Starship Asterisk*

tnzkka wrote:AFAIK element 43 Tc (Technetium) is also manmade, hence it's name.
At least the Dutch Wikipedia agrees with me.
Any comment or rectification on my knowledge or on Wikipedia(Dutch)?

heehaw wrote:
I thought Li, Be, B were, with He, made in the first 3 minutes?

https://en.wikipedia.org/wiki/Beryllium wrote:
<<Both stable and unstable isotopes of beryllium are created in stars, but the radioisotopes do not last long. It is believed that most of the stable beryllium in the universe was originally created in the interstellar medium when cosmic rays induced fission in heavier elements found in interstellar gas and dust. Primordial beryllium contains only one stable isotope, ⁹Be, and therefore beryllium is a monoisotopic element.

[b][color=#0000FF]Plot showing variations in solar activity, including variation in sunspot number (red) and [sup]10[/sup]Be concentration (blue). Note that the beryllium scale is inverted, so increases on this scale indicate lower [sup]10[/sup]Be levels[/color][/b]

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Radioactive cosmogenic ¹⁰Be is produced in the atmosphere of the Earth by the cosmic ray spallation of oxygen. ¹⁰Be accumulates at the soil surface, where its relatively long half-life (1.36 million years) permits a long residence time before decaying to boron-10. Thus, ¹⁰Be and its daughter products are used to examine natural soil erosion, soil formation and the development of lateritic soils, and as a proxy for measurement of the variations in solar activity and the age of ice cores. The production of ¹⁰Be is inversely proportional to solar activity, because increased solar wind during periods of high solar activity decreases the flux of galactic cosmic rays that reach the Earth. Nuclear explosions also form ¹⁰Be by the reaction of fast neutrons with ¹³C in the carbon dioxide in air. This is one of the indicators of past activity at nuclear weapon test sites. The isotope ⁷Be (half-life 53 days) is also cosmogenic, and shows an atmospheric abundance linked to sunspots, much like ¹⁰Be.

⁸Be has a very short half-life of about 7×10⁻¹⁷ s that contributes to its significant cosmological role, as elements heavier than beryllium could not have been produced by nuclear fusion in the Big Bang. This is due to the lack of sufficient time during the Big Bang's nucleosynthesis phase to produce carbon by the fusion of ⁴He nuclei and the very low concentrations of available beryllium-8. The British astronomer Sir Fred Hoyle first showed that the energy levels of ⁸Be and ¹²C allow carbon production by the so-called triple-alpha process in helium-fueled stars where more nucleosynthesis time is available. This process allows carbon to be produced in stars, but not in the Big Bang. Star-created carbon (the basis of carbon-based life) is thus a component in the elements in the gas and dust ejected by AGB stars and supernovae (see also Big Bang nucleosynthesis), as well as the creation of all other elements with atomic numbers larger than that of carbon.>>

tnzkka wrote:AFAIK element 43 Tc (Technetium) is also manmade, hence it's name.
At least the Dutch Wikipedia agrees with me.
Any comment or rectification on my knowledge or on Wikipedia(Dutch)?

heehaw wrote:I thought Li, Be, B were, with He, made in the first 3 minutes?

Chris Peterson wrote:
B may not have formed in the BB at all, but if it did, it would be in trace amounts compared with what subsequently formed through stellar nucleosynthesis.

https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis#Heavy_elements wrote:
<<[Theoretically] Big Bang nucleosynthesis produced no elements heavier than beryllium, due to a bottleneck: the absence of a stable nucleus with 8 or 5 nucleons. This deficit of larger atoms also limited the amounts of lithium-7 and beryllium-9 produced during BBN. In stars, the bottleneck is passed by triple collisions of helium-4 nuclei, producing carbon (the triple-alpha process). However, this process is very slow, taking tens of thousands of years to convert a significant amount of helium to carbon in stars, and therefore it made a negligible contribution in the minutes following the Big Bang.

[However..] traces of boron have been found in some old stars, giving rise to the question whether some boron, not really predicted by the theory, might have been produced in the Big Bang. The question is not presently resolved.>>

loquin wrote:So... The chart indicates that all Helium was produced in the Big Bang. Since the major source of energy from stars on the main sequence is in the fusion of Hydrogen into Helium, has not enough helium been produced in stars to be a factor in the helium mass equation as of yet?

rstevenson wrote:

loquin wrote:So... The chart indicates that all Helium was produced in the Big Bang. Since the major source of energy from stars on the main sequence is in the fusion of Hydrogen into Helium, has not enough helium been produced in stars to be a factor in the helium mass equation as of yet?

The vast majority of Helium in the universe now was indeed produced during the first few minutes after the BB. It's true that Helium is produced in stars, but in the larger stars, where most of it is produced, the Helium in turn is "burned" to produce other elements. I can't find a source saying just what percentage of Helium currently in the universe has been star-produced, though.

ta152h0 wrote:is radioactivity the same as " cosmic ray " ?????