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GAMMA RAY ERUPTION IN THE CRAB NEBULA May 11, 2011

Posted by jcconwell in Astronomy, Neutron Stars.
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WASHINGTON (NASA) — The famous Crab Nebula supernova remnant has erupted in an enormous flare five times more powerful than any flare previously seen from the object. On April 12, NASA’s Fermi Gamma-ray Space Telescope first detected the outburst, which lasted six days.

The nebula is the wreckage of an exploded star that emitted light which reached Earth in the year 1054. It is located 6,500 light-years away in the constellation Taurus. At the heart of an expanding gas cloud lies what is left of the original star’s core, a superdense neutron star that spins 30 times a second. With each rotation, the star swings intense beams of radiation toward Earth, creating the pulsed emission characteristic of spinning neutron stars (also known as pulsars).

Apart from these pulses, astrophysicists believed the Crab Nebula was a virtually constant source of high-energy radiation. But in January, scientists associated with several orbiting observatories, including NASA’s Fermi, Swift and Rossi X-ray Timing Explorer, reported long-term brightness changes at X-ray energies.

Since 2009, Fermi and the Italian Space Agency’s AGILE satellite have detected several short-lived gamma-ray flares at energies greater than 100 million electron volts (eV) — hundreds of times higher than the nebula’s observed X-ray variations. For comparison, visible light has energies between 2 and 3 eV.

On April 12, Fermi’s LAT, and later AGILE, detected a flare that grew about 30 times more energetic than the nebula’s normal gamma-ray output and about five times more powerful than previous outbursts. On April 16, an even brighter flare erupted, but within a couple of days, the unusual activity completely faded out.

“These superflares are the most intense outbursts we’ve seen to date, and they are all extremely puzzling events,” said Alice Harding at NASA’s Goddard Space Flight Center in Greenbelt, Md. “We think they are caused by sudden rearrangements of the magnetic field not far from the neutron star, but exactly where that’s happening remains a mystery.”

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Extreme Universe: The Most Massive Neutron Star October 27, 2010

Posted by jcconwell in Astronomy, Extreme Universe, General Relativity, Neutron Stars.
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Using the National Science Foundation’s Green Bank Telescope , astronomers have discovered the most massive neutron star ever, this discovery will offer profound insight  on the limits of neutron stars and the nature of matter under such extreme conditions.

“This neutron star is twice as massive as our Sun. This is surprising, and that much mass means that several theoretical models for the internal composition of neutron stars now are ruled out,” said Paul Demorest, of the National Radio Astronomy Observatory (NRAO). “This mass measurement also has implications for our understanding of all matter at extremely high densities and many details of nuclear physics,” he added.

The neutron star, called PSR J1614-2230 contains twice the mass of the Sun but compressed down into pulsar that is smaller than 20 kilometer   It is estimated cubic inch of material from the star could weigh more than 10 billion  tons. I have two videos below with more details for you.

The first is about the Discovery

The second is about the Instruments

Top 10 Ways the Universe Could Kill Us! July 24, 2009

Posted by kfarley in Asteroid, Astronomy, Cosmology.
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Asteroid Impact

Asteroids and other near-Earth objects (NEOs) come near the Earth more frequently than one would guess. Question: Why don’t we ever hear of these objects hitting the Earth? Answer: Because they don’t. More often than not our atmosphere causes great friction on these solar bodies causing them to burn up. This happens before the asteroids can go through our atmosphere and hit the Earth. Our atmosphere can be a good friend to us – protecting us from solar debris that could potentially hit Earth and end civilization as we know it. If an asteroid were to make it through our atmosphere it becomes classified as a meteor. It is theorized that a large meteor hit the Earth about 65 million years ago wiping out the dinosaurs. According to NASA, a meteor about 1/5 that size will hit the Earth about once or twice every million years. If Earth did get hit by an asteroid of that caliber we would most likely not survive. I haven’t heard of an asteroid that size hitting the Earth in quite some time, maybe we’re overdue. With ≈6.7 billion people in the world your chance of seeing the Earth hit by that size meteor is…well, you do the math. To learn more information on NEOs check out NASA’s FAQs.

Illustration of an asteroid that could have wiped out the dinosaurs.

Illustration of an asteroid that could have wiped out the dinosaurs.

Solar Flare

A solar flare is a huge explosion of energy in the Sun’s atmosphere. Think of it like a giant spike of light and heat that suddenly rises off the surface of the Sun. The rays emitted (mainly X-rays and UV rays) from this explosion are strong enough to disrupt radio communication on Earth! The flares can influence the surface of Earth by having an effect on our weather. Just outside our atmosphere, the flares can present radiation hazards to spacecraft and astronauts. The solar flares can also produce streams of highly energetic particles in our atmosphere. These highly energetic particles help in the production of the beautiful aurora borealis! On the other hand, the radiation from solar flares also pose incredible complications that could arise during manned missions to Mars, the Moon, or other space travel. Satellites’ orbital paths can also be disrupted by the solar flares. Kind of a catch-22, amazing Northern lights produced but also possible space travel limit. Hmm…

Aurora borealis co-created by solar flares.

Aurora borealis co-created by solar flares.

Supernova

Ever had someone shine a flashlight in your eyes? Not very nice, huh? Think of shining a light in your eyes a billion times brighter! A supernova is just that – an exploding star billions of times brighter that our Sun. After the core of a star collapses it emits great energy as a flash of growing intensity before fading back out of sight. If a supernova was close enough and aimed toward our solar system, it could wipe out our atmosphere. Our planet would overheat from UV rays causing mass extinction. It’s messy too. The supernova will throw large clouds of dust and gas into space that could exceed 10 times the mass of our Sun. We should be thankful for supernovae in a way. It is hypothesized supernovae created the heavier elements such as gold, iron, and uranium found here on Earth.

Supernova.

Supernova.

Gamma Ray Burst

Gamma ray bursts (GRBs) are flashes of gamma rays that last from fractions of a second to almost an hour. They normally last a few seconds and usually come from outside our galaxy. They are the most luminous (electromagnetic) events that occur in the universe. GRBs often have an afterglow affect as longer wavelengths travel from the blast. The blast from a GRB in our galaxy would definitely cause mass extinction from the intense rays that would encompass our planet. It is hypothesized such an event caused the mass planetary extinction on Earth about 444 million years ago. A GRB depleted the ozone layer leaving our planet helpless to direct UV rays that heated and kill organisms until food chains were depleted.

P.S. Gamma rays gave the Hulk his powers (I think that is fictional though).

Illustration of a gamma ray burst hitting a planet like Earth.

Illustration of a gamma ray burst hitting a planet like Earth.

Black hole

Black holes are areas in space in which the gravitational field is so incredible that nothing can escape its pull. Not even light can be reflected from this object, hence its name. It is virtually impossible to escape a black hole once its immense gravitational pull has a hold of you. The point of no return at a black hole is called the horizon. It is an area just outside a black hole where the gravitational pull begins. Once you hit the horizon of a black hole your fate is sealed and escape from the black hole is futile. Knowing not even light can escape the pull of the black hole, you would have to travel faster than the speed of light to escape. If you were to see an object being pulled into a black hole (assuming the object can still reflect light), it would become extremely distorted. The gravitational pull is so intense, the part of the object entering the black hole first would stretch out of normal proportions. For example, if you were floating through space with your arms in front of you (Superman-style) and began to be sucked into a black hole, your arms would stretch out incredibly long before the rest of your body. Black holes are also very massive. They can range anywhere from 10 times to a million times the mass of our Sun. Currently, there are no known black holes in our galaxy. This known with the fact our space travel is limited to our Moon, you are probably safe from a black hole fate.

Illustration of what a black hole over the Milky Way might look like.

Illustration of what a black hole over the Milky Way might look like.

Death of Sun

The Sun goes through different stages during its life cycle. It’s about halfway through the “main sequence” before it goes into a different star phase. The Sun will most likely turn into a Red Giant star peaking at its highest luminosity. The Sun will then start to burn out as it turns into a small dwarf star. The Sun won’t turn into a Red Giant for another 5 billion years or so. A more immediate problem, as the Sun moves toward the next stage it becomes gradually warmer. It will get really hot. Life on Earth most likely won’t make it to the Red Giant stage. The Earth will warm up to the point where life will not be sustainable. The Sun has slowly been warming up ever since its birth. The Sun used to not be as hot, one of the reasons life didn’t always exist on the Earth. Just as the warmth of the Sun allowed life on Earth, it will also take it away.

The life cycle of our Sun.

The life cycle of our Sun.

Heat Death of Universe

The heat death of the universe occurs as all the stars and other universal matter continues to expand and uses up its energy or “burns out.” It’s like letting a candle burn and not blowing it out. Eventually it’s going to use up the wax and wick until it can’t burn anymore. The universe runs on “free” energy that is not endless. At some point the fuel for the universe will run out cutting of the energy for the cosmic bodies that give us life (namely our Sun). This probably won’t be happening anytime soon. It’s estimated the energy will run out after black holes vanish in about 10100 years (according to Hawking’s radiation). That’s one big candle!

The flame of life.

The flame of life.

The Big Rip

Just like how it sounds, all matter of the universe will be ripped apart.  We’ve all heard that the universe is expanding.  What would happen if the expansion increased at an accelerated rate?  If the universe expanded much faster than it is now, all the galaxies, stars, planets, dust, etc. would be ripped apart!  Think of it like a twizzlers.  If you pull slowly you can stretch out the twizzlers pretty far.  If you stretch too fast the twizzlers will just snap in half.  This is a possibility for our universe.  The hands pulling on our universe is something called dark energy.  Dark energy is a hypothetical energy that saturates all our universe.  It is theorized it helps our universe expand – at an accelerating pace.  This means the expansion is moving at a faster and faster rate as time goes by.  Eventually the universe will reach that point where it is pulling to fast, ripping apart everything.  What happens when everything is ripped apart and away from each other?  No one knows.

The Big Rip.

The Big Rip.

Cannibal Galaxies

Cannibal galaxies occur when a smaller galaxy is eaten by a larger galaxy! Natural selection at its best. Galaxies are gravitationally bound collections of stars, stellar bodies such as planets, space dust, and other objects. You are probably most familiar with the Milky Way galaxy (you should know this one, we live in it). Scientists can now detect our Milky Way galaxy is currently tearing apart and engulfing the Sagittarius galaxy as you read this! Closer to home than you might have expected. I guess we are saved this time but poor little Sagittarius galaxy…

Larger galaxy engulfing a smaller galaxy. (Swinburne)

Larger galaxy engulfing a smaller galaxy. (Swinburne)

Pulsar

When a star collapses on itself a neutron star is left behind. If we were to survive this giant explosion, we would have a new problem of pulsars to deal with. A pulsar is a neutron star that emits rays of electromagnetic radiation. Electromagnetic radiation is rays that vary depending on their frequency and wavelength. Some rays provide us with the visible light we use every day. Other rays below or above the spectra can be very harmful to us. For instance, radio waves (beyond red in the visible spectra) can vibrate the cells in your body heating them up to a deadly temperature while gamma rays (beyond blue in the visible spectra) can stop the function of the cells in your body. Oddly enough, both radio waves and gamma rays are used to treat different ailments.

The Vela Pulsar. NASA pic.

The Vela Pulsar. NASA pic.

New EINSTEIN@HOME effort launched March 25, 2009

Posted by jcconwell in Astronomy, Neutron Stars.
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Einstein@Home, based at the University of Wisconsin–Milwaukee (UWM) and the Albert Einstein Institute (AEI) in Germany, is one of the world’s largest public volunteer distributed computing projects. More than 200,000 people have signed up for the project and donated time on their computers to search gravitational wave data for signals from unknown pulsars.

neutronstar

Help Wanted: Pulsar Hunters

Today, Prof. Bruce Allen, Director of the Einstein@Home project, and Prof. Jim Cordes, of Cornell University and Chair of the Arecibo PALFA Consortium, announced that the Einstein@Home project is beginning to analyze data taken by the PALFA Consortium at the Arecibo Observatory in Puerto Rico. The Arecibo Observatory is the largest single-aperture radio telescope on the planet and is used for studies of pulsars, galaxies, and the Earth’s atmosphere. Using new methods developed at the AEI, Einstein@Home will search Arecibo radio data to find binary systems consisting of the most extreme objects in the universe: a spinning neutron star orbiting another neutron star or a black hole. Current searches of radio data lose sensitivity for orbital periods shorter than about 50 minutes. But the enormous computational capabilities of the Einstein@Home project (equivalent to tens of thousands of computers) make it possible to detect pulsars in binary systems with orbital periods as short as 11 minutes.

“Discovery of a pulsar orbiting a neutron star or black hole, with a sub-hour orbital period, would provide tremendous opportunities to test General Relativity and to estimate how often such binaries merge,” said Cordes. The mergers of such systems are among the rarest and most spectacular events in the universe. They emit bursts of gravitational waves that current detectors might be able to detect, and they are also thought to emit bursts of gamma rays just before the merged stars collapse to form a black hole. Cordes added: “The Einstein@Home computing resources are a perfect complement to the data management systems at the Cornell Center for Advanced Computing and the other PALFA institutions.”

Extreme Universe: Magnetic Fields and Magnetars March 12, 2009

Posted by jcconwell in Astronomy, Extreme Universe, Gamma Ray Bursts, Neutron Stars.
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Neutron Stars are extreme to begin with, but magnetars add a whole new level of extreme to these exotic objects. Magnetars,  as the name implies, are neutron stars with ultra high magnetic fields. As a matter of fact, the most extreme magnetic fields ever found in the universe!

An artist's rendering of a magnetar, a type of neutron star.  (Image Credit: NASA, CXC, M. Weiss)

An artist's rendering of a magnetar, a type of neutron star. (Image Credit: NASA, CXC, M. Weiss)

There are about 15 magnetars known, they are all examples of a class of objects called “soft gamma repeaters” . The most magnetic one, and the most magnetized object in the known universe is SGR 1806-20. The magnetic field of this magnetar is estimated to be about 2 x 1011 Teslas or 2 x 1015 gauss, one Tesla being equal to 10,000 gauss.

Now, to give you some sense of how big this is, the Earth’s magnetic field is about 1/2 gauss or .00005 Tesla.  The magnet in a hospital’s  MRI is about 3.2 Tesla or 32,000 gauss, and the largest sustained magnetic field created in a lab is about 40 Tesla.

So we’re talking about magnetic fields 1000 trillion times bigger than the Earth’s field. Very weird things can happen with fields this large. One thing that’s interesting  is how much energy is stored in such a field. So let’s break out an equation from physics and use an example I did in my electricity  & magnetism  class last week. If you look it up,  you’ll find  the energy per cubic meter, or energy density, of a magnetic field is given by:

u = B2/2 μ0

u is the energy density given in Joules per cubic meter. A Joule is the energy you use to lift a kilogram about 10 centimeters off the ground. 

B is the strength of the magnetic field  given in Teslas, and  μo is a constant that has a value of 4π x 10-7 (it has units , but we’ll ignore them).  Using a field of B = 2 x 1011 Teslas, the most powerful magnetar, we will get a huge number…

1.6 x 1028 Joules/(cubic meter)

or every cubic meter contains this amount of energy. To put this in context, the largest hydrogen bombs have a yield of 20 Megatons of TNT, which is about 1017 Joules of energy. So in each cubic meter of magnetic field has the stored energy of 160,000,000,000 (160 billion), 20 Megaton bombs.

Since we’re having so much fun, lets think about it this way. Einstein showed mass and energy are equivalent, so how much mass would one cubic meter of this HUGE magnetic field have? Well…

E=mc2

or  m = E/ c2 = 1.6 x 1028 Joules/(3 x 108m/s)2 = 1.78 x 1011kilograms

Each cubic centimeter of magnetic field would have a mass of 178 metric tons!!! If you multiply this by the number of cubic meters in the Magnetar, about 40 trillion, assuming the whole neutron star is magnetized, you get a lot of magnetic energy stored in Magnetar.

To give you an idea of what a small amount of this energy would do, consider the events of December 27, 2004. On that day the magnetar we’ve been using as a example, SGR 1806-20, under went a “superflare”. The “superflare,” from a magnetar named SGR 1806–20, irradiated Earth with more total energy than a powerful solar flare. Yet this object is an estimated 50,000 light-years away in Sagittarius.  During that flicker of time it outshone the full Moon by a factor of two. The gamma rays struck the ionosphere and created more ionization which briefly expanded the ionosphere. Assuming that the distance estimate is accurate, the magnetar must have let loose as much energy as the Sun generates in 250,000 years.