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On the Nature of the 35-Day Cycle in HZ Her/Her X-1

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Abstract

Regular variations of the pulse period of Her X-1 with X-ray flux observed by Fermi/GBM are examined. We argue that these regular variations result from free precession of the neutron star in Her X-1.

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Notes

  1. https://gammaray.nsstc.nasa.gov/gbm/science/pulsars/lightcurves/herx1.html

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ACKNOWLEDGMENTS

The authors acknowledge Drs. M.R. Gilfanov and S.V. Molkov for drawing attention to the Fermi/GBM observations of Her X-1.

Funding

The research is supported by the RFBR grant no. 18-502-12025 and the Interdisciplinary Scientific and Educational School of Moscow University “Fundamental and Applied Space Research.”

Author information

Authors and Affiliations

  1. Sternberg Astronomical Institute, Moscow State University, 119234, Moscow, Russia

    N. I. Shakura, D. A. Kolesnikov & K. A. Postnov

  2. Kazan Federal University, 420008, Kazan, Russia

    N. I. Shakura & K. A. Postnov

Authors
  1. N. I. Shakura
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  2. D. A. Kolesnikov
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  3. K. A. Postnov
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Corresponding author

Correspondence to D. A. Kolesnikov.

Additional information

Paper presented at the Fourth Zeldovich meeting, an international conference in honor of Ya.B. Zeldovich held in Minsk, Belarus, on September 7–11, 2020. Published by the recommendation of the special editors: S.Ya. Kilin, R. Ruffini, and G.V. Vereshchagin.

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Shakura, N.I., Kolesnikov, D.A. & Postnov, K.A. On the Nature of the 35-Day Cycle in HZ Her/Her X-1. Astron. Rep. 65, 1039–1041 (2021). https://doi.org/10.1134/S1063772921100334

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