|MadSci Network: Physics|
Dear Peter, I'm assuming from your question that you mean the creation of the elements, beginning with hydrogen...."Where will the creation of the elements end and into what will they decay?" As it turns out, all the elements have decay paths. What are known as the "radioactive elements" decay to lighter elements relatively "quickly" (seconds-to-100,000 years). The other elements will also decay, but on longer timescales of 10^33(1 with 33 zeros after it) years and by different physical processes, such as nucleon decay (decay of the protons within the elements) into quarks. See this URL for mor info... => http://hep.bu.edu/~superk/pdk.html Astronomers have studied how elements heavier than iron were produced in the early Milky Way have identified a distinct series of epochs of galaxy- wide chemical formation. Looking at hundreds of stars in the oldest part of the Milky Way – the “halo” region around the center - they have developed a timeline to explain their observations: The Pre-Stellar Epoch The Big Bang jumpstarts the initial large-scale production of hydrogen, deuterium, helium and lithium. The Epoch of Very Massive Stars The earliest stages of heavy element formation in the Galaxy were dominated by stars with masses ten times that of the Sun or more, and lifetimes of a few million years or less. These supermassive stars produced small amounts of all the elements, but their presence can be identified most clearly by excesses of elements like strontium, yttrium and zirconium. Released by supernovae and absorbed by new star-forming clouds, these elements were incorporated into the next generation of stars. The Europium Epoch For the next 30-100 million years, element formation was dominated by supernovae from stars with about 8-10 times the mass of the Sun. These longer-lived stars enriched the Milky Way in heavier elements like barium, europium, and other lanthanide elements in the Periodic Table, such as cerium. The Double Shell Epoch A major shift from previous epochs, lasting from about 100 million to a billion years after the Galaxy formed, it featured stars with perhaps 3-7 times the mass of the Sun. These stars produced more strontium, barium, and some particular lanthanides from nuclear-burning interior shells during the later stages of their evolution, not by supernovae. Their products are characterized by more solar-like distribution of heavy elements. The Iron Epoch From one billion to three billion years after the Galaxy formed, supernovae from white dwarf stars a bit larger than the Sun produced large amounts of iron. The addition of large amounts of iron to the Milky Way's chemical stew can be deduced by the relative decrease of heavier metals within stars which hold about 1/100th of the Sun's overall metal abundance. Since this epoch, which ended roughly 10 billion years ago, the major edition to the Galaxy's inventory of heavy elements has been lithium. This timeline may be a surprise. The evolutionary path taken by stars is not a straight-line creation of lighter-to-heavier elements. In fact, most of the heavier elements in the Milky Way Galaxy were formed 2-3 billions years ago, while today lighter element production seems to dominate. So, to answer your question, the evidence to date seems to indicate that we will not see the creation of any heavier elements than now exist naturally, or are created by humans artificially…unless there is a future epoch in stellar evolution we do not forsee. A useful URL is… => http://calspace.ucsd.edu/virtualmuseum/ita/03_2.shtml Hope this helps answer your question(s)! ---* Dr. Ken Beck
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