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[sci.math, sci.physics.relativity snipped]
In article <v72bg2d907ghe3loa0vceetvhbssemetgn@xxxxxxx>,
Lester Zick <dontbother@xxxxxxxxxxx> writes:
> The flatness of orbital velocities throughout
> Andromeda is best explained by a disk of uniform density inverse
> square gravitationally attractive matter much as the galaxy appears to
> be in purely visual terms.
In "visual terms," the surface brightness of the M31 disk decreases
exponentially with a scale length of about 5 kpc. (I'm not surprised
a radio interview failed to make that clear.)
As others have noted, the same pattern of a flat rotation curve but
decreasing mass (for an assumed constant mass-to-light ratio) is
observed in a great many galaxies; it is nothing peculiar to M31.
--
Steve Willner Phone 617-495-7123 swillner@xxxxxxxxxxxxxxx
Cambridge, MA 02138 USA
(Please email your reply if you want to be sure I see it; include a
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