This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Pulsars are rapidly rotating neutron stars, the extremely dense cores left behind when massive stars explode. Astrophysicists have recently observed a pulsar rotating over 300 times per second that appeared to be slowing down unusually quickly.
Studies suggested that this pulsar's apparent slowdown could be linked to the gravitational pull of another star. Ultimately, its rotation offered clues about a rare system of three stars orbiting together. Researchers at the National Astronomical Observatories of the Chinese Academy of Sciences and other institutions recently investigated this pulsar, called PSR J0435+3233, and its companion stars.
Their paper, published in The Astrophysical Journal Letters, identifies a close pair consisting of the pulsar and a white dwarf, accompanied by a sunlike star in a much wider orbit. The newly identified system could help astronomers to understand how three stars can remain gravitationally bound through the explosion that transforms one of them into a neutron star. Pulsars emit beams of electromagnetic radiation that sweep through space as they rotate, producing detectable pulses when the beams sweep across Earth.
The pulses originating from PSR J0435+3233 arrive approximately 3.2 milliseconds apart, and examining them allows astronomers to track its rotation. J0435+3233 was found to be in orbit with another type of stellar remnant known as a helium white dwarf. Together, these two remnants complete an almost circular orbit every eight days.
To investigate the system, the researchers reprocessed 192 observing sessions from China's Five-hundred-meter Aperture Spherical radio Telescope, known as FAST, spanning nearly five years. Changes in both the observed pulse frequency and the inner pair's orbital frequency pointed to an external acceleration shared by the two stellar remnants. Motion toward or away from Earth changes the spacing of arriving pulses via the so-called Doppler effect.
If the pulsar accelerates away from Earth, the intervals between pulses become longer, making its rotation appear to slow more rapidly than it actually does. By analyzing archived optical and infrared observations, the team identified the likely source of this gravitational influence: a star that is very close to the pulsar's position in the sky and moves similarly across the sky. The researchers interpreted its properties as those of a sunlike star beginning to evolve beyond its main hydrogen-burning stage.
Extract — continue reading at the source.
