PSR J0210+5845: Ultra-wide binary pulsar with a B6 V main sequence star companion

Vol. 682
7. Stellar structure and evolution

PSR J0210+5845: Ultra-wide binary pulsar with a B6 V main sequence star companion

A neutron star forms in the explosion of a massive star as a supernova. When the exploding star is part of a binary system, the binary usually gets disrupted. In favorable conditions (e.g., asymmetries in the supernova explosion), however, the binary system can survive, leaving a newborn neutron star orbiting a massive companion. If the light beam of the radio pulsar associated with the neutron star intercepts our line of sight, we can detect the system. Until recently, only six such binaries had been known, a testament to their rarity. Van der Wateren and colleagues report here on the seventh such system. The orbital period is loosely constrained to ~47 years, with a moderate orbital eccentricity of ~0.5. At variance with all the other known binary systems, the mass of the companion star is low, ~3.6 solar masses, requiring more stringent constraints on the asymmetry of the supernova explosion. The next periastron passage will occur in 2030-2034, but the neutron star will still be too far away from the companion to expect any X-ray emission or perturbation of the radio signal.