- 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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- There are 100 billion galaxies, with 100 billion stars each. That is 10^22 stars that represent all the lifetimes of stars. That is more stars that all the grains of sand on the beaches of the planet Earth.
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- These are the same stars that have created the calcium in your bones, the iron in your blood, the potassium in your nerves. The iron in your blood could contain atoms that are 8 billion years old. When the cores of stars create fusion up to iron and nickel they stop radiating pressure against gravity. These two are the heaviest elements that are created with an excess of energy after fusion. Heavier elements are still created by immense gravity pressure by their fusion absorbs energy rather than releasing it. Therefore, the star continues to collapse into its core creating the 87 heavy elements.
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- When massive stars collapse to their core the collapse rebounds into a massive explosion. A supernova. The heavy elements that were created get spread out across the cosmos. These elements become the interstellar medium that in turn creates the next generation stars. What is left behind at the core is a neutron star or a Blackhole.
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- Supernovae explosions are so bright they have been seen by astronomers that are 12 billion lightyears away. The only brighter explosion is called a Gamma Ray Burst that pointing directly at us is 13 billion lightyears away. That is from a Blackhole that is exists only 700 million years after the Big Bang.
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- On March 19, 2008, 11:13 Pacific Time, looking at the Constellation Bootes you could have seen a Gamma Ray Burst with the naked eye. It was a Burst of X-rays and Gamma Rays but also visible light rays of magnitude 5.3. The bright light lasted for 50 seconds before diminishing. GRB080319B was 7.5 billion lightyears away. It was the farthest thing a human eye has ever seen. The polar jet of the Burst was aimed directly at us. The Blackhole the created the Burst was born over 2 billion years before our Sun was born.
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- 15 times supernovae have been observed before the exploded thanks to archived records of the sky. Novae are less bright than supernovae and occur when a smaller star transfers matter into a White Dwarf star that are in a binary system. RS Ophiuchi is a binary system that goes Nova every 20 years.
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- Using spectrographs to detect the elements in a supernova explosion have defined two types of supernovae:
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--------------- Type I Supernovae have little evidence of hydrogen
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--------------- Type II Supernovae have an abundance of hydrogen in their explosion.
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- There are 3 sources of energy in the rapidly expanding gas of a supernovae:
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------------------ (1) Radioactive decay of freshly synthesized elements, such as
Nickel-56.
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------------------- (2) The expanding shockwave heating the stars hydrogen atmosphere.
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------------------ (3) The interaction between the ejecta and the hydrogen gas.
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- There are sub categories of Types I and II supernovae: Type Ia is the brightest due to its abundance of radioactive elements. The explosion involves the total destruction of the White Dwarf Star.
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- Our Sun is not massive enough to become a supernova. When it exhausts its hydrogen fuel in 10 billion years it will fuse helium into carbon and oxygen and then stop. There is no more mass left to provide the gravity to continue the fusion process.
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- More massive stars do not end their fusion process, carbon and oxygen fuse into neon , silicon, iron-nickel. Once a star sues iron further fusion absorbs energy rather than releasing energy. The star collapses to the core and rebounds into a supernova explosion.
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- Gamma Ray Bursts occur about once a day in the Observable Universe. These are flashes of energy peaking in the Gamma-Ray part of the electromagnetic spectrum. Short Bursts lasting a few seconds are created when Neutron Stars merge. Long Bursts lasting minutes are the mergers into Blackholes. The Gamma -Ray Burst that was detected September 16, 2008, was 12.2 lightyears away. Gamma Rays are particles not rays, though the misnomer has stuck, were traveling 99.9999 percent the speed of light.
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- Here is how the different supernovae are identified by their light spectrum:
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---------------------------------- Hydrogen -------- Helium --------- Silicon -----------
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-------------- Type I ------------- No ------------- No --------------- No -----------
-------------- Type Ia ------------ No ------------- No --------------- Yes -----------
-------------- Type Ib ------------ No ------------- Yes -------------- No -----------
-------------- Type Ic ------------ No ------------- No --------------- No -----------
-------------- Type II ------------ Yes ------------- No --------------- No -----------
-------------- Type IIb ----------- Yes ------------ Yes -------------- No -----------
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- The supernovae debris from these explosions ends up in an interstellar dark cloud that condenses further into nebulae like the Orion Nebula that are star factories of the next generation stars. The density of the Orion Nebula is only equivalent to 150,000,000 hydrogen atoms per cubic meter. We are living in one of the densest parts of the Universe when measure the density of gases and the interstellar medium. The Earth atmosphere contains the equivalent of 7.5*10^26 hydrogen atoms per cubic meter.
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------------------------- Density = Mass / Volume
------------------------ Mass of Earth’s atmosphere = 5.1*10^18 kilograms
------------------------ Volume of Earth’s atmosphere = 4.2*10^18 meters^3
----------------------- Density = 1.21 kg / m^3
---------------------- Hydrogen atom = 1.6*10^-27 kilograms
---------------------- Density of Earth’s atmosphere = 0.76*10^27 H/m^3
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- Comparing densities across the gaseous cosmos:
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---------------------- Density of Earth’s atmosphere ==== 0.76*10^27 H/m^3
---------------------- Red Supergiant Betelgeuse ========= 1.1*10^25
---------------------- Surface of the Sun =============== 1.3*10^23
---------------------- Atmosphere of the Moon =========== 3.3*10^15
---------------------- Solar Corona =================== 6.2*10^13
---------------------- Interstellar Dark Cloud ============ 1.2*10^11
---------------------- Orion Nebula =================== 1.5*10^8
---------------------- Solar Wind inside Earth orbit ======= 20,000,000
---------------------- Milky Way Galaxy =============== 81,000
---------------------- Van Allen Radiation Belts =========== 53
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- We are living in and made of star dust and gas. When you look at the night sky and see those stars say “ that is where I came from”. We have watched the wobble of these stars in our Galaxy and found 1,115 other planets to date. There are many more. Is there anyone anywhere else saying the same thing, “ that is where I came from”. An announcement will be made shortly, stay tuned.
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