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comment What is the bluest narrow band filter mounted on ground based telescopes?
Thank you. z=1.7 may be marginally unacceptable.
Apr
22
comment What is the term for a star swallowing another star?
He just forgot its pronunciation. You can take a look at Py-ser's post below.
Apr
22
comment What is the term for a star swallowing another star?
@Py-ser do you know any similar paper that study how a small black hole goes through a star?
Apr
22
comment What is the term for a star swallowing another star?
@Py-ser Yes,TZO is what I heard. I do not know why there is not an accretion disk formed. Because generally there is angular momentum and a disk is necessary.
Apr
21
asked What is the term for a star swallowing another star?
Apr
21
comment What is the bluest narrow band filter mounted on ground based telescopes?
I tried to register but failed. U band is too wide. I need a narrow band image. sigh, maybe hst is necessary.
Apr
21
comment The formation of absorption lines in solar spectrum
There are many kinds of emission line sources say,PN and HII. The main channel of energy release for PN is just several emission lines. That is not strange.Just different radiation mechanism.But I do not understand the simple absorption line.
Apr
21
comment The formation of absorption lines in solar spectrum
@LDC3 from Jeremy's second link. (astronomy.nju.edu.cn/~lixd/GA/AT4/AT416/HTML/AT41603.htm)
Apr
21
comment The formation of absorption lines in solar spectrum
I add Figure16.9 to my post. We just compare the total amount of Halpha photons at different layers. The amount of Halpha photons at A is larger than B. If the main reason is not your 'including back down!', where are the reduced Halpha photons?
Apr
21
revised The formation of absorption lines in solar spectrum
added 83 characters in body
Apr
21
comment What is the bluest narrow band filter mounted on ground based telescopes?
Of course we talk about this problem under the premise that 3300A falls in the wavelength range. I should say larger than 1.7. 3300A low a response at a CCD's blue edge. It is marginal and maybe be not feasible. I do not know whether it is worth a try. I need to know how much feasibility is left.
Apr
20
comment The formation of absorption lines in solar spectrum
yes, you are right. My mistake.
Apr
20
comment What is the bluest narrow band filter mounted on ground based telescopes?
Yes, the lowest redshift in their table 1 is 1.7. However their surveys are spectroscopic, a redshift lower than 1.7 is OK too.They can use other lines except lyman alpha.
Apr
20
comment The formation of absorption lines in solar spectrum
We can argue every layer of photosphere is a black body,right?
Apr
20
comment The formation of absorption lines in solar spectrum
The main reason is 'including back down!',right?
Apr
18
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.
Apr
18
revised The formation of absorption lines in solar spectrum
added 83 characters in body
Apr
18
comment What is the bluest narrow band filter mounted on ground based telescopes?
a quasar with z=1.7 is ok.
Apr
17
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?
Apr
17
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.