OPTICAL-DETECTION OF THE COMPANION OF THE MILLISECOND PULSAR-J0437 - 4715

OPTICAL observations of the companion stars in binary pulsar Systems1-3 offer a way to estimate pulsar ages independent of calculations based on timing measurements of the radio pulses, and can therefore provide important constraints for models of pulsar evolution. Here we report the optical detection of the companion star of the nearby binary millisecond pulsar J0437 - 4715. The companion seems to be a very cool, quiescent white dwarf. The temperature inferred from the observations is less than that obtained from a cooling model of a white dwarf of an age equivalent to the 'spin-down' age of the pulsar. These observations provide direct support for the hypothesis1 that millisecond pulsars are long-lived objects, and that their magnetic fields do not decay.