- 2994 - NEUTRON STAR - amazing math and physics? -Neutron Stars are amazing objects for astronomers to study. The Crab Nebula is powered by a neutron star. Ordinary Matter should be called Ordinary Space. The matter part is almost negligible. 99.999,999,999,999,9 % of solid matter is empty space. It is not solid at all. What makes it feel solid is the electromagnetic force.
-------------------- 2994 - NEUTRON STAR - amazing math and physics?
- Because all Ordinary Matter is made of atoms, Atoms are clouds of electrons orbiting around a tiny nucleus composed of protons and neutrons. It is the electromagnetic force that keeps them separated and that force is what you feel.
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- The diameter of the nucleus is 1 / 100,000th the size of the electron cloud. It is the cloud that defines the size of the atom. The electron itself is 1 / 1860th the size of a single proton. An atom is a small nucleus and an even smaller electron and all the rest is empty space.
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- When you sit down in your chair it is that whirling electron cloud traveling at a fraction of the speed of light that is holding you up. The Ordinary Matter that is in the chair is invisibly small.
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- If it were squeezed down to be one kernel of matter it would be the size of a bunch of atomic nuclei. The kernel would still weigh the same as chair. The mass would be the same, but, that would be nearly nothing and the rest would be space.
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- Now put this scenario on the scale of a massive star. A star of 10 Solar Mass would be squeezed down to a Neutron Star about 12 miles in diameter. The gravity of the massive star that runs out of nuclear fuel has no opposing force.
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- The electromagnetic force that holds the electrons in orbit collapses into a single, giant atomic nucleus composed of neutrons. The mass is still the same but it has been squeezed into a ball 12 miles in diameter. The rest of the massive star was empty space.
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- Being only 12 miles in diameter you would be tempted to get close to the Neutron Star. That would be a mistake. The magnetic fields around the star are extremely strong. All the atoms in your body would be distorted to cigar-shaped. A lethal situation.
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- It is not only the intense gravity and the intense magnetic field that you have to avoid. The rotating magnetic field also produces an electric field with potential of a quadrillion volts. There would be a blizzard of high-energy charged particles like lightning bolts only 30,000,000 times stronger.
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- Let’s back away from this Neutron Star. We still get the radiation of X-rays and Gamma Rays. The high-energy particles produce beams of energy emitting everything in the electromagnetic spectrum from radio waves through Gamma Rays.
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- If the beam happens to be pointing at us we detect a pulse of this radiation. If the rotation of the beam is off center the beam will flash by us like a lighthouse. We detect a pulse every complete rotation. Some high school students discovered one of these Pulsars that was rotating 324 times per second. ( 19,000 rpm). ( See Review # 1396 for details.)
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- Astronomers have discovered over 1,000 of these Pulsars. The most famous Pulsar is at the center of the Crab Nebula. The Crab pulses cover the entire spectrum of wavelengths. Only 24 of these Pulsars are detected in X-rays. And, only 6 of these are detected in Gamma Rays.
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- Some of the Pulsars produce extreme magnetic fields. Some magnetic forces are so strong they cause “Star quakes” on the surface of the Neutron Star. When the surface cracks powerful bursts of X-rays are produced. If the star quake is strong enough these flashes can be in Gamma Rays.
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- Sometimes a Neutron Star is close in orbit to a companion star in a binary system. The intense gravity of the Neutron Star can pull gas and material from the companion star. This in falling material spirals into the Neutron Star creating an accretion disk that accelerates around the star, Enormous energies are created in the acceleration of this material and it radiates powerful X-rays.
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- When the rotating material enters the rotational poles it gets ejected in a concentrated beam of material that is hurled into interstellar space. When this beam strikes material in the interstellar medium it generates more X-ray radiation. Between Accretion-powered Pulsars and Rotation-powered Pulsars the accretion powered is more powerful as long as an abundant flow of gas is coming from the companion star.
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- How do you know the accretion-powered Pulsar is a Neutron Star and not a Blackhole?
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- Blackholes do not have a normal solid surface or a normal rotating magnetic field. The X-rays from Blackholes flicker. Those from a Neutron Star produce a steady rate of X-ray pulses.
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- Using your telescope you take an photograph image of
- The width of this image is about 5 light years. If the elliptical ring near the center is actually a circular ring seen at a tilted angle, what is the radius of this ring in:
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- A) light years?
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- B) kilometers? (Note: 1 light year = 5.9 trillion kilometers).
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- The scale of this image can be found using a millimeter ruler. When printed, the image is about 70 mm. The scale is then 5 lightyear / 70mm = 0.071 ly/mm. The radius of the ring will be the maximum radius of the elliptical ring, which you can see by drawing a circle on a piece of paper and tilting it so it looks like an ellipse. On the image, the length of the major axis of the ellipse is 10 mm, so the radius of the circle is 5 mm.
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- A) Using the scale of the image we get 5 mm x 0.071 ly/mm = 0.36 light years.
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- B) The radius in kilometers is just 0.36 ly x 5.9 trillion km/1 ly = 2.1 trillion km.
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- The high-energy particles that make-up the ring were created near the neutron star at the center of the ring. If they are traveling at a speed of 95% the speed of light, to the nearest day, how many days did it take for the particles to reach the edge of the ring? (Speed of light = 300,000 km/s)
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- Time = distance/speed, so for s = 0.95x300,000 km/s = 285,000 km/s, and d = 2.1 trillion km, we get T = 2,100,000,000,000 / 285,000 = 7,368,421 seconds. Converting to days: 7,368,421 seconds x (1 hour/3600 sec) x (1 day/24 hours) = 85.28 days. To the nearest day, this is 85 days.
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- Suppose the pulsar ejected the particles and was visible to astronomers on Earth as a burst of light from the central neutron star 'dot'. If the astronomers wanted to see the high-energy particles from this ejection reach the ring and change its shape, how long would they have to wait for the ring to change after seeing the burst of light?
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- They would have to wait 85 days after seeing the burst of light because light travels faster than the matter in the particles.
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- Another way to appreciate how much faster light travels, calculate the number of days it would take for the pulse of light to reach the ring, compared to the 85 days taken by the particles.
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- The light pulse would take 2.1 trillion km/300,000 km/s = 7 million seconds or about 81 days. So astronomers would have to wait 81 days to see whether the light pulse affects the ring, and then another 4 days for the particles to arrive.
--------------------------- To learn more about Neutron Stars see these reviews:
- 1334 “ Unusual Light from the Crab Nebula?” On July 3, 1054 our time it was a star. One day later, on July 4,1054 it was a supernova that became as bright as the planet Venus in the night sky. It was so bright it could even be seen during the day for several weeks.
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- Ever since this supernova explosion occurred the gas and material have been expanding outwards at 1,000 miles per second ( 360,000 miles per hour). Today we see it as the Crab Nebula occupying the left horn of Taurus the Bull.
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- 1261 “ What is Making the Crab Nebula So Active?” The Crab Nebula is supernova remnant located in the Constellation “ Taurus the Bull”. It was first discovered July 4, 1054. It has been an expanding ball of gas and debris for the last 957 years.
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- Today the bubble is 4.4 lightyears across. New satellite telescopes have been observing the Crab in the X-ray and Gamma Ray wavelengths. Astronomers were surprised that the Crab is still very active. So active they do not have the physics to explain it. There is always more to learn
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- 1100 - What Created the Crab in Taurus? The Crab Nebula, (M1) in the Constellation Taurus the Bull is the result of a supernova explosion of a massive star that occurred July 4, 1054. Taurus is a “V” shaped constellation with Aldebaran being the brightest near the point and Zeta Taurus and Beta Taurus being the top point of the “V”. Pleiades, the Seven Sisters, (M45) , the sky’s brightest open cluster of stars, lies just to the west of Taurus. Next to the star Zeta Taurus is the Crab Nebula.
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- 862 - Crab Nebula Neutron Star. There are over 1000 Pulsars that astronomers have identified. Probably the most studied of these is the Crab Nebula which was a supernova that exploded in 1054. It is 6,000 lightyears away in the Constellation Taurus the Bull. It is 4.4 lightyears across having expanded for 953 years. ( July 4, 1054 supernova recorded in Chinese history).
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- The total luminosity of the nebula is 5*10^31 watts, compared to the luminosity of the Sun at 3.8*10^26 watts, it is 100,000 times brighter. It contains a remnant star at its core that is a Pulsar with a period of 33.085 milliseconds. That means the star is rotating 30 revolutions per second.
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- The period of rotation is so accurate that it represents one of the most accurate clocks in the Universe In fact, our system of atomic clocks on Earth use several of these pulsars to synchronize the clocks around the globe to the correct time
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- 720 - In 1758 at the age of 28, Charles Messier finally decided that he would publish a catalog of these fuzzy objects that were not comets so fellow astronomers would not waste their time. The first nebula in his catalog was M1, later to be known as the Crab Nebula. His first catalog published with 45 objects.
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- In 1780 a second edition had 68 objects. Today his catalog is still used cataloging 110 beautiful nebulae, galaxies, star clusters, and supernovae remnants, and no comets. He discovered 21 comets in his lifetime. He was the first to spot Halley’s comet when it returned on its 76 year orbit in 1758. The Crab Nebula is in the Constellation Taurus the Bull. The end of the southern horn of the bull is the star, Zeta. Next to Zeta is the Crab Nebula.
January 22, 2021 NEUTRON STAR - math and physics? 1397 2994
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