astronomers had figured that if G2 had been a hydrogen cloud, it could have been torn apart by the black hole, and that the resulting celestial fireworks would have dramatically changed the state of the black hole. "G2 survived and continued happily on its orbit; a simple gas cloud would not have done that," said Ghez, who holds the Lauren B. Leichtman and Arthur E. Levine Chair in Astrophysics. "G2 was basically unaffected by the black hole. There were no fireworks."

Black holes, which form out of the collapse of matter, have such high density that nothing can escape their gravitational pull — not even light. They cannot be seen directly, but their influence on nearby stars is visible and provides a signature, said Ghez, a 2008 MacArthur Fellow.

The image below shows Sagittarius A* — the giant black hole at the center of our galaxy — appears dim in this composite image because very little material is falling into it.

Ghez and her colleagues — who include lead author Gunther Witzel, a UCLA postdoctoral scholar, and Mark Morris and Eric Becklin, both UCLA professors of physics and astronomy — conducted the research at Hawaii's W.M. Keck Observatory, which houses the world's two largest optical and infrared telescopes.

When two stars near the black hole merge into one, the star expands for more than 1 million years before it settles back down, said Ghez, who directs the UCLA Galactic Center Group. "This may be happening more than we thought. The stars at the center of the galaxy are massive and mostly binaries. It's possible that many of the stars we've been watching and not understanding may be the end product of mergers that are calm now."

Ghez and her colleagues also determined that G2 appears to be in that inflated stage now. The body has fascinated many astronomers in recent years, particularly during the year leading up to its approach to the black hole. "It was one of the most watched events in astronomy in my career," Ghez said.

Ghez said G2 now is undergoing what she calls a "spaghetti-fication" — a common phenomenon near black holes in which large objects become elongated. At the same time, the gas at G2's surface is being heated by stars around it, creating an enormous cloud of gas and dust that has shrouded most of the massive star.

Witzel said the researchers wouldn't have been able to arrive at their conclusions without the Keck's advanced technology. "It is a result that in its precision was possible only with these incredible tools, the Keck Observatory's 10-meter telescopes," Witzel said.

The telescopes use adaptive optics, a powerful technology pioneered in part by Ghez that corrects the distorting effects of the Earth's atmosphere in real time to more clearly reveal the space around the supermassive black hole. The technique has helped Ghez and her colleagues elucidate many previously unexplained facets of the environments surrounding supermassive black holes.

The image at the top of the page is a simulation showing the possible behavior of a gas cloud that has been observed approaching the black hole at the center of the Milky Way.

Source :  daily galaxy

Planet-forming lifeline discovered in a binary star system

Artist’s impression of the double-star system GG Tauri-A.

If the feeding process into the system’s inner disk occurs elsewhere, the findings introduce many new potential locations to find exoplanets.

For the first time, researchers using ALMA have detected a streamer of gas flowing from a massive outer disk toward the inner reaches of a binary star system. This never-before-seen feature may be responsible for sustaining a second, smaller disk of planet-forming material that otherwise would have disappeared long ago. Half of Sun-like stars are born in binary systems, meaning that these findings will have major consequences for the hunt for exoplanets.

A research group led by Anne Dutrey from the Laboratory of Astrophysics of Bordeaux, France, used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe the distribution of dust and gas in a multiple-star system called GG Tau-A. This object is only a few million years old and lies about 450 light-years from Earth in the constellation Taurus the Bull.

Like a wheel in a wheel, GG Tau-A contains a large, outer disk encircling the entire system as well as an inner disk around the main central star. This second inner disk has a mass roughly equivalent to that of Jupiter. Its presence has been an intriguing mystery for astronomers since it is losing material to its central star at a rate that should have depleted it long ago.

While observing these structures with ALMA, the team made the exciting discovery of gas clumps in the region between the two disks. The new observations suggest that material is being transferred from the outer to the inner disk, creating a sustaining lifeline between the two.

“Material flowing through the cavity was predicted by computer simulations but has not been imaged before. Detecting these clumps indicates that material is moving between the disks, allowing one to feed off the other,” said Dutrey. “These observations demonstrate that material from the outer disk can sustain the inner disk for a long time. This has major consequences for potential planet formation.”

Planets are born from the material left over from star birth. This is a slow process, meaning that an enduring disk is a prerequisite for planet formation. If the feeding process into the inner disk now seen with ALMA occurs in other multiple-star systems, the findings introduce a vast number of new potential locations to find exoplanets in the future.

The first phase of exoplanet searches was directed at single-host stars like the Sun. More recently, it has been shown that a large fraction of giant planets orbit binary-star systems. Now, researchers have begun to take an even closer look and investigate the possibility of planets orbiting the individual stars of multiple-star systems. The new discovery supports the possible existence of such planets, giving exoplanet discoverers new happy hunting grounds.

“Almost half the Sun-like stars were born in binary systems,” said Emmanuel Di Folco from the Laboratory of Astrophysics of Bordeaux, France. “This means that we have found a mechanism to sustain planet formation that applies to a significant number of stars in the Milky Way. Our observations are a big step forward in truly understanding planet formation.”ast

Amazing picture of Supernova 1987A

Real image SN 1987A located at 1,68,000 light years from earth in Large Magellanic Cloud (Another Galaxy)

you can imagine the power of this supernova by understanding that even it was located at another galaxy it was visible to the naked eye. It was the first supernova that modern astronomers had to observe a SN and to use modern technology in that observation allowing them to gather much more data.

Supernovae are extremwely rare events. About 1 every 200 years is visible and they only last for a month or two.



image of SN 1987A

IF YOU THINK THAT EARTH IS VERY LARGE THEN JUST TAKE A LOOK AT THIS VIDEO

http://www.youtube.com/watch?v=HEheh1BH34Q