AUSTRALIAN astronomers have chanced upon a rare type of pulsar (a word coined from pulsating star) -- a cosmic source of regular and rapid pulses of radiation, usually at radio frequencies. The pulsar is lurking at the edge of our galaxy, the Milky Way. Named PSR J0437-4715, the pulsar is a millisecond pulsar, which rotates at rates close to 1,000 cycles per second (Nature, Vol 361, No 6413).

The new pulsar may turn out to be the nearest known neutron star, which is a cosmic object that is not a true star but a remnant of one that has collapsed under its own gravitational force. Its closest competitor is the Geminga, recently identified as a pulsar. A pulsar is born when a neutron star comes close enough to its binary partner to strip off its atmosphere, thereby giving it a rapid spin. Binary stars refer to a system in which two stars revolve around a common centre of mass.