Superdense neutron star caught feeding on a blue hypergiant's stellar wind

Astronomers using the XRISM observatory have directly observed a blue hypergiant star's stellar wind being captured by a superdense neutron star, providing the power source for strong X-ray flares. The study, published in Science Advances, details the process of a pulsar's gravitational influence on the star, creating a dense plasma stream. The research highlights the neutron star, GX 301-2, which is about 12 miles in diameter and rotates every 11 minutes, sweeping an X-ray beam toward Earth. The pulsar's orbit around the primary star, a blue hypergiant, lasts about 41.5 days, with flares occurring twice during the closest and farthest points. The observations show the plasma moving toward the pulsar at approximately 335,000 mph, revealing the pulsar's role in capturing the stellar wind.

The study's key findings include the detection of highly ionized iron absorption lines, indicating the speed and direction of the plasma close to the pulsar. These lines, captured by the Resolve instrument on the NASA-JAXA XRISM observatory, show a redshift, suggesting the gas is flowing toward the neutron star. The research confirms the pulsar's ability to capture the dense stream of plasma, forming a turbulent accretion disk that eventually breaks up, allowing the plasma to fall directly onto the neutron star. The observations provide a detailed understanding of how such processes occur, offering insights into the mechanisms of accretion in extreme astrophysical environments.

The study underscores the importance of the BP Crucis system as a laboratory for studying wind-fed pulsar accretion. The XRISM observatory's high-resolution spectrometer, the Resolve instrument, played a crucial role in capturing the detailed spectral data. The findings contribute to the broader understanding of stellar wind dynamics and the role of compact objects in cosmic phenomena. The research highlights the significance of such observations in advancing our knowledge of the extreme universe.

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