In article ,
greywolf42 writes:

TS The fact remains that in most publications gas rotation curves are
TS used to support the hypothesis that stars are bound by dark
TS matter.
....
It's a simple assumption that is historically used because gas
motions are so much easier to measure than stellar motions. Now it's
'carved in stone.' It's simply that there never was a theoretical or
observational justification for the assumption.

I think you will find that the original work on disk rotation
velocities used visible observations of stars. Nowadays, it's more
common to use H I because the gas can be used beyond the observed
disk. It was a huge surprise when these observations were first
done, and flat rotation curves continued beyond the radius of visible
starlight.

Can you cite any _observations_ where the gas and stellar velocities
disagree? How about locally in the Milky Way? Any disagreement
between gas (CO, H I) and stellar velocities?

Neutral gas always has a magnetic moment. Magnetic fields accelerate
neutral gas via it's paramagnetic or diamagnetic properties. It won't
accelerate neutral gas as fast as ionized gas, but the final motions should
be the same.

If this is the explanation, what magnetic field pattern do you
require? Is it consistent with observed polarization?

In other words, the force is not zero. It is significantly smaller than for
ionized gas. So it may take a year or a decade to accelerate to the same
speeds it took only seconds to accelerate the ionized gas.

And what magnetic field strength? Is that consistent with Zeeman
splitting, Faraday rotation, and synchrotron emission?

--
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
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