PSR J2222−0137

PSR J2222−0137 is a nearby intermediate-mass binary pulsar at a distance of 267+1.2
−0.9 pc (approximately 870 light-years),^[1] whose low-mass neutron star's companion is a white dwarf (PSR J2222−0137 B). The white dwarf has a relatively large mass of 1.319 ± 0.004 M_☉^[2] and a temperature less than 3,000 K,^[1] meaning it is likely crystallized, leading to this Earth-sized white dwarf being described as a "diamond-star".^[3]