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10h
comment the formation of absorption lines in solar spectrum
I add an image to my post. Both ionizations and recombinations take place at layer B. What the observer sees is an integrated effect. He really sees less Halpha photons? A's Halpha photons does not outnumber B.
10h
revised the formation of absorption lines in solar spectrum
added 83 characters in body
11h
comment What is the bluest narrow band filter mounted on ground based telescopes?
a quasar with z=1.7 is ok.
1d
comment the formation of absorption lines in solar spectrum
@LDC3 @Jeremy If we make two integrations at the whole surface of the photosphere. One is at the bottom surface of photosphere. The other is at the bottom surface of the photosphere. The Halpha photon numbers are the same? If they are not the same,where is the lost energy?
1d
comment the formation of absorption lines in solar spectrum
@LDC3 My confusion is why there are absorption lines. There is absorption, but there is recombination too.
1d
comment the formation of absorption lines in solar spectrum
@LDC3 Please forgive my ambiguous expression. What I mean is not about the space between the photosphere and the observer. The photons can be absorbed by the colder gas at the top of the photosphere, but there are recombinations. Although photons may be redirected, it should not the the reason of absorption line. Because photons at other regions of photosphere can be redirected to our line of our sight too. So the amount of Halpa photons really drops because of photospere?
2d
comment the formation of absorption lines in solar spectrum
There is a H-alpha absorption line(6563A) at your first link (NOVA). Although photons in our line of sight originally could be scattered and emitted in a different direction,photons at other places could be scattered to our direction. Like I said, the total amount of Halpha photons drops after they leave photosphere? Although photons could be scattered, photons at other places could be scattered to our line our sight.
2d
comment the formation of absorption lines in solar spectrum
@LDC3 Like I said, the total amount of Halpha photons drops after they leave photosphere? Although photons could be scattered, photons at other places could be scattered to our line our sight.
2d
comment the formation of absorption lines in solar spectrum
@Jeremy link
2d
comment the formation of absorption lines in solar spectrum
Jeremy means the absorption is not the main reason,but the recombination? The photons produced by recombination will have a wavelength dispersion?
2d
comment the formation of absorption lines in solar spectrum
Let's take Halpha as an example. The total amount of Halpha photons drops after they leave photosphere? Although photons could be scattered, photons at other places could be scattered to our line our sight.
2d
asked the formation of absorption lines in solar spectrum
Apr
13
awarded  Custodian
Apr
13
reviewed Approve suggested edit on What is the bluest narrow band filter mounted on ground based telescopes?
Apr
11
comment What is the bluest narrow band filter mounted on ground based telescopes?
I find someone bought a suitable filter for their Keck observation. I know the absorption by the atmosphere at 3300A on the earth is large. If we want to get a 3300A narrow image,a space telescope,i.e. hst, is necessary?
Apr
11
comment What is the bluest narrow band filter mounted on ground based telescopes?
Just want to do a narrow band photometry. I find Gemini-N (gemini.edu/?q=node/10420) has a poor response at 3300A and the u-band filter is no longer available now.What is the bluest commercially available filter? As far as you know, what is the bluest ever commissioned by a professional observatory?
Apr
9
asked What is the bluest narrow band filter mounted on ground based telescopes?
Mar
4
comment star atlas with absolute magnitude and spectral type
Thank you,Gerald. I missed your This book seems to contain a table with values as of 2009, which is cited here. It is very difficult to find sk's catalog. I do not know why vizier do not include it.
Mar
4
comment star atlas with absolute magnitude and spectral type
haha,you are professional. I have this book. I just need a catalog which people use much.
Mar
4
comment star atlas with absolute magnitude and spectral type
Thank you. This kind of thing is what I am looking for. But it seems people did not cite that MNRAS paper much. Maybe I still need the traditional schmidt-kaler catalog.