Re: Nearby stars-why do they start at 4LY?


John C. Polasek <jpolasek@xxxxxxxxxx> writes:
Wiki et al show tables of the first 20 or 50 starsnearest the earth.
The distances for the first few are
.. .. .. 4.3 6.0 7.7 8.4 8.6 9.4 10.4 LY
1.7 1.7 .7 .2 1.2 1 the differences
Why are there no stars from 0 to 4.3 LY? From the difference list
there should be at least 2 closer than 4.3.
These are probably the few that can be measured using the parallactic
effect. It just doesn't seem likely that such a void exists.

If there are 7 stars within a radius of 10 light-years, then the
density is .00168 stars per cubic light year. Assuming a uniform
density (no voids), the cumulative number should grow as R^3.

On average, the first star will appear at a radius between 4-6 light
years, which is a reflection that the inner 5 light years contains
only about 1/8th of the total volume out to 10 light years. On
average, the next stars will be separated by 1.8, 1.1, 0.8, 0.7, 0.6,
0.5 light years respectively. Seems like a reasonable approximation
of reality to me.

CM
.

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