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- Stars form from a gigantic cloud of intergalactic gas and dust. It has to be very large in order to have the gravity needed to collapse and create the pressure needed to form stars. This is never a smooth occurrence. Many disturbances and shockwaves end up producing multiple stars from the collapsing cloud. Astronomers expect that when our Sun first formed 4.6 billion years ago it formed with a cluster of a thousand other stars. Where are these stars today?
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- Our nearest star is 4.3 lightyears away. In 4.6 billion years the other stars should still be within 300 lightyears of us. They would have nearly the exact chemical composition as our Sun. Can we find them? We should be able to identify them once we do.
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- How do we know that our Sun formed 4,600,000,000 years ago?
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- Meteorites from the Solar System’s early years contain decay products, isotopes of nickel-60 and iron-60. Some have been dated to be 2,600,000 years old., relatively young. These isotopes had to be created in supernovae explosions. These supernovae were likely within 0.07 lightyears distance at the time.
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- The Sun’s present isolation and location in the Milky Way is half way out from the galaxy center, a radius of 26,000 lightyears. Our Solar System has been orbiting the Galaxy at 124 miles per second, 446,400 miles per hour. Since the Sun was born it has made 27 orbits about the center of the Galaxy.
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- In 1960 star clusters were first discovered in the Milky Way. The thousands of stars were so dense they were at first mistaken for a single star.
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- If the Sun did start in such a cluster of stars and if they numbered 3,500 within a diameter of 10 lightyears, then some 50 similar stars should still be located with 300 lightyears of our Sun’s orbit. Astronomers are trying to find one of these stars that have the same chemical makeup as our Sun.
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- We know that the Sun and the Solar System were born close to the other stars because the Sun and the Earth are composed of heavy elements that could only be created in supernovae explosions of other stars.
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- A cloud of gas starts out at 1,000,000 Solar Mass and stars to collapse due to gravity. When the gas and dust becomes most heavily concentrated one or more massive stars form. Often spinning binary stars form.
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- When a star forms it emit’s a shockwave of ultraviolet radiation for the first time. The expanding radiation ionizes the surrounding gas in the front of the shockwave. When the shockwave reaches concentrations of gas in the cloud it causes new stars to from, like our Sun.
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- When the ionization wave hits anew born sun the surplus gas is boiled off. the proto planetary disc is exposed to direct ultraviolet radiation. After 2,000,000 the more massive stars explode. The more massive the star the shorter its lifetime. The material in the explosion is included in the planetary forming systems, in the accretion disks of solar systems.
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- After the most massive stars explode in the cluster gravity is reduced and the smaller stars begin to drift apart. The stars that were born in the same cluster as the Sun move away from each other at a few miles per second. Today, after 4,000,000,000 years and 27 orbits around the Milky Way these stars are tens of thousands of lightyears apart.
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- Although they may be up to 1,000 lightyears away these stars should still be following the same path around the Milky way. Also, they should have the same composition of element as the Sun. Astronomers are confident they will be able to find some of these star that were born with our Sun. Our Sun’s way off brothers and sisters may have planets just like ours. ( See Review #1456 “ Our First Alien Encounter” ) An announcement will be made shortly, stay tuned.
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707-536-3272, Saturday, April 7, 2012
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