SPIN EVOLUTION OF ISOLATED NEUTRON-STARS - SPINDOWN THEOREM

A possible scenario of spin evolution of isolated neutron stars (INS) is considered. Additional arguments are given favoring a short timesca le for the ejector stage (10(7) - 10(8) yrs). A ''spindown theorem'' i s formulated and arguments of its applicability are given. The evoluti on of a neutron star at the accretion stage is considered a prediction is made that the INS periods can be as high as greater than or simila r to 5 x 10(2) s and they can be observed as X-ray sources. The idea a bout a stochastic spin-up of very old INS as a result of accretion fro m the turbularized interstellar medium is discussed, which implies tha t the INS can be spun-up and spun-down with equal probability.