PASADENA, Calif. — Dating millisecond pulsars is like trying to guess the age of a patient by listening to his heartbeat.
These compact stellar remnants spin hundreds of times a second — gaining speed over time by pulling in material from a companion star — and emit beams of radio waves that sweep past Earth like a lighthouse beacon. The period between each radio pulse and the rate at which those pulses slow have been the only clues astronomers have had to estimate the age of one of these whirling dervishes. And sometimes estimates have been ludicrously off the mark, with pulsars labeled as older than the galaxies in which they reside.
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