PSR J1930-1852: a Pulsar in the Widest Known Orbit around Another Neutron Star

In the summer of 2012, during a Pulsar Search Collaboratory workshop, two high-school students discovered J1930-1852, a pulsar in a double neutron star (DNS) system. Most DNS systems are characterized by short orbital periods, rapid spin periods, and eccentric orbits. However, J1930-1852 has the longest spin period ({{P}_spin} ∼ 185 ms) and orbital period ({{P}_b} ∼ 45 days) yet measured among known, recycled pulsars in DNS systems, implying a shorter than average and/or inefficient recycling period before its companion went supernova. We measure the relativistic advance of periastron for J1930-1852, \dot{ω }=0.00078 (4) deg yr^-1, which implies a total mass ({{M}_tot}=2.59 (4) {{M}_⊙ }) consistent with other DNS systems. The 2σ constraints on {{M}_tot} place limits on the pulsar and companion masses ({{m}_p}\lt 1.32 {{M}_⊙ } and {{m}_c}\gt 1.30 {{M}_⊙ } respectively). J1930-1852’s spin and orbital parameters challenge current DNS population models and make J1930-1852 an important system for further investigation.