PSR B1620-26 PSR B1620-26 PSR B1620-26 is a binary star system located at a distance of 3,800 parsecs (12,400 light-years) in the globular cluster of Messier 4 (M4, NGC 6121) in the constellation of Scorpius. The system is composed of a pulsar (PSR B1620-26 A) and a white dwarf star (WD B1620-26 or PSR B1620-26 B). As of 2000, the system is also confirmed to have an extrasolar planet orbiting the two stars. The double system ("triple" including the substellar companion) is just outside the core of the globular cluster. The age of the cluster has been estimated to be about 12.2
3-j symbol more symmetrical than the C-G coefficient. Since the state formula_5 is unchanged by rotation, one also says that the contraction of the product of three rotational states with a 3-"j" symbol is invariant under rotations. The Wigner 3-"j" symbol is zero unless all these conditions are satisfied: A 3-"j" symbol is invariant under an even permutation of its columns: An odd permutation of the columns gives a phase factor: Changing the sign of the formula_11 quantum numbers (time-reversal) also gives a phase: The 3-"j" symbols also have so-called Regge symmetries, which are not due to permutations or time-reversal. These symmetries