Optical spectroscopy and photometry of the companion of the bright millisecond pulsar J 0437-4715

If the latter age is correct, the difference potentially raises questions about the spin-down mechanism of millisecond pulsars, which may not be dominated by the braking effect of the magnetic dipole. The relatively old age would also support previous suggestions that the decay of pulsar magnetic fields asymptotically terminates at a level of 1O⁸ - 1O⁹ G. It might furthermore reduce the discrepancy between the presently observed numbers of low-mass binary pulsars and low-mass X-ray binaries which are thought to be the progenitors of the former. On the other hand, more recent radio observations suggest a dynamical age of the pulsar of 2 Gyr which agrees well with the cooling age of its companion.