Arachnid astrometry: Charting the distances to celestial spiders with Gaia

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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”…

The power of irradiation: How vicious can spider pulsars be?

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We present the first multi-band optical light curves of PSR J1622-0315, among the most compact known redback binary millisecond pulsars, with an orbital period Porb=3.9 h. We find a flux modulation with two maxima per orbital cycle and a peak-to-peak amplitude of about 0.3 mag, which we attribute to the ellipsoidal shape of the tidally distorted companion star. The optical colours imply a late-F to early-G spectral type companion and do not show any detectable temperature changes along the orbit. This suggests that the irradiation of the star’s inner face by the pulsar wind is unexpectedly missing despite its short orbital period.