Research explores the parameters of X-ray binary system Scorpius X-1


Light curves of Sco X-1 in high and low states (and a mean curve) in stellar magnitudes. Credit: Cherepashchuk et al., 2021.

Using knowledge from NASA’s Kepler telescope, Russian astronomers have investigated an X-ray binary referred to as Scorpius X-1 (or Sco X-1 for brief). Results of the research, revealed September 2 on the arXiv pre-print repository, present additional insights into the parameters of this method.

X-ray binaries encompass a traditional star or a white dwarf transferring mass onto a compact neutron star or a black hole. Based on the mass of the companion star, astronomers divide them into low-mass X-ray binaries (LMXBs) and high-mass X-ray binaries (HMXBs).

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Scorpius X-1 was detected in 1962 as the primary compact X-ray supply outdoors the solar system. Located some 9,000 light years away within the constellation Scorpius, Sco X-1 is the strongest obvious supply of X-rays within the sky. The binary consists of an optically seen star V818 Scorpii with a mass of solely 0.42 solar lots, and a neutron star about 40 % extra huge than the sun. Therefore, the system has been categorized as an LMXB.

A gaggle of astronomers from the Lomonosov Moscow State University in Russia, led by Anatol M. Cherepashchuk, determined to research the information from Kepler spacecraft’s extended mission referred to as K2. The predominant goal of the research was to derive parameters of the Sco X-1 system.

“We modeled optical light curves of Sco X-1 obtained by the Kepler space telescope during the K2 mission,” the researchers wrote within the paper.

The mannequin allowed the staff to estimate the mass ratio of the 2 elements of Sco X-1, which was discovered to be round 3.6. According to the research, V818 and the neutron star have lots of about 0.4 and 1.44 solar lots, respectively. The system’s orbital inclination seems to be between 25 and 34 levels.

The analysis discovered that V818 has a radius of some 1.25 solar radii and bolometric luminosity at a stage of 0.21-0.46 decillion erg/s. The star’s temperature is estimated to be between 2,500 and three,050 Ok. The outcomes typically recommend that V818 has a spectral sort M4-M5V.

The astronomers assume that V818 possessed vital excesses of radius and luminosity because it may need moved in its evolutionary method and underwent a big mass loss. They added that its preliminary mass needs to be larger than 0.8 solar lots.

“Probably, the mass of the donor star was reduced due to the mass loss from the system in the stellar wind that was induced by the strong X-ray heating. Another possibility consisted in that the star was not in the thermal equilibrium and had an excess of the radius according to its mass due to the rapid mass loss,” the researchers defined.

The research additionally discovered that through the transition of Sco X-1 from the optical excessive state to the low state the total optical flux from the system dropped by about 35 %. The drop of the typical flux from the donor star was roughly 5 %, and it was about 30 % for the accretion disk’s flux.

OO Dra is an Algol-type binary formed through an extremely helium-poor mass accretion

More info:
A. M. Cherepashchuk, T. S. Khruzina, A. I. Bogomazov, Parameters of X-ray binary system Scorpius X-1. arXiv:2109.00967 [astro-ph.SR],

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Research explores the parameters of X-ray binary system Scorpius X-1 (2021, September 13)
retrieved 13 September 2021

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