Radial Velocity Curves

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by DonW</i>
<br />If the redshifts that are being measured for a Spectroscopic Binary are caused by energy loses due to varying distances of the orbiting body from the observer instead of the radial velocities of the orbiting body, what implications does this have for all the calculations that have been done with these measurements?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">No theory proposes that. The "energy loss" theory of redshift applies only over cosmological distances, and might explain why all but the nearest galaxies are redshifted. But the spectral lines in stars have only Doppler shifts. They are too close for significant energy loss. -|Tom|-

tom, How do you know a doppler shift in a stellar spectrum from other redshift? What makes the difference in spectra shifts caused by any one type of shift?

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Jim</i>
<br />How do you know a doppler shift in a stellar spectrum from other redshift? What makes the difference in spectra shifts caused by any one type of shift?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">The spectral shifts alone do not reveal their cause. But in the case of double stars, the spectral shifts are constantly changing, and we can see the stars revolving around one another in phase with the shifts. So there is not much room for doubt about cause and effect for spectral shifts in double stars. -|Tom|-

Why is there no room for doubt if as you say they are too close to measure a Hubble redshift? How can you be sure there is not a tiny bit that is Hubble in nature rather than Doppler?

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Jim</i>
<br />Why is there no room for doubt if as you say they are too close to measure a Hubble redshift? How can you be sure there is not a tiny bit that is Hubble in nature rather than Doppler?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">There is "a tiny bit". It's just negligible. The Hubble redshift is roughly 65 km/s/Mpc. That's only 0.000065 km/s/parsec. Fot a typical double star a few tens of parsecs away, that is still too small to matter for most purposes.

And I did say "little room", not "no room". -|Tom|-

The use of two factors to determine the dynamics of a star system seems to add something to the result. And since it is available why not use the two redshift factors when doing spectral readings?