of the closest pulsars and neutron stars. The relatively high-mass pulsar (1.831 0.010 ) has a companion star PSR J2222−0137 B with a minimum mass of approximately 1.3 solar masses (1.319 0.004 ). This meant the companion is a massive white dwarf (only about 8% of white dwarfs have a mass ), which would make the system an IMBP. Although initial measurements gave a mass of about 1 solar mass for the PSR J2222−0137 B, later observations showed that it is actually a high-mass white dwarf and also one of the coolest known white dwarfs, with a temperature less than 3,000 K. PSR J2222−0137 B is likely crystallized, leading to this Earth-sized white dwarf being described as a "diamond-star", similar to the white dwarf companion of PSR J1719-1438, which lies about 4,000 light-years away. Effects Sometimes the relatively normal companion star of a binary pulsar will swell up to the point that it dumps its outer layers onto the pulsar. This interaction can heat the gas being exchanged between the bodies and produce X-ray light which can appear to pulsate, in a process called the X-ray binary stage. The flow of matter from one stellar body to another often leads to the creation of an accretion disk about the recipient star. Pulsars also create a "wind" of relativistically outflowing particles, which in the case of binary pulsars can blow away the magnetosphere of their companions and have a dramatic effect on the pulse emission. See also References External links Prof. Martha Haynes Astro 201 Binary Pulsar PSR 1913+16 Website Nobel Prize for the binary pulsar discovery Neutron Star Masses Tests of general relativity pulsar binary pulsar Radio astronomy