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Pulsations of the AS Cam Eclipsing Binary in TESS Light Curves

Abstract

An analysis of TESS satellite observations of the AS Cam eclipsing binary has shown that the light of this source pulsates at two frequencies: \({{\nu }_{1}} = 0.7556\) days–1 and \({{\nu }_{2}} = 0.8658\) days–1 with the amplitudes \({{A}_{1}} = 0_{.}^{{\text{m}}}0110\) and \({{A}_{2}} = 0_{.}^{{\text{m}}}0087,\) correspondingly. Such variations are typical for slowly pulsating B-type stars. We modeled the light curves of AS Cam obtained from 1968 to 2019 to confirm the discovery of a gradual increase in the orbit eccentricity of the system by approximately 0.018 over 50 years. A third light, as one of the light curve solution parameters, on average, amounts to approximately 4% of the total luminosity of the system. For AS Cam this would correspond to an F8–F9-type suggested third body—a main sequence star, the presence of which follows from the light equation of the system. If the third light is a result of a random overlapping of a star unrelated to AS Cam, then the third body may turn out to be a degenerate object or a close binary system. The extremely slow apsidal motion in this system (compared to the value predicted by the standard theory) can be explained by the gravitational influence of a third body with a mass of about \(1.2{{M}_{ \odot }}\) and an orbital inclination of about \(70\) with respect to the image plane.

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Notes

  1. See the B.R.N.O. database, http://var2.astro.cz/ocgate/?lang=en.

  2. https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html.

  3. Exotic alternatives like a revision of the gravity theory are not mentioned. The general theory of relativity gives estimates of the apsidal line rotation velocity that coincide practically ideally with the observed values for most systems (Baroch et al., 2021), with the exception of a few, AS Cam included.

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ACKNOWLEDGMENTS

This research has made use of the SIMBAD database (operated at CDS, Strasbourg, France) and of NASA’s Astrophysics Data System. Some of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST). The authors are grateful to the anonymous referee for comments that helped improve the paper.

Funding

This research is funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (project no. AP09259383).

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Correspondence to V. S. Kozyreva.

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Translated by E. Chmyreva

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Kozyreva, V.S., Kusakin, A.V., Bogomazov, A.I. et al. Pulsations of the AS Cam Eclipsing Binary in TESS Light Curves. Astrophys. Bull. 76, 424–434 (2021). https://doi.org/10.1134/S1990341321040088

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  • DOI: https://doi.org/10.1134/S1990341321040088

Keywords:

  • stars: binaries: eclipsing
  • stars: individual: AS Cam