--------- #1318 - Kepler’s Supernova
- Attachment: Composite image of supernova
- Johannes Kepler saw his supernova over 400 years ago. It occurred in the Constellation Ophiucus, the Serpent Bearer, just 20,000 lightyears away. Kepler had only his unaided eye to watch the new star that was brighter in the night sky than the planet Jupiter. It lasted for 18 months and is the last observed supernova in the Milky Way Galaxy.
- When the Supernova , SN1604, first exploded, first observed October 9, 1604, Kepler started his observations October 17. It was named after him because he wrote a book about his observations in 1606. The explosion sent a shockwave expanding into the interstellar gas medium around the star. The gas atoms heated to temperatures of millions of degrees. High energy particles created in this heat began emitting X-ray radiation. This X-ray spectrum is what was detected to create the composite image in the picture attached, see last paragraph.
- Astronomers studying the supernova remnants and debris have noted the presence of large amounts of the element iron. They also cannot detect any remnant star located at the core. Large massive-star supernova leave behind a Neutron Star or a Blackhole. Kepler’s Supernova seems to have evaporated everything. Normally this scenario would indicate a Type 1a Supernova. Type 1a supernova are created by a binary system where one star is a White Dwarf under 1.4 Solar Mass. The White Dwarf having greater mass than its companion star accretes gas and material from the other orbiting star. This accretion over time builds up the mass of the White Dwarf until it exceeds 1.4 Solar Mass. When this happens gravity collapses the star to its core creating a thermonuclear explosion we call a supernova.
- In Kepler Supernova’s case a strange phenomena is occurring. The explosion is expanding into a dense material rich in nitrogen. This would suggest a Type II Supernova which occurs in much more massive stars where layers of elements are expelled before the explosion.
- A Type II supernova occurs from a super massive star that sheds its outer layers of the layered elements before the explosion occurs. This counter diction was reversed again when astronomers carefully measured the ratio of oxygen to iron elements. This ratio suggested a Type 1a Supernova. To resolve this astronomers now believe this particular Type 1a supernova somehow came from a more massive star than unusual. Not, necessarily a star that had just reached exactly 1.4 Solar Mass.
- Type 1a supernova are used as “standard candles” of brightness to judge the distances of supernova and the galaxies they live in, or die in. A careful study is needed on this 400 year old explosion to better understand the mechanisms that create this expected luminosity. Astronomers are using these distance measurements to explain the Dark Energy that is expanding the Universe. Astronomers also view Type 1a supernova as the primary source of the amount of iron found in the Cosmos. A better understanding may change some previous “discoveries”.
- The Kepler remnant image uses red to represent the low-energy X-rays. The material around the star is dominated by the element oxygen that has been superheated from the explosion’s shockwave. Yellow is the color representing higher-energy X-rays coming from the element iron. Green is the medium-energy X-rays coming from other elements. Blue represents the highest-energy X-rays at the bow of the shockwave.
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(1) Johannes Kepler (1571-1630) was the son of a professional soldier. His grandfather was the mayor of his hometown. He got a religious education because having smallpox at 3 crippled his hands and weakened his eyes making him unfit for strenuous work. He received a Masters degree in 1591. He was brilliant at math and wound up a teacher of science at U. of Graz, Austria. In those days astronomers were supposed to be astrologers and he found himself giving horoscopes to the emperor and other rich elites. In 1598 he went to work in Prague with Tycho Brahe. When Tycho died in 1601 Kepler inherited all of his astronomical observation data. He really began studying the data more carefully when he witnessed “Kepler’s Supernova” on September 30, 1604. Kepler tried to fit Tycho’s data using Greek musical spheres and Plato’s five Platonic solids. After years of effort he finally discovered the ellipse that could exactly fit Tycho’s data. When the ellipse was used on Mar’s orbital data he found the Sun to be one focus of the ellipse. In 1609 he published his first book announcing, “ a line connecting the planet and the Sun will sweep over equal areas in equal times as the planet moves about its orbit“.
- Kepler’s ellipses put an end to Greek astronomy using celestial spheres. It remained for Isaac Newton to explain gravity and why the Sun controlled the orbits of the planets. In 1619 Kepler’s second book announced, “ the square of the period of revolution of a planet is proportional to the cube of its distance from the Sun.” Kepler wrote to Galileo about these theories and Galelio sent Kepler one of his first telescopes. Kepler continued his studies making improvements in the optics of telescopes. He used Napier’s logarithms in his calculations. He predicted the transit of Mercury across the face of the Sun that occurred in 1631. Kepler had 13 children and still found time to write a story, “Somnium” about a man who traveled to the moon. His manuscripts are preserved in the Pulkovo Observatory in Russia.
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