RCW 88 of a larger halo of fainter nebulosity extending perhaps out to 10 arcmin. The RCW catalogue states the Hα image size is 3'×2. RCW 88 is located about 3300 parsecs (10,000 light years) from us, though other estimates place this at a closer 1800±300 pc. or 1800±200 pc. Assuming the former distance and the diameter as 5'-6' across, finds by simple trigonometry the true size subtends a minimum of 5±1 parsecs (16±3 light-years.) This small emission nebula shows a mean radial velocity of −18 km.s, and is also a faint radio source that was identified by Lloyd Higgs in 1971.
Unit distance graph way (up to congruence) to place the vertices at distinct locations such that adjacent vertices are a unit distance apart, and this placement also puts the two endpoints of the missing spoke at unit distance . posed the problem of estimating how many pairs of points in a set of "n" points could be at unit distance from each other. In graph theoretic terms, how dense can a unit distance graph be? The hypercube graph provides a lower bound on the number of unit distances proportional to formula_1 By considering points in a square grid with carefully chosen spacing, Erdős