Questions tagged [nucleosynthesis]

Questions to do with how new atomic nuclei are created inside the universe.

Filter by
Sorted by
Tagged with
2 votes
2 answers
72 views

Where can I find the $\mu$ value in galaxy clusters for ideal gas law?

I am studying hydrostatic equilibrium in galaxy clusters and encountered the following expression: $P=(kT/\mu m_p)\rho$ The interpretation of this formula is obvious. It is just the ideal gas law ...
Youngsub Yoon's user avatar
2 votes
1 answer
90 views

Is there a way to compare input and output energy of solar fusion to the input and output energy of man made fusion?

The Livermore fusion experiment was said to be 2 megajoules of energy in and 3 megajoules of energy out. However upon closer inspection the facility used 300 megajoules of energy. So man made uses 300 ...
Sedumjoy's user avatar
  • 1,201
22 votes
2 answers
5k views

Do stars become more metal-rich as they evolve?

Since we determine the metallicity of a star ([Fe/H] or Z) from surface emission, does this change as it ages? For instance, can a young star with a measured [Fe/H] of -0.02 have a higher value when ...
Jack R. Woods's user avatar
6 votes
3 answers
305 views

In layman's terms, why does the cold C-N-O process end in Carbon?

I read up a little bit on fusion in stars, layman's articles only and the P-P chain makes hydrogen or Alpha particles. (error removed on triple-alpha), then the C-N-O process adds hydrogen to the ...
userLTK's user avatar
  • 24k
0 votes
0 answers
61 views

Why alpha-process cannot work beyond iron? [duplicate]

In the book The Synthesis of Elements by Giora Shaviv (Springer, 2012) on page 383 is the following set of reactions and statement about alpha-process: "The process cannot go beyond iron because,...
Leos Ondra's user avatar
  • 1,074
3 votes
1 answer
157 views

In the context of stellar nucleosyntheis, is Xenon-130 a primary or secondary isotope?

With the definitions: 'a primary isotope is any isotope which can be synthesised in a star which starts its life containing only hydrogen and helium', and a secondary isotope is any isotope which ...
ryani42's user avatar
  • 131
0 votes
0 answers
39 views

In the context of stellar nucleosyntheis, is Xenon-130 a primary or secondary isotope? [duplicate]

With the definitions: 'a primary isotope is any isotope which can be synthesised in a star which starts its life containing only hydrogen and helium', and a secondary isotope is any isotope which ...
ryani42's user avatar
  • 131
1 vote
1 answer
83 views

Does the core of the sun bounce around because of turbulent hot gas around it?

How much does the core of the sun wobble and does this affect light reaching the Earth?
user avatar
2 votes
1 answer
74 views

How are the products of stellar nucleosynthesis sorted as found in planets?

Stellar nucleosynthesis is responsible for creating the elements heavier than lithium (except perhaps some of the heaviest that might result from neutron star collisions). Eventually, the star goes ...
Moshe Feder's user avatar
1 vote
2 answers
88 views

How to look up "all things astrophysical" about A=9 (or other light isobars)?

All the light isobars (group with same atomic number mass) are interesting and quirky, but let's use A=9 as an example. 9C and 9Li beta decay to particle unbound states in 9B and 9Be (except to 9Be's ...
uhoh's user avatar
  • 31.1k
2 votes
1 answer
106 views

Can the JWST track element abundances throughout time? Would this be of any interest at all?

Now that the JWST is peering further and further back into the cosmos, I came to a few questions that I would love to see answered. We know that models of the big bang nucleosynthesis result in ...
Maximal Ideal's user avatar
5 votes
2 answers
335 views

Do the newly-created deuterons in our Sun release any photons? In addition to a positron and an electron neutrino?

Perhaps this is a nuclear physics question, but.... When two colliding protons deep inside our Sun finally turn into a deuterium nucleus or deutron (after approximately ten octillion chances, on ...
Kurt Hikes's user avatar
  • 5,077
3 votes
1 answer
606 views

Why do stars usually stop fusion at iron, even though nickel-62 has the highest binding energy per nucleon?

We know that iron is often regarded as 'nuclear ash' because of its inability to fuse with other atoms, as it has a high binding energy per nucleon. However I found that Nickel-62, grabs the title of ...
Kshitij Kumar's user avatar
0 votes
1 answer
126 views

Are there any naked-eye visible stars in our Milky Way that are particularly rich in calcium? (I'm just curious)

There are Calcium-rich supernovae but here I'm asking about stars that one might see in the night sky. I'd like to ask if there are any naked-eye (or binocular-assisted) visible stars in our Milky Way ...
dnatech's user avatar
  • 39
4 votes
1 answer
115 views

Can I "see" nucleosynthesis in R Geminorum with a small telescope, a plastic diffraction grating and a cell phone? (famous technetium lines)

R Geminorum is a magnitude +6 to +11 variable star notable for the discovery of technetium spectral lines. As the longest lived isotope is only a few million years, this was direct evidence that ...
uhoh's user avatar
  • 31.1k
1 vote
1 answer
177 views

Why is the carbon/oxygen ratio at low metallicities important to study?

Oxygen and carbon are the most abundant elements in the Universe (formed via stellar nucleosynthesis), following only hydrogen and helium (formed via the Big Bang). There seems to be a lot of work to ...
quantumflash's user avatar
1 vote
0 answers
58 views

How sensitive are early universe abundance calculations to the neutron half-life?

Phys.org's Physicists announce the world's most precise measurement of neutron lifetime discusses the accepted for publication Phys. Rev. Letter Improved neutron lifetime measurement with UCNτ (links ...
uhoh's user avatar
  • 31.1k
5 votes
1 answer
263 views

Why is it that lithium and deuterium are burned before hydrogen?

Protium ($^1H$) has a nuclear binding energy near 0. Meanwhile, lithium and deuterium have higher binding energies. Why is it that they are burned first (or at lower temperatures)? Is it perhaps ...
WarpPrime's user avatar
  • 6,653
3 votes
0 answers
81 views

Elements of celestial bodies

Could someone tell me if it proceeds as well as which or which works would allow us to conclude the origin of the elements for different types of bodies or celestial phenomena? Edited: This image was ...
Octupos's user avatar
  • 151
13 votes
1 answer
2k views

Is oxygen an alpha element?

Type II (core-collapse) supernovae occur shortly after star formation and enrich a galaxy with $\alpha$ elements such as O, C, NE, Mg, Ca and Si. On the other hand, Type Ia supernovae occur on a more ...
quantumflash's user avatar
2 votes
1 answer
170 views

Spectral lines of the Sun?

If I remember correctly, the pp chain and (partially) the CNO cycle are the dominating set of reactions in our Sun. On the other hand, the composition of the Sun has many more elements/isotopes than ...
B--rian's user avatar
  • 5,616
1 vote
0 answers
84 views

Photodisintegration vs Spallation

Is photodisintegration belongs to a form of spallation? Is photodisintegration only limited to nucleus hit by high energy gamma-ray, whereas the nucleus in spallation can be hit by any ​high energy ...
Jack the Ranger's user avatar
2 votes
2 answers
233 views

Does Alpha Process Produce Bismuth?

In the book "Horizons: exploring the universe-Cengage learning (2018)", p200, it states that: Helium fusion produces carbon, and some of the carbon nuclei absorb helium nuclei to form ...
Jack the Ranger's user avatar
3 votes
1 answer
619 views

Does Oxygen-burning process produce Neon?

In the book "Horizons_ exploring the universe-Cengage learning (2018)", p200, it states that: Helium fusion produces carbon, and some of the carbon nuclei absorb helium nuclei to form ...
Jack the Ranger's user avatar
1 vote
0 answers
77 views

Can someone tell me the contribution of s-, r-, and p-isotope processes to copper?

I have looked for relevant information in the paper Chemical evolution with rotating massive star yields II. A new assessment of the solar s- and r- process components before, but unfortunately, it ...
Ddjz's user avatar
  • 11
2 votes
0 answers
77 views

How do we know or predict which particles were present before Big Bang Nucleosynthesis occurred?

I'm reading Carroll and Ostlie's "An Introduction to Modern Astrophysics". In the BBN section, they describe that the universe contains a mixture of photons, electron-positron pairs, and ...
Astroturf's user avatar
  • 1,111
4 votes
0 answers
55 views

Expanded element (and molecule) abundance graph?

There is the "classical" nucleosynthesis timeline chart where the $\log ({\rm mass \,fraction})$ is plotted as a function of $\log(t)$ where $t$ is in seconds after the big bang, looking e.g....
B--rian's user avatar
  • 5,616
2 votes
1 answer
166 views

Why does this nucleogenesis table not label s and r-processes for all elements (not-labmade) past Fe?

I'm reviewing nucleogenenesis and came across the table below. I like it because it actually labels the s and r-process elements, but I became confused as to why the neutron capture processes begin at ...
Astroturf's user avatar
  • 1,111
15 votes
3 answers
2k views

Formation of elements in the Sun other than helium

I just learned that the Fraunhofer lines of the Sun's spectrum indicate that the Sun contains various elements other than just hydrogen and helium (for example, Na and Fe) but don't the Sun's p-p ...
Jack the Ranger's user avatar
2 votes
1 answer
247 views

Would dropping a white dwarf or a "still-hot" stellar core into a large planet or brown dwarf create a star?

In the Wikipedia article about stellar engineering, I found this quote: In The Saga of the Seven Suns, by Kevin J. Anderson, humans are able to convert gas giant planets into stars through the use of ...
WarpPrime's user avatar
  • 6,653
2 votes
0 answers
73 views

Relation between core mass and red giant mass?

Yes, the title might be confusing (I'd appreciate some more clarification on it :D ). I have an estimated mass of hydrogen in the core of a star, and how much hydrogen will be in the core when the ...
WarpPrime's user avatar
  • 6,653
5 votes
1 answer
1k views

What is the length of time for each fusion process in a massive star?

In a massive star (i.e. an O5 star), first hydrogen is fused into helium, then helium is fused into carbon. This process continues to neon, oxygen, and finally silicon burning. So I am wondering, how ...
WarpPrime's user avatar
  • 6,653
2 votes
0 answers
48 views

Mass required for a certain fusion process

Suppose we have a density model $$ρ = ρ_c (1-r/R)$$ where $ρ$ is density, ${}_c$ means central, and $R$ is the stellar radius. Let's call the temperature for that fusion process to begin, $T_f$. I ...
omysoulll's user avatar
26 votes
1 answer
5k views

Is lithium considered a metal in astronomy?

My lecture notes are conflicting on this issue so I seek definitive clarification. In Astronomy, are metals either A: the elements which form within stars (i.e., not Big Bang nucleosynthesis, where ...
zabop's user avatar
  • 481
1 vote
2 answers
151 views

How can I estimate the initial luminosity of a SNIa given initial mass of Ni-56?

The initial portion (and peak) of a SNIa's light curve is powered by the $\beta$-decay reaction: $$ ^{56}Ni \rightarrow ^{56}Co + e^+ + \nu_e + \gamma $$ Supposing we know how much Ni-56 is created in ...
notadoctor's user avatar
15 votes
1 answer
722 views

What effects besides "mass defect" cause the alpha ladder beyond iron-56/nickel-56 to be endothermic?

Many sources state that fusion beyond iron-56/nickel-56 (and certainly beyond nickel-62) is impossible due to them being among the most tightly bound nuclei. For example, in the Wikipedia article on ...
HeatherB's user avatar
  • 151
33 votes
1 answer
4k views

Why don’t supergiants at least start to fuse nickel into even heavier elements before going supernova?

The last primary fusion process to take place in extremely massive stars is silicon burning, where the 28Si produced by oxygen burning is exothermically fused with alpha particle after alpha particle ...
Vikki's user avatar
  • 625
2 votes
0 answers
58 views

How scientists estimated the number of near-Earth supernovae over the last 11 million years?

According to this article on wikipedia, An estimated 20 supernova explosions have happened within 300 pc of the Earth over ...
user avatar
0 votes
0 answers
28 views

How did the amount of nuclide produced by s- and r-process changed over time?

For a exercise I need to find out how the amount of nuclide produced by s- and r-process changed over time and I also need to draw a schematic diagram of the s-/r-ratio vs. time from 13.6 Ga till ...
helpless student's user avatar
5 votes
0 answers
84 views

Neutron star r-process nucleosynthesis

The $r$-process in supernovae happens when a high flux of neutrons irradiates the heaviest abundant nuclei (in the region of iron), resulting in endothermic nuclear reactions. To the extent that at ...
Martin Kochanski's user avatar
9 votes
1 answer
343 views

What percentage of Helium-3 is primordial vs produced in stars

I tried to research but what I found is pretty limited. A very tiny but non zero percentage of primordial matter was Helium-3 or 3He. Stars produce 3He as part of the proton-proton chain but they ...
userLTK's user avatar
  • 24k
28 votes
2 answers
4k views

Are we really star-stuff from the interior of collapsing stars?

Carl Sagan has said several times that we are "star-stuff". One instance can be found in Good Reads' Carl Sagan > Quotes > Quotable Quote: The nitrogen in our DNA, the calcium in our teeth, the ...
uhoh's user avatar
  • 31.1k
15 votes
2 answers
5k views

Does a star fuse helium to beryllium on the main sequence?

When a star has finished fusing all its hydrogen into helium, it will then start fusing helium into beryllium and so on and so forth up until iron. When the star is fusing to beryllium, will the ...
MiscellaneousUser's user avatar
6 votes
1 answer
262 views

Do we know how old the matter that makes us is?

Last weekend, I had the pleasure of visiting an observatory where there was a series of lectures to cover up the fact that there was too much cloud cover to actually observe much at all. One of these ...
user avatar
2 votes
0 answers
54 views

How the observed deuterium abundance constrains big bang nucleosynthesis?

I know deuterium can be used as a good tracer to constrain the big bang nucleosynthesis. But can anyone tell me the in details how this is actually done?
Arpan Das's user avatar
  • 187
2 votes
0 answers
64 views

pp-Chain reactions involving $^{3}_{2}He$ - differences in S-factor

So I was looking at the pp-chain reactions that take place inside stars in a bit more detail. I got confused about the massive differences in reaction efficiencies concerning two reactions $^{3}_{2}He$...
AtmosphericPrisonEscape's user avatar
3 votes
1 answer
420 views

"Turn on point" for fusion?

I've read that when a body reaches about 13 times the mass of Jupiter that deuterium fusion starts and the body becomes a brown dwarf instead of a planet. I have a multiple question. Are there any ...
Jack R. Woods's user avatar
1 vote
2 answers
232 views

Can you recommend a book about big bang nucleosynthesis and chemical abundances?

I am interested in learning about big bang nucleosynthesis, nuclear fusion up to iron in stellar cores and beyond iron in supernovas, and into the lithium problem (galactic abundance anomoly for ...
user avatar
3 votes
1 answer
209 views

Ionization Fraction of Helium in alternate, He dominated early universe

I'm asked to verify an expression for the ionization fraction of helium in a universe in which helium dominates baryonic matter. I'm given that the ionization fraction $X = \frac{n_{He^+}}{n_{He^+}+...
Spuds's user avatar
  • 105
31 votes
1 answer
7k views

Why didn't the Big Bang produce heavier elements?

Shortly after the Big Bang, temperatures cooled from the Planck temperature. Once temperatures lowered to 116 gigakelvins, nucleosynthesis took place and helium, lithium and trace amounts of other ...
Sir Cumference's user avatar