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using redshift of light from far galaxy
If we use the redshift of light from a far galaxy to calculate its
radial velocity away from us then use the Hubble Law to find a distance, what is this distance really? Is it A: distance from position of galaxy when it emitted its light to position of us AT THAT TIME or B: distance from position of galaxy when it emitted its light to position of us RIGHT NOW? Thank you. |
#2
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using redshift of light from far galaxy
On 4/17/10 11:22 PM, Lax wrote:
If we use the redshift of light from a far galaxy to calculate its radial velocity away from us then use the Hubble Law to find a distance, what is this distance really? Is it A: distance from position of galaxy when it emitted its light to position of us AT THAT TIME or B: distance from position of galaxy when it emitted its light to position of us RIGHT NOW? Thank you. Distance is more typically determined by brightness and the inverse square law. Cosmic expansion (apparent radial velocity) by red shift. BTW, you may be interested in: http://www.astro.ucla.edu/~wright/CosmoCalc.html |
#3
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using redshift of light from far galaxy
On Apr 18, 8:08*am, Sam Wormley wrote:
On 4/17/10 11:22 PM, Lax wrote: If we use the redshift of light from a far galaxy to calculate its radial velocity away from us then use the Hubble Law to find a distance, what is this distance really? Is it A: distance from position of galaxy when it emitted its light to position of us AT THAT TIME *or B: distance from position of galaxy when it emitted its light to position of us RIGHT NOW? *Thank you. * *Distance is more typically determined by brightness and the inverse * *square law. Cosmic expansion (apparent radial velocity) by red shift. * *BTW, you may be interested in: * * *http://www.astro.ucla.edu/~wright/CosmoCalc.html If we take the apparent radial velocity and divide it by the hubble constant, what distance do we get? |
#4
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using redshift of light from far galaxy
On Apr 19, 9:35*pm, Lax wrote:
On Apr 18, 8:08*am, Sam Wormley wrote: On 4/17/10 11:22 PM, Lax wrote: If we use the redshift of light from a far galaxy to calculate its radial velocity away from us then use the Hubble Law to find a distance, what is this distance really? Is it A: distance from position of galaxy when it emitted its light to position of us AT THAT TIME *or B: distance from position of galaxy when it emitted its light to position of us RIGHT NOW? *Thank you. * *Distance is more typically determined by brightness and the inverse * *square law. Cosmic expansion (apparent radial velocity) by red shift. * *BTW, you may be interested in: * * *http://www.astro.ucla.edu/~wright/CosmoCalc.html If we take the apparent radial velocity and divide it by the hubble constant, what distance do we get? Quasars have two redshift sources. The first is gravitational the other is distance. Quasars are distributed equally throughout the universe. Mitch Raemsch |
#5
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using redshift of light from far galaxy
On 4/19/10 11:35 PM, Lax wrote:
On Apr 18, 8:08 am, Sam wrote: On 4/17/10 11:22 PM, Lax wrote: If we use the redshift of light from a far galaxy to calculate its radial velocity away from us then use the Hubble Law to find a distance, what is this distance really? Is it A: distance from position of galaxy when it emitted its light to position of us AT THAT TIME or B: distance from position of galaxy when it emitted its light to position of us RIGHT NOW? Thank you. Distance is more typically determined by brightness and the inverse square law. Cosmic expansion (apparent radial velocity) by red shift. BTW, you may be interested in: http://www.astro.ucla.edu/~wright/CosmoCalc.html If we take the apparent radial velocity and divide it by the hubble constant, what distance do we get? One need to know absolute brightness. Type Ia supernovae make reasonable "standard candles". |
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