We report on the discovery of PSR J1141-6545, a radio pulsar in an eccentric, relativistic 5 hr binary orbit. The pulsar shows no evidence of being recycled, having a pulse period P = 394 ms, a characteristic age τc = 1.4 × 106 yr, and an inferred surface magnetic dipole field strength B = 1.3 × 1012 G. From the mass function and measured rate of periastron advance, we determine the total mass in the system to be 2.300 ± 0.012 M☉, assuming that the periastron advance is purely relativistic. Under the same assumption we constrain the pulsar's mass to be Mp ≤ 1.348 M☉, and the companion's mass to be Mc > 0.968M☉ (both with 99% confidence). Given the total system mass and the distribution of measured neutron star masses, the companion is probably a massive white dwarf that formed prior to the birth of the pulsar. Optical observations can test this hypothesis.
"Discovery of a Young Radio Pulsar in a Relativistic Binary Orbit" V. M. Kaspi, A. G. Lyne, R. N. Manchester, F. Crawford, F. Camilo, J. F. Bell, N. D'Amico, I. Stairs, N. McKay, D. J. Morris, & A. Possenti, Astrophysical Journal, 543, 321 (2000).