(Submitted January 23, 1998)
Could you please give me an estimate of the amount of stars located
within 100 light years from earth?
As a function of distance, the Gliese star catalog lists the following
number of stars. A parsec is 3.26 light years.
Distance Number Density
Distance from Sun in parsecs||number of stars||stars/cubic parsec|
The fall-off in density is probably due to the fact that many stars are too
faint to be cataloged at a distance more than 5 parsecs. (At still larger
distances, the density of stars does vary as you move outside of the local
spiral arm of our galaxy and into the less-populated regions above and
below the disk.)
Using the 0.120 stars/cubic parsec number, and using a volume for a distance
100 light-years = 100/3.26 = 30.7 parsecs
Number = density * volume
= 0.120 stars/cubic parsec * 4/3 pi (30.7 parsecs)^3
= 14,600 stars
Most of these stars are completely unknown.
for Ask an Astrophysicist