Quote:
On 2002-01-17 20:44, Donnie B. wrote:
If my math is right, a redshift of .385 corresponds to about 1.3 Mpc, or 4.4 million light years. Is that about right?
(I'm using a Hubble constant of 70 km/sec/Mpc; is this value current?)
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No, your distance too low. 0.385 means (very roughly) that it is moving at 0.385 times the speed of light (this assumption fails at higher redshift, but it's a place to start). So 0.385 x 300,000 kilometers per second means it is moving at 115,000 kps. Divide by 70 gives you 1650 megaparsecs, or 1.65 gigaparsecs. That's 1.65
billion parsecs.
Remember, the Andromeda Galaxy is about 0.8 million parsecs away, and it is the closest big spiral. It is actually close enough to show a blueshift. A redshift of even 0.1 is a pretty distant object.