Contents

Astronomy Letters

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Vol. 47, No. 4, 2021

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Annihilation of $\mathbf{{}^{22}}$Na Positrons in Novae

N. N. Chugai and A. D. Kudryashov p. 197  abstract

Opacity of Ejecta in Calculations of Supernova Light Curves

M. Sh. Potashov, S. I. Blinnikov, and E. I. Sorokina p. 204  abstract

Phase-Resolved Spectroscopy of the Magnetar SGR J1745–2900 Based on Data from the NuSTAR Observatory

E. A. Kuznetsova, A. A. Lutovinov, and A. N. Semena p. 214  abstract

Analysis of Selected Runaway Stars in the Orion Nebula Based on Data from the Gaia EDR3 Catalogue

V. V. Bobylev and A. T. Bajkova p. 224  abstract

Spectrophotometric Monitoring of the Activity of the Symbiotic Star CH Cyg from 2008 to 2018

T. N. Tarasova and A. Skopal p. 235  abstract

Changes in the Period of SU Sct, a Population II Cepheid

L. N. Berdnikov and E. N. Pastukhova p. 252  abstract

Three-Dimensional Version of Hill’s Problem with Variable Mass

Ferdous Bouaziz-Kellil p. 262  abstract

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