Questions tagged [electromagnetic-spectrum]
Questions about a certain range of frequencies of electromagnetic radiation, given e.g. as wavelengths or wavenumbers. Consider using the tag "wavelength" as well.
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What is the difference between albedo and Bond albedo?
Recently I came across Bond albedo, but I am not sure I grasped the difference (if there is any) between it and the "classical" albedo. Thanks in advance
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Number of neutron stars by radiation band
Since the number of known neutron stars ain't reached yet 4000 at the time of writing, I am wondering about how neutron stars are classified in terms of their radiation spectrum. Clearly, some neutron ...
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Why is the H-alpha line slightly shorter in wavelength (656.28 nm) in air than in vacuum (656.46 nm)? Shouldn't it be longer?
Perhaps this is a question better suited for Physics SE, but since the H-alpha line is so important in astronomy, I'm posting this here....
I would, naively, assume that wavelengths would be longer, ...
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do we observe emission spectrum? [duplicate]
When light generated by the fusion in the sun goes through the layers of the sun and finally reaches outer layers and in the end atmosphere of the sun, we know it goes through hydrogen for example. ...
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why couldn't atoms form in the early big bang?
I'm asking about the time when temperature was super high, but at that time we already had proton, neutron, electrons.
It seems they were moving super fast due to temperature being so high.
What I'm ...
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Natural line width from absorption lines
Emission lines have a certain natural width. Due to the uncertainty principle systems that spontaneously decay or produce radiation have a fundamental energy blur, and their radiation has a ...
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Does the luminosity of a star have the form of a Planck curve?
Figure shows the intensity of the radiant energy emitted from stars A and B over a unit time according to the wavelength. The area between the graph and the horizontal axis is S and 4S, respectively.
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The Relationship between Surface Temperature and Mass of MS and Red Giant
The assumptions about the problem situation are as follows :
The red giant is in the HB at HR disgram, and it's a helium fusion situation. And in this situation, the mass of the red giant is the ...
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What are the typical emissions of Jupiter's Aurorae?
I'm looking for some solid measurements of the full range of emissions from the Aurorae on Jupiter. I've found partial sets of data in the past which are most easily summarized here. As you can see, ...
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How are absorption cross sections calculated?
I would like to develop a more intuitive understanding of cross sections, in the context of radiative transfer.
I understand that a cross section, $\sigma_\nu$, is a measure of a given atom/molecule's ...
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How luminous does a brown dwarf have to be to illuminate an Earth-sized planet with 0.5 lux at 2,000,000 kilometers away?
A brown dwarf is a deuterium-fusing substellar object, and, in the cases of the larger ones, a lithium-fusing one. They often emit electromagnetic radiation in frequencies that humans cannot see. ...
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Do free protons and neutrons absorb much radiation? To affect astronomers' observations? If so, at what wavelength(s)?
In a plasma, or wherever, do the completely ionized nuclei commonly absorb much EM radiation? Or any free neutrons or protons? Can astronomers detect this? Enough so that astronomers take it into ...
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color of stars and temperature
I recently got questioned on why stars are the color they are. I know the color of a star depends on its surface temperature where hotter stars produce more light towards the blue side of the spectrum ...
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Why isn't most hydrogen in the universe molecular (diatomic), instead of atomic (monoatomic)?
Similar questions have been asked before; but, why?
Is the monoatomic hydrogen left over from the Big Bang? And hasn't had the opportunity to collide with other hydrogen atoms yet?
Or are hydrogen ...
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What would it take to view "the whole EM spectrum"?
I know the EM spectrum goes off both ends, but nearly everything anyone has bothered to use it for has wavelengths between $10^8$m (ELF) and $10^{-12}$m or so (gamma rays). So for the purposes of this ...
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