A Parsec

(abbreviated pc) A convenient unit for measuring stellar distances, which is the distance of a star that produces a parallax angle p of 1 arc sec.

\(d=(3.09\times 10^{13})/p(“)\)\(km/arc \ seconds\)

\[d(pc)=1/p(“)\]

so:

\[1 pc=2.06\times 10^5\ AU\]

\[1 pc=3.09\times 10^{13}\ km\]

\[1 pc=3.26\ light\ years\]