Overview

• China’s FAST telescope observed a rapidly spinning neutron star stripping its companion star to a helium core, forming a rare 'spider pulsar.'
• The binary system, PSR J1928+1815, has a 3.6-hour orbital period, with the pulsar's radio signals eclipsed by its companion for one-sixth of each orbit.
• The companion star, undetectable outside radio wavelengths, is a hydrogen-stripped helium core roughly as massive as the Sun.
• This discovery offers the first direct confirmation of the long-theorized common envelope evolutionary process in binary star systems.
• Published in Science on May 22, 2025, the findings shed light on the formation of gravitational-wave progenitors and suggest over a dozen similar systems may exist in the Milky Way.