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3answers
96 views

The formation of absorption lines in solar spectrum

It is said that absorption lines originate from regions higher in the photosphere where the gas is cooler. The gas should be absorbing photons, then re-emitting them... absorb, re-emit, absorb, ...
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2answers
61 views

What happens to the energy from a GRB?

A gamma ray burst produces somewhere around 1044 J of energy, according to Wikipedia. Only a small portion of that energy will be absorbed by other objects. The rest of that energy will go on to ...
5
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3answers
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Is there a natural process by which hydrogen is generated from heavier elements in the cosmos?

we know that stars fuse hydrogen into helium starting at 3 MK; 13 MK in the Sun's core; carbon fusion starts at above 500 million K, and silicon fusion starts at over 2700 million K for comparison; ...
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2answers
77 views

What is radiation pressure and how does it prevent a star from forming?

This is a follow up to: Is there a theoretical maximum size limit for a star? The answer there talks about the radiation pressure preventing a star from forming. What reaction is causing this ...
7
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2answers
117 views

Where does the radiation in space come from and can we observe it?

I have recently been reading that space travel is strongly influenced by "space radiation" and how it poses a threat to human space exploration. Does this radiation originate from stars like our Sun, ...