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.
3-j symbol and formula_21 integers. Similar relations exist for the spin-weighted spherical harmonics if formula_22: For formula_25 a non-zero 3-"j" symbol has where formula_27 and formula_28 is a Wigner function. Generally a better approximation obeying the Regge symmetry is given by where formula_30. The following quantity acts as a metric tensor in angular momentum theory and is also known as a "Wigner 1-jm symbol", It can be used to perform time-reversal on angular momenta. Wigner 3-j symbols are related to Racah -coefficients by a simple phase: 3-j symbol In quantum mechanics, the Wigner 3-j symbols, also called 3"-jm" symbols, are an alternative