Pulsars have historically been classified into different categories — but the distinction between them may be blurrier than we thought. The discovery of the youngest pulsar yet observed is now raising questions about how we classify these extreme objects.
The Source of a Pulsar’s Power
Artist’s illustration of an accretion-powered pulsar (left) and its small stellar companion (right), viewed within their orbital plane. [NASA Goddard SFC/Cruz deWilde]When a massive star explodes as a supernova at the end of its lifetime, an incredibly dense remnant with the mass of one or two Suns — but spanning only 20 km or so in diameter — is left behind. If this resulting neutron star is powerfully magnetized, it can emit a beam of radiation that sweeps across the Earth as the star spins, appearing to us as a pulsar.
The pulsars that we’ve observed are classified into three categories based on what we think powers their emission:
Usually detected from their pulsed radio emission, this is the most commonly observed type of pulsar. These rapidly rotating stars gradually spin down over time. Their lost rotational energy powers the particle acceleration that produces the emission we observe.
These pulsars occur ...