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Thursday, December 22, 2011

Neutron Stars


A neutron star is the gravitationally collapsed core of a massive star. When large stars use up all their nuclear fuel, they build up a core of iron as large as the planet Jupiter, containing about 1.44 solar masses of material. Because fusing iron nuclei requires putting in more energy than is produced, nuclear fusion no longer produces the core pressure necessary to prevent the star from collapsing in on itself.
During the last moments of collapse, the giant star's iron core phase changes into neutronium, a state of matter where all the electrons and protons in the iron atoms are fused together to produce nothing but neutrons. Because neutrons are neutral, they do not repel each other like the negatively-charged electron clouds in conventional matter do. Being pushed together by tremendous gravitational energy, the neutronium has similar density to an atomic nucleus, and in fact the entire core can be viewed as a large atomic nucleus. Its source of light and heat cut off, the outer layers of the star fall inwards, then bounce back after slamming against the nearly-incompressible neutronium. The result is a supernova, a process which lasts from days to months.
The end result is a supernova remnant, a neutron star between 1.35 and 2.1 solar masses, with a radius between 20 and 10 km. This is the mass greater than the Sun condensed in the space the size of a small city. The neutron star is so dense that a single teaspoon of its material weighs one billion tonnes (over 1.1 billion tons).
Depending on the neutron star's mass, it may quickly collapse into a black hole, or continue existing practically forever. Different neutron stars include radio pulsars, x-ray pulsars, and magnetars, which are a subcategory of radio pulsars. Most neutron stars are called pulsars because they emit regular pulses of radio waves, through a precise physical mechanism not entirely understood, slowly siphoning energy off their own angular momentum.
Some neutron stars do not emit visible radiation. This is likely because radio pulses are emitted from their poles and the poles of some neutron stars do not face Earth.
X-ray pulsars emit x-rays rather than radio waves, and are powered by extremely hot inflowing matter rather than their own rotation. If enough matter falls into a neutron star, it may collapse into a black hole.

The most intense variety of neutron star is one that comes from a parent star that rotates very rapidly. If the star rotates quickly enough, the rotation speed matches inner convective currents and creates a natural dynamo, pumping the magnetic field of the collapsing star up to tremendous levels. The star is then called a magnetar. A magnetar has a magnetic field similar to that of a trillion stars worth of high-powered neodymium magnets overlapping the same spot.


Thursday, December 15, 2011

Evolution of a Star



It is common knowledge, that a bright star is also the hottest one and the small or dim ones are the coolest stars. Depending on this primary hypothesis, a star is studied for further information about its origin. Stars like Vega, are a huge mass of a cold and dusty clouds made up of gases. The gravitational force causes the gases to contract. The assembling of matter in close formations, leads to a rise in temperature. This rise in temperature leads to a chain of nuclear reactions in the atoms of the components present. The reason why we see luminous bodies in space is because of the energy released during chemical reactions in the stellar area.

The dusty mass consists of a large amount of hydrogen. The nucleus of an hydrogen atom undergoes a nuclear fusion reaction, to transform into helium. This conversion is accompanied by a steady release of a huge amount of energy. This is visible as a radiant light in space. This sequence of events lasts for about 10 billion years in the case of an average or medium-sized star. For instance, the Sun (which is a medium-sized star) is believed to be 5 billion years old and may live on for another 5 billion years.

Once their energy supplying elements deplete, stars slowly fade away. In the dying stages, usually a lot of stars end up as white, small and dense globes called white dwarfs. In some cases, they end up in massive explosions called a supernova, caused by the sudden collapse of a big star. The enormity of these explosions can be understood from the fact that a dying star produces more energy than what the sun can produce in millions of years. These dying stars leave behind a bluish residual mass called a pulsar. Stellar formations are usually enveloped in dense clouds of dust and gas. These cloudy envelopes block the light emitted by the stars. Infrared telescopes specially designed to detect stellar emissions are used by astronomers in such cases.


Once a single evolutionary cycle is completed, the next one begins immediately, in case of stars which end up as a nova or a supernova. The disintegrated stars end up into the constituent elements, which were synthesized earlier during their formation and radiation stages. For example, helium molecules synthesized from the action of hydrogen, returns to the original state. Only this time, the interstellar medium elements formed are heavier than hydrogen, which results in the evolution of a brighter star with the same process. The core remainder of a supernova or nova is called a neutron star. These stars exist as mildly radiating, small bodies of dust, which keep on contracting, After a stipulated time interval, these change into a black hole, from which even light radiations cannot escape. The future of stars which form a white dwarf after disintegration, is still not conclusively known. However, they turn into extremely low radiation bodies which may burn out like cinders.
This is what happens, in the entire life cycle of the stars so far and also in the years to come, as concluded by our astronomers. 

Saturday, December 10, 2011

The New Possible Earth: Kepler 22b








Kepler 22b, the planet which scientists say hold the best hope yet for future human habitation, could have continents, oceans and creatures already living on its surface, they believe.
The new planet was discovered by Nasa’s Kepler space telescope two years ago but new research has identified it as the most similar to our own yet discovered.Kepler 22b has temperatures which average around 72 F (22 Celsius) that might support life.
It also contains the right atmosphere to potentially support life. However, there is a downside: it is 600 light years from Earth.
Kepler 22b is some 600 light years away from earth and it is 2.4 times the size of earth.Dubbed the "Goldilocks Zone", this is the band where temperatures are just right to allow the existence of surface liquid water throughout its orbit.This means the planet could have continents and oceans just like the
Earth, and where there is liquid water, there could also be life, they say.Scientists believe Kepler 22b may not only be habitable, but possibly already even inhabited."This discovery supports the growing belief that we live in a universe crowded with life," said Dr Alan Boss, from the Carnegie Institution for Science in Washington DC, who helped identify the planet from data obtained by the Kepler space telescope.The telescope, launched by the American space agency Nasa, is watching 155,000 stars looking for tiny drops in brightness that betray the presence of planets.The star around which Kepler 22b orbits, in the region of the constellations of Lyra and Cygnus, should you know them, is slightly smaller than the Sun and about 25% less bright.The planet orbits the star in 290 days, at a distance 15% closer than the Earth is from the Sun.It lies right in the centre of the star's habitable zone, where potentially perfect conditions exist for life.






Two other small planets orbiting stars smaller and cooler than the Sun have recently been found at the very edges of their habitable zones. Their orbits more closely resemble those of Mars and Venus.
A report on the discovery will be published by the Astrophysical Journal.Dr Douglas Hudgins, Kepler programme scientist at Nasa headquarters in Washington, said: "This is a major milestone on the road to finding Earth's twin."
The planet was spotted after making a "transit" across the front of its parent star, causing the star's brightness to dip.

Multiverse: The Entire Cosmos



Two hundred years have passed since the research of the Mutiverse has started. Many of us know that we are not the only ones in this universe. 


But only a few agree to the concept of multiple universes. If there can be multiple life forms why cant there be multiple universes in which they exist. Many of us find this as science fiction. But this is beyond science and science fiction.


Nobody found till now that the entire cosmos is within this universe. We can consider this universe as a part of a greater thing. To be more precise, let us see this as the Multiverse. even Albert Einstein believed that the center of the universe can lead to another.


The increase in the dark energy and the expansion of the galaxies is also a possibility for such things.


As you all have known the big bang is the start of the universe. But why cant we assume that the big bang is a instance and not a start. It may be considered as just a phenomenon that occurred  in a part of the mutiverse. 
Prof. Brian Greene stated this himself that the big bang is not just the start.


So if there are multiple universes what would it look like ?


According to many theoretical physicists the physical laws or the basic laws might differ from one universe to the other. For example if our universe is held together by the gravitational force, the other might be held by some unknown force yet to be found out.


Even though we may not live to see such discoveries, we can at least believe that our mankind in future will make such giant leaps. But for now it remains as one of the countless mysteries of nature. 

"Seven Planets " around a new solar system


After a short gap am posting this little discovery of our astronomers.
A new planetary system just like ours has just been discovered! 

Astronomers have discovered a new solar system that appears to have 

almost as many planets as our own. They found up to seven planets 

orbiting a star that is of a similar type to the Sun, including one that is likely 

to be rocky and less than 1.5 times the size of the Earth.

The star, labelled HD 10180, lies 127 light-years away from us in the 

constellation of Hydra, the water snake. Its collection of worlds was 

detected using a giant telescope operated by the European Southern 

Observatory at La Silla on a mountaintop in Chile.

A highly sensitive  “planet hunter” called HARPS was used to analyse light 

collected by the telescope’s 3.6-meter wide mirror, or “eye on the sky” over 

six years.

The positions of the planets in the new solar system also follow a similar 

pattern to that generally followed by our own Sun’s family of eight worlds, 

with each planet in order from the star being roughly twice as far as its 

sibling.

Tuesday, November 1, 2011

Prof. Brian Greene about Multiple Universes



Prof. Brian Greene, a theoretical physicist, explains the possibilities of an elegant Multiverse.

Monday, October 31, 2011

Quantum Teleportation


Quantum teleportation is not the same as the teleportation most of us know from science fiction, where an object (or person) in one place is “beamed up” to another place where a perfect copy is replicated. In quantum teleportation two photons or ions (for example) are entangled in such a way that when the quantum state of one is changed the state of the other also changes, as if the two were still connected. This enables quantum information to be teleported if one of the photons/ions is sent some distance away.
In previous experiments the photons were confined to fiber channels a few hundred meters long to ensure their state remained unchanged, but in the new experiments pairs of photons were entangled and then the higher-energy photon of the pair was sent through a free space channel 16 km long. The researchers, from the University of Science and Technology of China and Tsinghua University in Beijing, found that even at this distance the photon at the receiving end still responded to changes in state of the photon remaining behind. The average fidelity of the teleportation achieved was 89 percent.
The distance of 16 km is greater than the effective aerosphere thickness of 5-10 km, so the group's success could pave the way for experiments between a ground station and a satellite, or two ground stations with a satellite acting as a relay. This means quantum communication applications could be possible on a global scale in the near future.
The public free space channel was at ground level and spanned the 16 km distance between Badaling in Beijing (the teleportation site) and the receiver site at Huailai in Hebei province. Entangled photon pairs were generated at the teleportation site using a semiconductor, a blue laser beam, and a crystal of beta-barium borate (BBO). The pairs of photons were entangled in the spatial modes of photon 1 and polarization modes of photon 2. The research team designed two types of telescopes to serve as optical transmitting and receiving antennas.
The experiments confirm the feasibility of space-based quantum teleportation, and represent a giant leap forward in the development of quantum communication applications.

Sunday, October 16, 2011

Helix Nebula




The composite picture is a seamless blend of ultra-sharp NASA Hubble Space Telescope (HST) images combined with the wide view of the Mosaic Camera on the National Science Foundation's 0.9-meter telescope at Kitt Peak National Observatory, part of the National Optical Astronomy Observatory, near Tucson, Ariz. Astronomers at the Space Telescope Science Institute assembled these images into a mosaic. The mosaic was then blended with a wider photograph taken by the Mosaic Camera. The image shows a fine web of filamentary "bicycle-spoke" features embedded in the colorful red and blue gas ring, which is one of the nearest planetary nebulae to Earth.


Because the nebula is nearby, it appears as nearly one-half the diameter of the full Moon. This required HST astronomers to take several exposures with the Advanced Camera for Surveys to capture most of the Helix. HST views were then blended with a wider photo taken by the Mosaic Camera. The portrait offers a dizzying look down what is actually a trillion-mile-long tunnel of glowing gases. The fluorescing tube is pointed nearly directly at Earth, so it looks more like a bubble than a cylinder. A forest of thousands of comet-like filaments, embedded along the inner rim of the nebula, points back toward the central star, which is a small, super-hot white dwarf.


The tentacles formed when a hot "stellar wind" of gas plowed into colder shells of dust and gas ejected previously by the doomed star. Ground-based telescopes have seen these comet-like filaments for decades, but never before in such detail. The filaments may actually lie in a disk encircling the hot star, like a collar. The radiant tie-die colors correspond to glowing oxygen (blue) and hydrogen and nitrogen (red).


Valuable Hubble observing time became available during the November 2002 Leonid meteor storm. To protect the spacecraft, including HST's precise mirror, controllers turned the aft end into the direction of the meteor stream for about half a day. Fortunately, the Helix Nebula was almost exactly in the opposite direction of the meteor stream, so Hubble used nine orbits to photograph the nebula while it waited out the storm. To capture the sprawling nebula, Hubble had to take nine separate snapshots.


Planetary nebulae like the Helix are sculpted late in a Sun-like star's life by a torrential gush of gases escaping from the dying star. They have nothing to do with planet formation, but got their name because they look like planetary disks when viewed through a small telescope. With higher magnification, the classic "donut-hole" in the middle of a planetary nebula can be resolved. Based on the nebula's distance of 650 light-years, its angular size corresponds to a huge ring with a diameter of nearly 3 light-years. That's approximately three-quarters of the distance between our Sun and the nearest star.


The Helix Nebula is a popular target of amateur astronomers and can be seen with binoculars as a ghostly, greenish cloud in the constellation Aquarius. Larger amateur telescopes can resolve the ring-shaped nebula, but only the largest ground-based telescopes can resolve the radial streaks. After careful analysis, astronomers concluded the nebula really isn't a bubble, but is a cylinder that happens to be pointed toward Earth.

Saturday, October 8, 2011

Heaviest known Blackhole



Seattle — Astronomers led by Karl Gebhardt of The University of Texas at Austin have measured the most massive known black hole in our cosmic neighborhood by combining data from a giant telescope in Hawai'i and a smaller telescope in Texas.
The result is an ironclad mass of 6.6 billion suns for the black hole in the giant elliptical galaxy M87. This enormous mass is the largest ever measured for a black hole using a direct technique. Given its massive size, M87 is the best candidate for future studies to "see" a black hole for the first time, rather than relying on indirect evidence of their existence as astronomers have for decades.
Gebhardt, the Herman and Joan Suit Professor of Astrophysics, led a team of researchers using the 8-meter Gemini North telescope in Hawaii to probe the motions of stars around the black hole in the center of the massive galaxy M87.
The results will be presented in a news conference today at the 217th meeting of the American Astronomical Society in Seattle. Two papers detailing the results will be published soon in The Astrophysical Journal.
University of Texas at Austin graduate student Jeremy Murphy has used the Harlan J. Smith Telescope at the university's McDonald Observatory in West Texas to probe the outer reaches of the galaxy — the so-called "dark halo." The dark halo is a region surrounding the galaxy filled with "dark matter," an unknown type of mass that gives off no light but is detectable by its gravitational effect on other objects.
In order to pin down the black hole's mass conclusively, Gebhardt says, one must account for all the components in the galaxy. Studies of the central and outermost regions of a galaxy are necessary to "see" the influence of the dark halo, the black hole and the stars. But when all of these components are considered together, Gebhardt says, the results on the black hole are definitive, meeting what he calls the "gold standard" for accurately sizing up a black hole.
Gebhardt used the Near-Infrared Field Spectrograph on Gemini to measure the speed of the stars as they orbit the black hole. The study was improved by Gemini's use of "adaptive optics," a system that compensates, in real time, for shifts in the atmosphere that can blur details seen by telescopes on the ground.
Together with the telescope's large collecting area, the adaptive optics system allowed Gebhardt and graduate student Joshua Adams to track the stars at M87's heart with 10 times greater resolution than previous studies.
"The result was only possible by combining the advantages of telescope size and spatial resolution at levels usually restricted to ground and space facilities, respectively," Adams says.
Astronomer Tod Lauer of the National Optical Astronomy Observatory, which was also involved in the Gemini observations, says "our ability to obtain such a robust black hole mass for M87 bodes well for our ongoing efforts to hunt for even larger black holes in galaxies more distant than M87."
Graduate student Jeremy Murphy used a different instrument to track the motions of stars at the outskirts of the galaxy. Studying the stars' movements in these distant regions gives astronomers insight into what the unseen dark matter in the halo is doing. Murphy employed an innovative instrument called VIRUS-P on McDonald Observatory's Harlan J. Smith Telescope.
Studying the distant edges of a galaxy, far from the bright center, is a tricky business, Gebhardt says.
"That has been an enormous struggle for a long time, trying to get what the dark halo is doing at the edge of the galaxy, simply because, when you look there, the stellar light is faint," he says. "This is where the VIRUS-P data comes in, because it can observe such a huge chunk of sky at once."
This means the instrument can add together the faint light from many dim stars and add them together to create one detailed observation. This kind of instrument is called an "integral field unit spectrograph," and VIRUS-P is the world's largest.
"The ability of VIRUS-P to dig deep into the outer halo of M87 and tell us how the stars are moving is impressive," Murphy says. "It has quickly become the leading instrument for this type of work."
The combined Gemini and McDonald data have allowed the team to pinpoint the mass of M87's black hole at 6.6 billion suns. But measuring such a massive black hole is only one step toward a greater goal.
"My ultimate goal is to understand how the stars assembled themselves in a galaxy over time," Gebhardt says.
"How do you make a galaxy? These two datasets probe such an enormous range, in terms of what the mass is in the galaxy. That's the first step to answering this question. It's very hard to understand how the mass accumulates unless you know exactly what's the distribution of mass: how much is in the black hole, how much is in the stars, how much is in the dark halo."
Today's conclusions also hint at another tantalizing possibility for the future: the chance to actually "see" a black hole.
"There's no direct evidence yet that black holes exist," Gebhardt says, "zero, absolutely zero observational evidence. To infer a black hole currently, we choose the 'none of above' option. This is basically because alternative explanations are increasingly being ruled out."
He says the black hole in M87 is so massive that astronomers someday may be able to detect its "event horizon" — the edge of a black hole, beyond which nothing can escape. The event horizon of M87's black hole is about three times larger than the orbit of Pluto — large enough to swallow our solar system whole.
Though the technology does not yet exist, M87's event horizon covers a patch of sky large enough to be imaged by future telescopes. Gebhardt says future astronomers could use a world-wide network of submillimeter telescopes to look for the shadow of the event horizon on a disc of gas that surrounds M87's black hole.

Saturday, September 24, 2011

Super Earth


Astronomers on Monday announced the discovery of 50 new planets circling 


stars beyond the sun, including one “super-Earth” that is the right distance 


from its star to possibly have water.


“If we are really, really lucky, this planet could be a habitat” like Earth, said 


Lisa Kaltenegger of the Max Planck Institute for Astronomy in Heidelberg, 


Germany.


The planet, dubbed HD85512b, circles an orange star somewhat smaller and 


cooler than our sun about 36 light-years away. The star, HD85512, is visible in 


the southern sky in the constellation Vela.


The newly found planet circles this star every 59 days, putting it at the edge 


of the “habitable zone” where water could exist if atmospheric conditions 


were right.


In a teleconference, Kaltenegger said that the planet is at the warm edge of 


its star’s habitable zone, as if “standing next to a bonfire.” That means the 


planet would require a lot of cloud cover — which reflects starlight — to keep 


the surface cool enough to prevent any water from boiling, she said.


Astronomers have not determined whether the new super-Earth is rocky like 


the Earth or gassy like Jupiter, let alone whether it has an atmosphere. The 


new super-Earth is 3.5 times the mass of Earth.


Astronomers inferred the existence of the planet by watching its star wobble 


ever so slightly. The speed of the wobble indicated the existence of a planet 


tugging at the star.


This “radial velocity” technique has been productive, offering astronomers 


working at La Silla Paranal Observatory in Chile evidence of the 50 new 


“exoplanets” announced Monday. The planet-hunting instrument, called 


HARPS, are operated by the European Southern Observatory.


Sixteen of the new planets announced Monday, including the new super-Earth, 


are of the right mass to be made of rock instead of gas.


“We are building up a target list of super-Earths in the habitable zone,” 


Kaltenegger said.


To determine whether the planet has an atmosphere, astronomers need to 


capture an image of the planet — which they have not done — and analyze the 


light for signs of water, carbon dioxide and other gases. No existing telescope 


is sensitive enough for that task.


But a new telescope to begin construction next year, the European Extremely 


Large Telescope, will be up to the task, said Markus Kissler-Patig of the 


European Southern Observatory. It will be “technically capable of finding life 


around the nearest stars,” he said, by analyzing the atmosphere of exoplanets. 


The new super-Earth is a “prime target” for the new telescope.


Since 1995, astronomers have found more than 600 planets beyond Earth, 


according to a catalog.


In the accelerating race to bag and tag planets outside our solar system, 


HD85512b marks the second super-Earth found at the right distance from its 


star to possibly hold water, considered a vital ingredient for life. The first, 


called Gliese 581d, was discovered by the same telescope in Chile in 2007.

Friday, September 16, 2011

Feeding Frenzy of Draco Constellation


An artistic image of the black hole

 A monster black hole shredded a Sun-like star, producing a strangely long-lasting flash of gamma rays that probably won't be seen again in a million years..

That is definitely not the norm for gamma ray bursts, energetic blasts that typically flare up and end in a matter of seconds or milliseconds, often the sign of the death throes of a collapsing star.

"This is truly different from any explosive event we have seen before," said Joshua Bloom of the University of California-Berkeley, a co-author of research on the blast published in the journal Science.

Initially spied by NASA's Swift spacecraft, which is trolling the universe for gamma ray bursts, this particular flash has lasted more than two months and is still going on, Bloom said in a telephone interview.

What makes this even stranger is that the black hole, located in the constellation Draco (The Dragon) about 4 billion light years, or 24 sextillion miles (38.62 sextillion km) -- 24 followed by 21 zeroes -- from Earth, was sitting quietly, not eating much, when a star about the mass of our Sun moved into range.

"We have this otherwise dormant black hole, not gobbling up an appreciable amount of mass, and along comes this star which just happens to be on some orbit which puts it close to the black hole," Bloom said.

FEEDING FRENZY

"This was a black hole which was otherwise quiescent and it sort of has an impulsive feeding frenzy on this one star," he said.

Bloom figures this may happen once per black hole per million years.

This kind of behavior is different from what active black holes generally do, which is to suck in everything their vast gravity can pull in, even light. Most galaxies, including our Milky Way, are thought to harbor black holes in their hearts.

Black holes are invisible, but astronomers can infer their existence because the material they pull in lights up before it gets sucked in.

In this case, though, the black hole feasted on one star -- about the same mass as our Sun -- with such relish that it tore the star apart before gulping it down. As it did so, the black hole emitted powerful gamma ray jets from its center as bits of the dying star were turned into energy.

The black hole's gravitational pull was so great that it exerted what's called a tidal disruption on the passing star.

Astronomers could use this observation to help them learn more about how black holes grow, Bloom said.

"We still don't understand how black holes and the universe grow," he said. "We think most black holes start off as being no more than the mass of our Sun ... How they go from 10 solar masses to a billion solar masses is critical."

There is a strong connection between the mass of black holes and the mass of the galaxies that host them, with black holes feeding on gas and stars that come near.

Black hole


A black hole is an (almost invisible) body in space, created most likely from a collapsed red super giant star, that is so dense that neither light nor matter can escape its gravitational pull.
Inside a star there is a constant battle between inward pressure from gravity, and outward pressure from heat. If you were to throw an unopened can of soda into a fire, the beverage would expand from the heat and explode. This is the same principle at work when a star is burning, its heat is generating great outward pressure but this constant explosion is matched by gravity that is equally strong, thus a star maintains its shape and size.
When a star nears the end of its life it cools off slowly and the outwards pressure grows weaker and weaker as the temperature of the star drops. When the outward pressure from the heat is nearly gone, the inward pressure of gravity still remains and is determined by the size of the star. It is theorized that when a star roughly ten times the size of our sun nears the end of its life, it shrinks as its own gravity slowly pulls it in, but as it becomes more and more dense the gravity becomes stronger.
The gravity becomes so intense that not even light can escape it. If you have ever watched water swirling down a drain, then you have a pretty good idea what happens as a black hole pulls things in. As matter and light approach the vicinity of a black hole they are slowly drawn in. If they are not headed straight for the spacial anomaly then they are taken into a violent and unstable orbit around the black hole until finally the orbit falls apart and it is sucked down by the immense gravity.
The size of the black hole is determined by the mass of the collapsed star. The critical radius of a non-rotating black hole is called the Schwarzschild radius, called after the German astronomer Karl Schwarzschild (1873-1916) who investigated the problem in 1916 on the basis of Einstein's theory of general relativity. According to general relativity the gravitation of a black hole bends space and time to such an extent where they broken down into a dimensionless body of infinite density.
The boundary around the collapsed star having this radius is referred to as the 'event horizon'. Anything, whether it be light or matter passing this boundary will be forever lost within the black hole with no chance of escape. What happens beyond the event horizon nobody can tell, because all the laws of physics break down and no longer apply. There are many theories but little proof to support them.
Black holes can't be seen, as they do not emit any electromagnetic radiation*. But they can be detected because of their affects on the surrounding stars.
In a binary star system, Cygnus X-1, (where the primary is a normal star of approximately 30 solar masses) due to Doppler shifts from the system it is believed that there is a companion of approximately 10 to 15 solar masses orbiting the primary. There are X-ray emissions from the system usually associated with an 'accretion disk' (a hot, dense disk of gas from the primary star spiraling down into the compact object orbiting the primary). There is evidence indicating that the X-rays are being emitted from the orbiting companion. Due to the mass of the companion object it is thought that it is a black hole.
Evidence of black holes is mounting, and it is now believed that most galaxies of a large enough size and possibly our own have a black hole at their centre.
* It is now known that black holes emit what is called Hawking Radiation, this is a complex process but for those who are interested, here is a brief explanation. Virtual particle pairs are constantly being created near the horizon of the black hole, as they are everywhere. Normally, they are created as a particle-antiparticle pair and they quickly annihilate each other. But near the horizon of a black hole, it's possible for one to fall in before the annihilation can happen, in which case the other one escapes as Hawking radiation.

Thursday, September 8, 2011

Space Storm Tracked from Sun to Earth


For the first time, a spacecraft far from Earth has turned and watched a solar storm engulf our planet. The movie, released today during a NASA press conference, has galvanized solar physicists, who say it could lead to important advances in space weather forecasting.

“The movie sent chills down my spine,” says Craig DeForest of the Southwest Researcher Institute in Boulder, Colorado. “It shows a CME swelling into an enormous wall of plasma and then washing over the tiny blue speck of Earth where we live. I felt very small.”
CMEs are billion-ton clouds of solar plasma launched by the same explosions that spark solar flares. When they sweep past our planet, they can cause auroras, radiation storms, and in extreme cases power outages. Tracking these clouds and predicting their arrival is an important part of space weather forecasting.
“We have seen CMEs before, but never quite like this,” says Lika Guhathakurta, program scientist for the STEREO mission at NASA headquarters. “STEREO-A has given us a new view of solar storms.”
STEREO-A is one of two spacecraft launched in 2006 to observe solar activity from widely-spaced locations. At the time of the storm, STEREO-A was more than 65 million miles from Earth, giving it the “big picture” view other spacecraft in Earth orbit lack.
When CMEs first leave the sun, they are bright and easy to see. Visibility is quickly reduced, however, as the clouds expand into the void. By the time a typical CME crosses the orbit of Venus, it is a billion times fainter than the surface of the full Moon, and more than a thousand times fainter than the Milky Way. CMEs that reach Earth are almost as gossamer as vacuum itself and correspondingly transparent.
“Pulling these faint clouds out of the confusion of starlight and interplanetary dust has been an enormous challenge,” says DeForest.
Indeed, it took almost three years for his team to learn how to do it. Footage of the storm released today was recorded back in December 2008, and they have been working on it ever since. Now that the technique has been perfected, it can be applied on a regular basis without such a long delay.
Alysha Reinard of NOAA’s Space Weather Prediction Center explains the benefits for space weather forecasting:
“Until quite recently, spacecraft could see CMEs only when they were still quite close to the sun. By calculating a CME’s speed during this brief period, we were able to estimate when it would reach Earth. After the first few hours, however, the CME would leave this field of view and after that we were ‘in the dark’ about its progress.”
“The ability to track a cloud continuously from the Sun to Earth is a big improvement,” she continues. “In the past, our very best predictions of CME arrival times had uncertainties of plus or minus 4 hours,” she continues. “The kind of movies we’ve seen today could significantly reduce the error bars.”
The movies pinpoint not only the arrival time of the CME, but also its mass. From the brightness of the cloud, researchers can calculate the gas density with impressive precision. Their results for the Dec. 2008 event agreed with actual in situ measurements at the few percent level. When this technique is applied to future storms, forecasters will be able to estimate its impact with greater confidence.
At the press conference, DeForest pointed out some of the movie’s highlights: When the CME first left the sun, it was cavernous, with walls of magnetism encircling a cloud of low-density gas. As the CME crossed the Sun-Earth divide, however, its shape changed. The CME “snow-plowed” through the solar wind, scooping up material to form a towering wall of plasma. By the time the CME reached Earth, its forward wall was sagging inward under the weight of accumulated gas.
The kind of magnetic transformations revealed by the movie deeply impressed Guhathakurta: “I have always thought that in heliophysics understanding the magnetic field is equivalent to the ‘dark energy’ problem of astrophysics. Often, we cannot see the magnetic field, yet it orchestrates almost everything. These images from STEREO give us a real sense of what the underlying magnetic field is doing.”
All of the speakers at today’s press event stressed that the images go beyond the understanding of a single event. The inner physics of CMEs have been laid bare for the first time — a development that will profoundly shape theoretical models and computer-generated forecasts of CMEs for many years to come.
“This is what the STEREO mission was launched to do,” concludes Guhathakurta, “and it is terrific to see it live up to that promise.”

Dark Energy


Dark energy is perhaps the most mysterious thing in the cosmos, and yet it accounts for 73% of the observable universe. What's more, the amount of dark energy seems to be increasing...and that could ultimately rip apart the entire universe.
For the purposes of this post, I am going to be treating dark energy in much the same way astrophysicists do - as the current best explanation for certain features of the universe, albeit one that is still not well understood. 
The question we'll be looking at is what dark energy might mean for the future of the universe. One thing we do know about it is that it appears to have a constant density throughout the universe over time. Since the universe is expanding, that means the amount of dark energy has to in some way increase to keep up with it - in fact, since so much of the expanding universe is empty space, it means that the proportion of stuff (that's a technical term) in the universe that is dark energy will increase over time - and it's already a pretty huge percentage of that.
The simple explanation for that is that dark energy is somehow a feature of space-time itself, so it expands in kind as the universe expands. That means that the "energy" part of dark energy is a misnomer, but that's the least of our worries. Assuming this is true, we can then say that dark energy is associated with negative pressure, meaning that it acts as a repulsive force driving the expansion of the universe.
In this conception, dark energy is basically just "the cost of having space", meaning that any given volume of space requires a certain amount of dark energy in order to, well, exist. (I know this is vague. There's still a lot we don't know.) As far as cosmologists can tell, the density of dark energy and the pressure of dark energy are in a 1:1 ratio - or, since the pressure of dark energy is negative, a 1:-1 ratio. This is referred to as the equation of state for dark energy, and so the commonly accepted value is -1.
So here's the question: will that -1 stay the same for the rest of the universe's existence? Right now, we have no idea, but we do have a sense of what would happen if it did change. If the density of dark energy decreased over time, that would slow down the rate of expansion - if the ratio dropped made it to -1/3, then the expansion would cease entirely. That would potentially lead to the Big Crunch, in which we see a reversal of the Big Bang. That was once the most popular scenario among astrophysicists for the end of the universe, but it's only possible if the dark energy density decreases.
But what if the density of dark energy increased? As it stands, the universe will just keep on expanding forever. Is there a more extreme fate than that? Oh, you'd better believe it. If the ratio dropped still further to -2 or -3, the dark energy density would approach infinity within a finite amount of time.
So what does that mean? Well, remember that the observable universe is just whatever in the larger universe has had enough time for its light to reach Earth, and the expansion of the universe means that some parts of the universe have moved forever beyond our gaze. Now imagine everything is pulled so far apart by the cosmic expansion that each individual bubble of observable universe is no larger than a galaxy, or the solar system, or our planet, or the room around you...or even down to the individual atoms.
That is what infinity density means, and it would cause what's known as the Big Rip, in which all structures in the universe down to the subatomic particles get torn apart. If the ratio dropped to even just -1.5, the universe would suffer this fate within the next 22 billion years.
That's not a cheery thought, but a miniature version of this process could end up doing the universe a world of good. If the ratio of pressure and density of dark energy can be variable throughout the universe, then it would be possible for the cosmos to experience Little Rips, in which only certain parts of the universe get torn apart. This would actually work to "reboot" the entropy of the universe, as all the newly split apart material can begin again the process of forming stars and galaxies.

Dr.Michio Kaku about alien civilizations

Dr.Michio Kaku describes the three types of alien civilizations.....

Wednesday, September 7, 2011

Dr.Michio Kaku on Multiverse

Let us hear the info on multiverse theory from Dr.Michio Kaku, Theoretical Physicst... He explains us about the  cosmos and the dark energy that leads to the concept of existence of multiple universes.

Monday, September 5, 2011

Aristotle’s Laws of Thought

Aristotle's "Laws of Thought" date back to the earliest days of Western Philosophy. They shape the basic structure of Western philosophy, science, and its overall worldview - the worldview that can so puzzle many non-Westerners. Many philosophers who followed Aristotle, such as Locke, Leibnitz and Schopenhauer, have modified and enhanced his principles. However, the initial intent has remained the same. These laws are fundamental logical rules, with a long tradition in the history of philosophy, which together define how a rational mind must think. To break any of the laws of thought (for example, to contradict oneself) is to be irrational by definition. These three classic laws of thought were fundamental to the development of classical logic. They are:
  • Law of identity - an object is the same as itself: “A is A”

  • Law of noncontradiction - contradictory statements cannot both at the same time be true, e.g. the two propositions "A is B" and "A is not B" are mutually exclusive.

  • Law of excluded middle - Everything must either be or not be. There is no in-between.
These are self-evident logical principles - axioms that cannot be proved (or disproved), but must be accepted (or rejected) a priori. Other postulates could be substituted for them, and in fact have been in other traditions such as Buddhism, which celebrates contradiction. Even Greek philosophy before Aristotle (and Parmenides, who proposed similar laws) did not always embrace these concepts. But practically everything we know of traditional Western Philosophy and Logic embodies these principles. Preceding Aristotle by over a century, Heraclitus believed that contradictions were necessary - that their existence was essential to a thing's identity:
"Not only could it be stated that identity is the strife of oppositions but that there could be no identity without such strife within the entity."
He argued that because all things change, they must have already had in them "that which they were not". Only the existence of such contradictions could account for the change we see in the world. For example,
"Cold things grow warm; warm grows cold; wet grows dry; parched grows moist."
The defenders of Aristotle’s three laws of thought quickly learned that they had to establish the context for the application of these laws, because they were frequently assailed with counter-examples that seemed to violate them. It became clear that the laws could not be employed loosely or in poorly defined conditions. So, they began to require a “definite logic” model. In this model, the terms and the expressions formed from these terms must be clearly definable and knowable. But this ideal is rarely achieved in the real world, and we are forced to make assertions about things in less than precise, fuzzy terms. Not until the creation of Mathematical Logic by Boole in the 19th century, and later Russell and others, was logic able to refine its expression with mathematical, perfectly clear terms and operations.

This development in logic admirably suited the predispositions of the Western mind. Western philosophy to a very large extent has been founded upon the Laws of Thought and similar ground rules. We believe that our thinking should strive to eliminate ideas that are vague, contradictory, or ambiguous, and the best way to accomplish this, and thereby ground our thinking in clear and distinct ideas, is to strictly follow laws of thought.

In spite of how dominant these laws of thought have been, they have not been without their critics, and philosophers from Heraclitus to Hegel have leveled powerful arguments against them. But the issue does not seem to be whether the laws are applicable or not, but where and when are they applicable? Certainly, the laws of thought have a place, but what is that place? As Walt Whitman wrote in “Song of Myself”:
"Do I contradict myself?
Very well, then, I contradict myself.
(I am large, I contain multitudes.)"
Also as Nagarjuna, one of the fathers of Buddhism, wrote in "Verses on the Middle Way":
"Everything is real and not real.
Both real and not real.
Neither real nor not real.
That is Lord Buddha's teaching."
The time to abandon strict laws of thought arises when we are beyond the realm to which ordinary logic applies, or as when “the sphere of thought has ceased, the nameable ceases.” A similar sentiment is expressed by Wittgenstein's assertion in the Tractatus,
"what can be said at all can be said clearly, and what we cannot talk about we must pass over in silence"
It would be very narrow minded, indeed, as well as barren and joyless, to try to apply these or similar laws to every human experience. However, in the narrow, modest realm of science, whose goal is merely to explain how things work and of what they are made, this type of restricted and disciplined thought is a perfect fit.

Supernova Explosion

Here is a small visual on the explosion of a supernova....

Saturday, September 3, 2011

Diamond Planet.




pulsar-Planet

Pulsars are small spinning stars the size of cities like Cologne that emit a beam of radio waves. As the star spins and the radio beam sweeps repeatedly over Earth, radio telescopes detect a regular pattern of radio pulses.

For the newly discovered pulsar, PSR J1719-1438, the astronomers noticed that the arrival times of the pulses were systematically modulated and concluded that this is due to the gravitational pull of a small orbiting companion, a planet. These modulations can tell astronomers several more things about the companion. First, it orbits the pulsar in just 2 hours and 10 minutes, and the distance between the two objects is 370,000 miles — a little less than the radius of our Sun. Second, the companion is so close to the pulsar that if its diameter was any larger than 37,000 miles — less than half the diameter of Jupiter — it would be ripped apart by the gravity of the pulsar.

“The density of the planet is at least that of platinum and provides a clue to its origin”, said Matthew Bailes from Swinburne University of Technology in Australia.
The team thinks that the planet is the tiny core that remained of a once-massive star after narrowly missing destruction by its matter being siphoned off toward the pulsar. They found the pulsar among almost 200,000 gigabytes of data using special codes on supercomputers at Swinburne University of Technology, at the University of Manchester, United Kingdom, and at the INAF Cagliari Astronomical Observatory, Italy.

The project is part of a systematic search for pulsars in the whole sky involving also the 100-meter Effelsberg radio telescope of the Max Planck Institute for Radio Astronomy (MPIfR) in the Northern Hemisphere. “This is the largest and most sensitive survey of this type ever conducted,” said Michael Kramer from MPIfR. “We expected to find exciting things, and it is great to see it happening. There is more to come!”

How did the pulsar acquire its exotic companion? And how do we know it’s made of diamond? Pulsar J1719-1438 is a fast-spinning pulsar that’s called a millisecond pulsar. Amazingly, it rotates more than 10,000 times per minute, has a mass of about 1.4 times that of our Sun, but is only 12 miles in radius. About 70 percent of millisecond pulsars have companions of some kind: Astronomers think it is the companion that, as a star, transforms an old, dead pulsar into a millisecond pulsar by transferring matter and spinning it up to a very high speed. The result is a fast-spinning millisecond pulsar with a shrunken companion-most often a white dwarf.

“We know of a few other systems, called ultra-compact low-mass X-ray binaries, that are likely to be evolving according to the scenario above and may likely represent the progenitors of a pulsar like J1719-1438,” said Andrea Possenti, of INAF.

But pulsar J1719-1438 and its companion are so close together that the companion could only be a stripped-down white dwarf, one that has lost its outer layers and more than 99.9 percent of its original mass. This remnant is likely to be largely carbon and oxygen; stars of lighter elements like hydrogen and helium just won’t fit. The density means that this material is certain to be crystalline: that is, a large part of the star may be similar to a diamond.

“The ultimate fate of the binary is determined by the mass and orbital period of the donor star at the time of mass transfer. The rarity of millisecond pulsars with planet-mass companions means that producing such exotic planets is the exception rather than the rule, and requires special circumstances,” said Benjamin Stappers from the University of Manchester.

“The new discovery came as a surprise for us,” said Michael Kramer. “But there is certainly a lot more we’ll find out about pulsars and fundamental physics in the following years.”