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Questions tagged [elemental-abundances]

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1answer
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What is a “differential chemical abundance”?

Probably this is a extremely basic question, but after a lot of time searching about it without results (in all the sites/publications i've found they only use this term but there is no specific ...
2
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1answer
82 views

carbonaceous content of galaxies?

There is a phrase in a Science Daily article which appears to be wrong: The Milky Way has a very high content of carbonaceous dust, which has been shown to be very rare in other galaxies. Is there ...
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Will the detection of colliding neutron stars by LIGO help answer the question of where heavy elements came form?

I have read about and heard about the theory that most of the heavy elements we have here on Earth came from colliding neutron stars rather than by way of supernovae. I'm not sure how strong this ...
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2answers
67 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 ...
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1answer
306 views

Concerning the “Lithium test” for Brown Dwarfs

Both low-mass PMS (pre-main-sequence) stars and young brown dwarfs can fuse lithium in their cores and the lithium can be depleted throughout the star/brown dwarf very quickly. Wiki. Then the Li I ...
6
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1answer
367 views

Why are O III lines so prominent in the spectra of emission nebulae when the amount of oxygen relative to hydrogen is a million times smaller?

Looking at spectra of emission nebulae like the Lagoon Nebula, the $[\text{O III}]$ lines are prominent in intensity. However, the abundance of oxygen is minuscule compared to hydrogen. How then are ...
6
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1answer
260 views

What is the composition of the Solar Wind?

Is the composition of the Solar Wind known? I'm especially interested in the heavy metals present. Most accounts deny the existence of anything other than electrons, protons, and some alpha particles; ...
3
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1answer
106 views

How early could life supporting planets been formed?

In thinking about exclusion options for where its not worth to look for habitable planets, the past came to my mind. Right at the beginning of the universe, there was no possibility for (carbon based)...
5
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1answer
214 views

How are heavier elements such as carbon and silicon distributed within the Sun?

In a previous question I asked about the source of carbon and silicate dust that Solar Probe Plus will encounter in its close flyby of the Sun. It seems likely that most sources would include infall ...
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2answers
220 views

Is the composition of stars in future made of more and more heavy elements?

In the beginning stars only consisted of the hydrogen element and due to nuclear fusion of those elements in stars and supernova's more heavy elements were created. Because of that, like our Sun, the ...
5
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1answer
158 views

Why are certain elements so common?

I understand why hydrogen and helium are the most common elements in the universe. I also understand iron, because that's where stellar fusion stops. But why are (specifically) oxygen, carbon and neon ...
4
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1answer
98 views

How are the element abundances calculated for a meteorite in the Hydrogen log10 scale?

In astronomy, solar abundances are often calculated or tabulated per $10^{12}$ H atoms. I understand that in case of the Sun this can be done because H atoms are in majority or are present for a scale ...
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Why argon instead of another noble gas?

I noticed that the atmospheres of Earth and Mars have a little bit of argon in them (1% to 2%). I checked Venus, too, which has 0.007% argon, but that's still more than any other noble gas in the ...
2
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1answer
108 views

How to determine atomic number density of an element in a star based on equivalent width measurements

Given an equivalent width measurement $W$ of a spectral line of element $X$ and the effective temperature $T_{eff}$ of a star, how can you determine the atomic number density of $X$ in that star? ...
6
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1answer
168 views

Is any consensus forming on the solution to the “Lithium Problem”?

The "Lithium Problem" relates to the fact very-low-metallicity stars appear to have a Li/H ratio approximately one third of what would be expected. The ratio should be the same as the prediction from ...
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2answers
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Is a star powered by fission possible?

Stars can easily fuse atoms to give of heat and radiation. But at Wikipedia it said that only sub-iron atoms give of energy when fused and take energy when split, and post-iron atoms is the exact ...
10
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2answers
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Why is carbon so rare on the Moon and on Mars?

Carbon is the fourth most common element in the universe and in the Solar system. It is about the ninth most common element in Earth's crust. It doesn't seem to be part of any of the ten most common ...
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1answer
250 views

How are stellar elemental abundances quoted?

Close to the bottom of page 4 of this article (marked as page 164 in the upper left corner) states Values are given in the logarithmic scale usually adopted by astronomers, A$_{e\ell}$ = log N$_{e\...