Re: Binary stars

[Joel Rauber <Joel_Rauber@SDSTATE.EDU>]

I am not aware that the terminology is as set in stone as Leigh suggests.
Which means things can be more confusing then they should be.  He is right,
of course, that the symmetry of a geometric infinite cylinder and a
geometric circle are different; one involving an ignorable z-coordinate.
I'd suggest that all readers beware, as often references to cylindrical
symmetry don't necessarily mean ignorable z-coordinate.  Which makes me
agree that terminology is important.

BTW Leigh, How do you distinguish with your terminology the difference
between an infinite cylinder and a finite length cylinder?

I might add for folks' information; that one often sees the term "axial
symmetry", which I believe to be the as the "azimuthal symmetry" to which
Leigh refers.

Joel Rauber
Joel_Rauber@sdstate.edu

> I think circular and cylindrical symmetry are different animals.
> Cylindrical symmetry entails  also an ignorable *z-coordinate*. There
> are quantum mechanical *solutions* to cylindrically symmetrical
> physical systems which do have circular symmetry except only in the
> sense that the phase of the wave function in the azimuthal direction
> is arbitrary unless it is split by some externally applied term. m=0
> corresponds to circular symmetry. Circular symmetry is a subgroup of
> cylindrical symmetry. I is also called "azimuthal symmetry".
>
> I think the terminology is important.
>
> Leigh