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----------------------------- 1932 - Supernova 1987
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- Where were you in 1987? Ok, you may remember this “ A blue super giant supernova lit up the southern sky” Here we are 30 years later and we are still learning, “ what just happened?”
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- Supernova 1987A is 160,000 lightyears away. Happy it was not any closer. It was actually in another galaxy not the Milky Way. It was a smaller galaxy called the “ Large Magellanic Cloud”.
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- In our milky Way Galaxy it is expected to have a supernova explosion every 100 years, on average. This supernova occurred, became visible, February 23, 1987, and some astronomers just happened to be watching.
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- They determined that the star that exploded used to be Sanduleak -69*202, a blue super giant several Solar Mass in size. When the elements fused up to the heaviest element, iron, the fusion stopped. The core collapsed. The outer layers imploded into the core. The core condensed into the density of an atomic nucleus, a neutron. The collapse rebounded sending a shock wave that blew away, exploded, blew up the outer surface. The core left behind became a super dense Neutron Star only 12 miles in diameter.
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- The shockwave continued outward traveling at 10% the speed of light, 18,600 miles per second. The explosion created even heavier elements in the immense heat and pressure. These elements were radioactive. As the radioactivity decayed the energy released continued to heat up the interstellar gas that surrounded the star.
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- The half-life of radioactive elements only powered the explosion for 3 years. In 1990 the gas cooled and dimmed.
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- Seven years later the expanding shockwave encountered another ring of interstellar gas that had been thrown off 20,000 years earlier. This second collision heated knots of material that started glowing like a necklace of pearls. The hot gas was glowing at
1 million degrees Kelvin.
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- A supernova explosion releases an immense amount of energy. The millions of degrees temperature creates X-ray emissions along the shockwave. Meanwhile the core has cooled back to 20 to 100 Kelvin. That is cold, water freezes at 273 Kelvin on Earth.
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- The dust near the core is like smoke, molecules the size up to 0.1 millimeter at 20 degrees Kelvin.
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- The atoms in the dust are many different elements fused in the process. Each element emits specific colors, or wavelengths of light. Emissions are occurring as the electrons in the outer shells of atoms collapse, or jump, to a lower energy level, or shell. Each element atom has a unique set of electron shells so each emit’s a different set of wavelengths, called spectroscopy.
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- Astronomers are recreating a 3-D map of the distribution of each of these elements: hydrogen, iron, silicon, calcium, magnesium, and oxygen.
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- To date astronomers have not been able to create a computer model that replicates a supernova explosion. The hope is that this new data will help create a new mathematical model. Stay tuned, an announcement will be made shortly.
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- Note (1): Request any of the Reviews by number to learn more.
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- #1881 Supernovae are like snowflakes, no two are alike. This review list 9 other reviews available on the subject.
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----- 707-536-3272 ---------------- Monday, February 13, 2017 -----
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