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 find a unit distance graph "G" in which some pair of vertices are at distance "A" in all unit distance representations of "G" . This result implies a finite version of the Beckman–Quarles theorem: for any two points "p" and "q" at distance "A", there exists a finite rigid unit distance graph containing "p" and "q" such that any transformation of the plane that preserves the unit distances in this graph preserves the distance between "p" and "q" . The full Beckman–Quarles theorem states that any transformation of the Euclidean plane (or a higher-dimensional space) that preserves unit distances must