Compact binary millisecond pulsars are captivating celestial objects comprised of fast-spinning neutron stars orbiting closely with lighter companion stars. Neutron stars are ultra-dense remnants of massive stars resulting from supernova explosions at the culmination of their lifecycles. These binary pulsars exhibit distinct behaviors due to intense gravitational interactions between the stars. Pulsars emit particle “winds” due to rapid rotation, significantly influencing their lighter companions. In extreme cases, the pulsar’s wind erodes the companion, reducing its mass to a fraction of the Sun’s. Known as “black widows” and “redbacks,” these pulsars imitate destructive spider behaviors towards their companions. However, studying these cosmic “spiders” presents challenges. Their observed brightness hinges on the measured distance, shaping our understanding of the interaction between the pulsar wind and the companion star.
Using Gaia space telescope data, our study discloses that Gaia-derived distances of spiders consistently surpass previous estimates based on radio observations—the wavelength typically used to locate pulsars and measure their properties. This discovery yields novel insights. In our Galaxy, redback pulsars are more proficient in generating X-ray radiation than black widows, underscoring the significance of effective shock generation between pulsar wind and the companion star. Furthermore, we have unveiled a connection between optical brightness and orbital periods of these binary systems, implying gravitational distortion of the companion stars that depends on the size of the orbit. This association also offers a means to estimate the optical brightness for newly detected spider systems.
