- 3159 - SUPERNOVA - why do stars explode? Astronomers have problems explaining how the supernova explosion actually occurs. A theory is that the explosion happens because of sound waves? That is what computer simulations are telling astronomers today. All the math remains to be worked out, but, computer simulations are getting closer to the observations they see in supernova explosions.
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- How Do Stars Form to Begin With? Astronomers can tell you the simplest concepts for star formation. But, the cosmos is not simple. Things are much more complicated than that and astronomers are still trying to explain the details and gaps in their theories.
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- Stars are born from a cloud of gas and dust. Gravity will naturally increase the density of the core of the cloud. Gas pressure pushes against the compression pressure of gravity but when the density collects enough mass the gravity overcomes this pressure causing the collapse of the star into its core.
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- When the core becomes dense enough and hot enough it sparks nuclear fusion of hydrogen into helium. The heat and radiation generated by the fusion reaction increases the pressure outward to halt further collapse.
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- A dynamic equilibrium settles in between fusion’s outward pressure and gravity’s inward pressure. The balance can last for millions, even billions, of years until the hydrogen fuel is all consumed. The above paragraphs is the simple concept. Now, let’s get into some of the complications.
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- We started with a molecular cloud of gas. But, where did the molecular gas come from in the first place? Gas clouds can not just pop out of space. And, if the gas is spread throughout the interstellar medium how does it begin to form into concentrated clouds?
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- Next, we have a giant cloud of gas. What makes it start to collapse. We can understand that once it starts to collapse towards a center why it would continue to collapse. But, if gas is evenly dispersed throughout the cloud, gravity pulls in all directions. What creates a “center’ and starts gravity pulling in that direction?
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- Our simple theory had one star. But, single stars do not usually form by themselves. Massive gas clouds from multiple embryo stars all interacting inside the same cloud. If we have a crowded nursery of stars things cannot behave that simply.
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- If a star forms that is over 20 Solar Mass than this concept of star formation does not even compute. The nuclear fusion of such large stars would blow the star apart before gravity could compress it further. The stellar winds and supersonic shockwaves should prevent stars larger than 20 Solar Mass from even forming. However, we do know that these massive stars somehow form.
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- New stars seem to consist of nearly 75% hydrogen and nearly 25% helium and less than 1% of the heavier elements.
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- When gas clouds first exist they are so diffuse as to contain one hydrogen atom per cubic centimeter. But, as the cloud cools by radiating heat, infrared radiation, the radiation is 158,000 nanometers in the far infrared. The cloud becomes denser as it cools.
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- When it reaches 1000 atoms / cm^3 the atoms block ultraviolet radiation that has been emitted from other stars. Clouds that reach a density of 10,000 atoms / cm^3 become opaque to even the thermal infrared wavelengths.
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- When this happens astronomers cannot see what is going on inside the star formation. The cloud starts out some 3 times more massive than the stars. Somehow the rest of the mass is lost in space.
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- These mysteries have not even introduced the influence of rotation on star formation. Or, the influence of magnetic fields once ionized particles are in motion. We also need to add the chaos introduced by shockwaves from nearby supernovae. Stars can not form uniformly. That would just be too simple.
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- Why do stars explode when they die? We know that stars die when they run out of fuel for supporting their nuclear reactions. But, why don’t they just fade away in to the sunset?
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- Stars under 8 Solar Mass will explode slowly into a Planetary Nebulae. Stars greater than 8 Solar Mass will explode instantly into a Supernovae. What causes an explosion when they run out of fuel? How big is a Supernova explosion?
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- A single massive star in a supernova explosion can release in an instant as much power as all the visible light in the entire Universe. How is this possible? What can create so much power?
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- The result of this power actually manufacturers all of the 114 heavier elements in the Periodic Table above hydrogen and helium. After spreading all of these elements in an explosion into interstellar space the remnant left behind is either a Neutron Star or a Blackhole, depending on how much mass stays behind.
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- Astronomers have problems explaining how the explosion actually occurs. However, a going theory is that the explosion happens because of sound waves? That is what computer simulations are telling astronomers today. All the math remains to be worked out, but, computer simulations are getting closer to the observations they see in supernova explosions.
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- We start out with a star that has greater than 8 times the mass of our Sun. Stars this big burn through their hydrogen in 10,000,000 years. After the hydrogen is gone the immense pressure of gravity and the extreme temperatures at the core begin to burn the helium, fusing it into carbon.
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- The helium fuel is exhausted in another 2,000,000 years. Next, the carbon begins a fusion reaction into neon. But, this lasts only 2,000 years.
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- The star’s core is running through its fuel in succession hydrogen, helium, carbon , neon, oxygen, silicon, up to iron. When the core fuses silicon it lasts only 3 weeks. It quickly gets to iron-nickel at the core.
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- The core then is 1.5 Solar Mass and only the size of the Earth. Iron does not fuse into a heavier element. Fusing iron consumes energy rather that releasing energy. All fusion instantly stops. Nothing is left to stop the compression of gravity.
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- 32 milliseconds before the collapse of the iron core the electrons merge with the protons to form neutrons. Neutrinos stream from the core as neutrons are being created. The iron core collapses at ¼ light speed.
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- The core collapses into a neutron core 78 miles in diameter then rebounds outward with an enormous shockwave. The in falling gas and rebounding shockwave collide creating an oscillation wave of 300 cycles per second, a 300 hertz “sound wave“.
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- The 300 hertz sound wave creates an asymmetry in the in falling material. The shockwave breaks through and the supernova explosion begins 979 milliseconds after the core has collapsed into neutrons.
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- This chaos created in every supernovae explosion means that no two supernova explosions occur exactly alike. Besides the shockwaves and sound waves there are other affects that need to be included in the computer simulations. The effects of centripetal forces due to rotation, the magnetic fields due to ionized particles in motion, the effects of streams of neutrinos escaping the core, and more.
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- Once this all comes together the nuclear flames expand through the star exceeding 10,000,0000,000 degrees Kelvin. The flame breeches the surface of the star at 6,700,000 miles per hour. The flagration rips the star apart sending material into outer space leaving behind a Neutron Star or a Blackhole.
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- The power released is greater than all the light in the Universe. The power released covers the entire electromagnetic spectrum into the highest Gamma Rays of energy.
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- The two most likely Supernovae to explode in our neighborhood are Betelgeuse and Eta Carinae. Let us hope astronomers can figure this all out before one happens in our neighborhood.------------------------------------------- Other reviews available:
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- 3013 - SUPERNOVA - one explosion nearby? At that same time, there was also an extinction event on Earth, called the “Pliocene marine mega fauna” extinction. Up to a third of the large marine species on Earth were wiped out at the time, most of them living in shallow coastal waters.
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- 2997 - SUPERNOVA - gold forged in exploding stars? - Astronomers are winding back the clock on the expanding remains of a nearby, exploded star. By using our Hubble Space Telescope, they retraced the speedy shrapnel from the blast to calculate a more accurate estimate of the location and time of the exploding star.
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- 2650 - SUPERNOVAE - are what we are made of! - Supernovae, stars that explode when they can no longer continue fusion radiation, are rare events. They are likely to happen only once per year in our Milky Way Galaxy. But, in the Observable Universe the event happens every second.
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- 2649 - SUPERNOVA - the runaway universe? Nuclear fusion will occur when a star’s central temperature reaches 10,000,000 degrees. The collisions of the atoms are so rapid at that temperature that all electrons are stripped away from their nucleus. And, nuclei collide to such an extent as to overcome the repulsive electric force of their mutual positive charges.
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- 2648 - SUPERNOVA - what is the youngest? A supernova normally goes off in a galaxy every 50 to 100 years. However, we have not seen one in several hundred years. It could be that they are going off and they are out of sight. The last one astronomers had recorded for the Milky Way is Cassiopeia A. It went supernova 330 years ago, that would be in 1678.
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- 2646 - SUPERNOVAE - how life is being created? Betelgeuse is still deep in the red supergiant phase of its life. Even though it has dimmed significantly of recent, it isn’t on the verge of exploding. The gradual dimming and brightening we see suggest that it won’t be exploding in our lifetimes. It suggests that the core of Betelgeuse is still chugging away at a steady pace.
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- 2636 - SUPERNOVA - 2 explosions being studied? Astronomers have detected the fallout of the biggest known explosion in the universe since it was born more than 13 billion years ago. The blast came from a supermassive black hole in the Ophiuchus galaxy cluster, located nearly 400 million light years from Earth.
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- 613 - From supernova to our Sun.Nuclear fusion will occur when a star’s central temperature reaches 10,000,000 degrees. The collisions are so rapid at that temperature that all electrons are stripped away from their nucleus. And, nuclei collide to such an extent as to overcome the repulsive electric force of their mutual positive charges. The Strong force acts over a distance of only .0000000000001 centimeters (10^-13), the width of an atom, but, it completely overpowers the electromagnetic force and the nuclei fuse together. When two protons fuse they form the nucleus of deuterium, but the mass is about 1% less than the combined mass of the two protons. This amount of mass is converted into energy according to E = mc^2 and in the form of a positron (a positive or anti-electron) and an anti-neutrino.
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- 831 - Supernova 1987A. We first saw Supernova 1987A in the Large Magellanic Cloud over 20 years ago. That is the astronomers in the southern hemisphere saw it with the naked eye, beginning February 23, 1987. It is below the southern horizon for us. The Large and Small Magellan Clouds look like glowing clouds but both are irregular galaxies. Maybe they are part of our Local Group of galaxies, but recent evidence is that they are just passing by. The Large Magellan Cloud is 1/20th the size of the Milky Way Galaxy and has 1/10th as many stars. One of these stars blew up and 20 years later it is still giving astronomers new information about supernovae.
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- 929 - The youngest supernova. A supernova normally goes off in a galaxy every 50 to 100 years. However, we have not seen one in several hundred years. It could be that they are going off and they are out of sight. The last one astronomers had recorded for the Milky Way is Cassiopeia A. It went supernova 330 years ago, that would be in 1678. Today the remnant of that explosion has an expanding shockwave that is 10 lightyears in diameter. The shockwave has an average velocity of 20,300,000 miles per hour
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- 984 - The art of astronomy.Today you are seeing many amazing images of astronomical objects in newspapers, magazines, and TV. These images are called “false color images” and they are coming from new types of cameras in space and around the world. They are the new “art of astronomy
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- 1308 - Supernova Tycho Brahe of 1572
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- 1319 - RCW-86 Supernova is one of about 8 supernovae explosions witnessed by the naked eye in recorded history. The Chinese recorded this one in the year 185 A.D. They called it the “Guest Star” and it remained in the night sky for 8 months.
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- 1320 - When Supernova Sn1006 first explode in the year 1006 it was brighter than the planet Venus in the night sky. It was even visible during the day for several weeks after the explosion even though it was 7,000 lightyears away.
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- 1411 - The brightness also depends on the proportion of metals in the star. Space is full of explosions and we are just getting the technology that allows us to begin seeing them. This picture is of a supernova remnant is the debris left after a star exploded some 400 years ago. After much study it was decided that this is a beautiful example of two White Dwarf stars in a binary system that went supernova. One exploded obliterating the other. It is called a type 1a supernova when one star steals mass from another and reaches that 1.4 Solar Mass threshold that collapses atoms into the nuclei. The rebound is a supernova explosion.
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- 1566 - Supernovae are what we are made of. Gamma Ray bursts occur about once a day in the Observable Universe. When Supernova Sn1006 first explode in the year 1006 it was brighter than the planet Venus in the night sky. It was even visible during the day for several weeks after the explosion even though it was 7,000 lightyears away.
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- 1684 - What does a supernova explosion sound like? In space there is no sound. However, technology can detect electromagnetic radiation and translate it to the frequencies we can hear. What can we learn from this?
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- 1698 - How rare are we in the Universe? We are made of elements created in exploding stars. Our world has such abundance but how rare is this abundance in the Universe? For every 1 million miles of space galaxies are receding each other by 47,000 miles per hour.
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- 1699 - Betelgeuse is 640 lightyears away. It is a 20 Solar Mass Red Supergiant star that could go supernova tomorrow.
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- 1881 - Supernovae are like snowflakes. No two are alike. Yet, we try to use a special type of supernovae explosion as a “standard candle“, a known brightness that can be used to calculate distance. However, supernovae, in general, can be 100 times brighter and 100 times dimmer than the average supernovae explosion.
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- 2299 - You are made of stardust. A Supernova is a sun, a star, that explodes because it becomes unstable after it exhaust all of its nuclear fuel. Our Sun will not become a Supernovae because it is not big enough. A bigger star will have the gravity necessary to overcome the electromagnetic force between the electron and nucleus of atoms and when its fuel is gone it goes supernova.
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- 2300 - Supernovae you can see. If you have read 2299 - “ You Were Made from Star Dust - Supernova”, you are probably anxious to learn more about Supernova. It turns out that in the last 1000 years at least six, maybe eight supernova explosions have been seen by naked eye observers.
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- 2345 - Scientists estimate it takes 100,000,000 to 200,000,000 years for intelligent life to emerge and colonize a planet. 65,000,000 years ago, at the end of the Cretaceous-Tertiary (K-T) period, 50% of life on Earth was extinguished. The dinosaurs did not survive. But, some half of marine invertebrates, plankton, marine reptiles did survive. 65,000,000 years later here we are and you are reading about it.
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- 2426 - LIFE - Exploding stars create life , and destroy life. Our galaxy is big and mostly empty space, but it harbors millions of blackholes that are remnants of supernovas and collapsing stars. When a giant star burns all it’s fuel, no heat remains to create the pressure withstanding the compression of gravity. The force of gravity collapses the stars mass into a singularity at the center of a blackhole. These creators of life are every where.
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- May 15, 2021 SUPERNOVA - why do stars explode? 1134 1135 3154
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