Call us toll-free

Nucleosynthesis and composition at the cosmic ray …

The atoms in your body – apart from the hydrogen – were all made in stars … by stellar nucleosynthesis

Approximate price

Pages:

275 Words

$19,50

This is known as cosmic-ray nucleosynthesis.

and and and and and and and and and and and and (2001) Constraints on the nucleosynthesis of refractory nuclides in galactic cosmic rays. In: Solar and Galactic Composition: A Joint SOHO/ACE Worshop. AIP Conference Proceedings. No.598. American Institute of Physics , Melville, NY, pp. 269-274. ISBN 0-7354-0042-3.

Cosmic Rays from Dark Matter Annihilation and Big-Bang Nucleosynthesis

In modern theory, there are a number of processes which are believed to be responsible for nucleosynthesisin the universe. The majority of these occur within the hot matterinside stars. The successive processes which occurinside stars are known as hydrogen burning (via the or the ), , , , and . Theseprocesses are able to create elements up to iron and nickel, theregion of the isotopes having the highest per nucleon. Heavierelements can be assembled within stars by a neutron capture processknown as the or in explosive environments, such as , by a number of processes. Some ofthe more important of these include the , which involves rapid neutroncaptures, the , which involves rapid proton captures, and the (sometimes knownas the gamma process), which involves of existingnuclei.

Big bang nucleosynthesis - ScienceDirect

Cosmic Rays from Dark Matter Annihilation and Big-Bang Nucleosynthesis.

Wiki is correct; stellar nucleo- synthesis doesn't produce much Boron, but there are other mechanisms: Big Bang nucleo-synthesis, nuclear reactions such as Li7 + H3 --> B10 , or production in the earth's upper atmosphere by cosmic radiation.
I'm not an expert in this but, fortunately, we have a local guru, Professor Fields who is. Unfortunately, he is on vacation right now. I'll ask him when he returns and get back to you.

LeeH

This is indeed a very interesting question. In fact, the origin of boron was long a mystery to astronomers. To give some context, one of the triumphs of 20th century astrophysics was the demonstration that the elements originate due to nuclear reactions taking place in a cosmic context--a process known as "nucleosynthesis." It was shown that the most abundant elements in the universe, hydorgen and helium, were created in the first moments of the big bang (primordial nucleosynthesis). Most of the other, heavier elements are created in nuclear reactions that go on in the enormously hot cores of stars (stellar nucleosynthesis).

But a handful of elements arise from neither process. Boron, as well as beryllium and some varieties of lithium, are not made in the big bang, nor are they made in stars.
In fact, stars *destroy* whatever lithium, beryllium, and boron they are born with.
So where are these elements made? Wherever it is, their origin must involve nuclear reactions and thus high-energy particles.

Interstellar space contains just such high-energy particles: these are the cosmic rays,
which are mostly very high-speed, energetic protons. Cosmic-ray protons move through interstellar space, where they unavoidably interact with interstellar gas. That is, cosmic-ray protons collide at high speeds and energies with the nuclei of any and all interstellar atoms.
Of interest for us are collisions between cosmic-ray protons and interstellar carbon
and oxygen nuclei (which are observed in our our Galaxy and in other galaxes).
In these collisions, the carbon and oxygen are fragmented (a process called "spallation") and the debris include the lighter lithium, beryllium, and boron nuclei. Thus boron is born in interstellar space, as a by-product of cosmic-ray irradiation! This is known as cosmic-ray nucleosynthesis. The process is not very efficient, and so boron (and lithium and beryllium) have some of the smallest abundance of any stable elements!

'soriginal work on nucleosynthesis of heavier elements in starsoccurred just after World War II. Thiswork attributed production of all heavier elements from in starsduring the nuclear evolution of their compositions, starting fromhydrogen. Hoyle proposed that hydrogen is continuously created inthe universe from vacuum and energy, without need for universalbeginning.

Title: The Revival of Galactic Cosmic Ray Nucleosynthesis

occurred within the first three minutes of the beginning of theuniverse and is responsible for much of the abundance ratios of1H (), 2H (), 3He(), and4He (),in the universe .Although 4He continues to be produced by othermechanisms (such as stellar fusion and alpha decay) and traceamounts of 1H continue to be produced by and certaintypes of radioactive decay ( and ), most of the mass of these isotopes in the universe,and all but the insignificant traces of the 3He anddeuterium in the universe produced by rare processes such as , arethought to have been produced in the . The nuclei of these elements, alongwith some 7Li, and 7Be are believed to havebeen formed when the universe was between 100 and 300 seconds old,after the primordial - plasma froze out to form and . Because of the very short period inwhich Big Bang nucleosynthesis occurred before being stopped byexpansion and cooling, no elements heavier than could be formed. (Elements formedduring this time were in the plasma state, and did not cool to thestate of neutral atoms until much later).

The products of stellar nucleosynthesis are generallydistributed into the universe through mass loss episodes andstellar winds in stars which are of low mass, as in the phase of evolution, as well as through explosive eventsresulting in in the case of massive stars.

Order now
  • Chandra :: Photo Album :: Cassiopeia A :: December 12, …

    Cosmic ray spallation is a form of naturally occurring nuclear fission and nucleosynthesis

  • Science news and information about the Sun-Earth environment.

    Big bang nucleosynthesis theory The theory of BBN consists of following the microphysics of weak and ..

  • We finally know what elements are contained in an …

    Production of A=6,7 Nuclides in the Alpha + Alpha Reaction and Cosmic Ray Nucleosynthesis Item Preview

Order now

Evidence for the Big Bang - TalkOrigins Archive: …

Long duration, large area cosmic-ray detectors, possibly on a space station, will be required to determine the abundance of elements heavier than bismuth, allowing direct comparison of cosmic-ray composition with that expected for r-process nucleosynthesis in supernova, which are suggested as the source of cosmic rays.

THE UNREASONABLE WEAKNESS OF R-PROCESS COSMIC …

The first direct proof that nucleosynthesis occurs in stars wasthe detection of in the atmosphere of a in the early1950s,prototypical for the class of . Because technetium isradioactive, with halflife much less than the age of the star, itsabundance must reflect its creation within that star during itslifetime. Less dramatic, but equally convincing evidence is oflarge overabundances of specific stable elements in a stellaratmosphere. An historically important case was observation ofbarium abundances some 20-50 times greater than in unevolved stars,which is evidence of the operation of the within that star. Many modernproofs appear in the isotopic composition of , solid grains that condensed fromthe gases of individual stars and which have been extracted frommeteorites. Stardust is one component of . The measured isotopiccompositions demonstrate many aspects of nucleosynthesis within thestars from which the stardust grains condensed

Nucleosynthesis | Wiki | Everipedia

We discuss Galactic cosmic-ray (GCR) spallation production of Li, Be, and B in the early Galaxy with particular attention to the uncertainties in the predictions of this model. The observed correlation between the Be abundance and the metallicity in metal-poor Population II stars requires that Be was synthesized in the early Galaxy. We show that the observations and such Population II GCR synthesis of Be are quantitatively consistent with the big bang nucleosynthesis production of 7Li. We find that there is a nearly model independent lower bound to B/Be of ∼7 for GCR synthesis. Recent measurements of B/Be ∼ 10 in HD 140283 are in excellent agreement with the predictions of Population II GCR nucleosynthesis. Measurements of the boron abundance in additional metal-poor halo stars is a key diagnostic of the GCR spallation mechanism. We also show that Population II GCR synthesis can produce amounts of 6Li which may be observed in the hottest halo stars.

Nucleosynthesis - Universe Today

N2 - We discuss Galactic cosmic-ray (GCR) spallation production of Li, Be, and B in the early Galaxy with particular attention to the uncertainties in the predictions of this model. The observed correlation between the Be abundance and the metallicity in metal-poor Population II stars requires that Be was synthesized in the early Galaxy. We show that the observations and such Population II GCR synthesis of Be are quantitatively consistent with the big bang nucleosynthesis production of 7Li. We find that there is a nearly model independent lower bound to B/Be of ∼7 for GCR synthesis. Recent measurements of B/Be ∼ 10 in HD 140283 are in excellent agreement with the predictions of Population II GCR nucleosynthesis. Measurements of the boron abundance in additional metal-poor halo stars is a key diagnostic of the GCR spallation mechanism. We also show that Population II GCR synthesis can produce amounts of 6Li which may be observed in the hottest halo stars.

Order now
  • Kim

    "I have always been impressed by the quick turnaround and your thoroughness. Easily the most professional essay writing service on the web."

  • Paul

    "Your assistance and the first class service is much appreciated. My essay reads so well and without your help I'm sure I would have been marked down again on grammar and syntax."

  • Ellen

    "Thanks again for your excellent work with my assignments. No doubts you're true experts at what you do and very approachable."

  • Joyce

    "Very professional, cheap and friendly service. Thanks for writing two important essays for me, I wouldn't have written it myself because of the tight deadline."

  • Albert

    "Thanks for your cautious eye, attention to detail and overall superb service. Thanks to you, now I am confident that I can submit my term paper on time."

  • Mary

    "Thank you for the GREAT work you have done. Just wanted to tell that I'm very happy with my essay and will get back with more assignments soon."

Ready to tackle your homework?

Place an order