Re: Relationship between magnitude and distance

On Fri, 27 May 2005 01:20:17 GMT, "David Nakamoto"
<res07oeg@xxxxxxxxxxx> wrote:

>Oh come now. You're talking about a globular with a few thousand stars or so,
>compared to a galaxy with billions and billions of stars (sorry about that Carl
>! ^_^ ), a million times the amount.
>
>I still don't buy it.

The analysis I did was for a million star cluster like M13, with a
central density similar to that in galactic cores. Of course, there are
far fewer stars, but the idea remains the same- whether a cluster or a
galaxy, from a volumetric standpoint either is largely empty space.

Just think about your *** of paper idea. Take a section through a
large spiral galaxy. That can probably be treated as a disk around 5 kpc
in diameter, or around 1e9 AU. Lets populated that one, thin disk with a
billion stars about the size of the Sun, or 0.01 AU diameter. The ratio
of occupied area to unoccupied area is 1e13. I think you could lie a
random vector on this disk and have very little chance it would touch a
single star, which is another way of saying you could look across this
section of galaxy from one side to the other and not see a single star
in your path, let alone two on the same line.

Of course, extinction from dust will prevent seeing very far through
most galaxies.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
.