P1021 - An ongoing study of two unusual, slow and variable binary pulsars.

Brief description Pulsars (rapidly-rotating, highly-magnetised neutron stars) are fascinating celestial objects, and pulsars in binary systems (about 11% of all known pulsars) are of particular interest. Binary pulsars can reveal information about how stars evolve, or they can provide laboratories for testing gravitational theories like Einstein’s General Relativity. The majority of binary pulsars are among the fastest-spinning pulsars, spinning more than 30 times a second, and we understand them reasonably well. Meanwhile, binary pulsars which spin much slower are much rarer, and present questions as to the processes by which their binary systems have evolved. This project aims to study two particular binary pulsars which spin slowly, roughly once every second. PSR J1812-15 is in a small, 20-hour circular orbit around an object roughly half the mass of the Sun, and is often obscured by a cloud of debris coming from its companion. This pulsar is so rare that we know of only one other pulsar that behaves anything like it. We hope to monitor this pulsar for unusual behaviour and to further refine its properties. Meanwhile, PSR J1831-04 looks extremely similar to J1812, but has never been seen again after it was first observed in 2012. We hope to redetect this pulsar so as to learn more about it and find out if it behaves the same way as J1812.