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enotstrebor
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In http://arxiv.org/PS_cache/astro-ph/pdf/9803/9803165v4.pdf" the authors use (second paragraph) "Spectroscopic observations of gas clouds seen in absorption against background quasars" to search for variations in alpha.
Is my understanding correct that
A) The quasars are background and they are looking at absorption peaks in a "gas cloud" between the quasar and us.
If so
B) Are they using absorption lines rather then the quasar's emission lines because the emission lines are two broad to be able to measure electron transitions used to measure alpha.
If so;
C) Since the gas cloud is somewhere between us and the quasar, how does this give alpha at the period of the quasar's redshift distance rather than at the clouds distance.
Is my understanding correct that
A) The quasars are background and they are looking at absorption peaks in a "gas cloud" between the quasar and us.
If so
B) Are they using absorption lines rather then the quasar's emission lines because the emission lines are two broad to be able to measure electron transitions used to measure alpha.
If so;
C) Since the gas cloud is somewhere between us and the quasar, how does this give alpha at the period of the quasar's redshift distance rather than at the clouds distance.
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