Science

Unusual double X-ray star discovered

12:17 31.03.2023 Science

Astronomers have discovered the unusual X-ray binary star XTE J17390-285 during a burst of activity using the AstroSat and NuSTAR space telescopes. The results of the study are published in the arXiv preprint repository.

X-ray binaries (XRBs) consist of an ordinary star or white dwarf transferring mass to a compact neutron star or black hole. Based on the mass of the companion star, astronomers divide X-ray binaries into low-mass X-ray binaries (LMXB) and high-mass X-ray binaries (HMXB).

Some LMXBs exhibit short bursts of increasing X-ray luminosity. Type I X-ray bursts occur in binary systems that neutron stars have, and are thermonuclear explosions that occur in the surface layers of neutron stars.

X-ray light curves from observations of XTE J1739-285 made in 2019 indicate the presence of outbursts due to the tug of the companion star's matter. In addition, observations have revealed accretion-induced X-ray pulsations at 386 hertz over very short intervals (0.5 to 1 second), making XTE J1739-285 a discontinuous X-ray pulsar.

AstroSat observations of XTE J1739-285 in 2020 revealed the presence of an X-ray fusion burst. Thus, XTE J1739-285 turns out to be one of the few LMXB neutron stars experiencing both nuclear and accretionary pulsations.

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