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<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ali="http://www.niso.org/schemas/ali/1.0/" article-type="research-article" dtd-version="1.2" xml:lang="en"><front><journal-meta><journal-id journal-id-type="publisher-id">Astronomy Reports</journal-id><journal-title-group><journal-title xml:lang="en">Astronomy Reports</journal-title><trans-title-group xml:lang="ru"><trans-title>Астрономический журнал</trans-title></trans-title-group></journal-title-group><issn publication-format="print">0004-6299</issn><issn publication-format="electronic">3034-5170</issn><publisher><publisher-name xml:lang="en">The Russian Academy of Sciences</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="publisher-id">647580</article-id><article-id pub-id-type="doi">10.31857/S0004629924010024</article-id><article-id pub-id-type="edn">LFVSED</article-id><article-categories><subj-group subj-group-type="toc-heading" xml:lang="en"><subject>Articles</subject></subj-group><subj-group subj-group-type="toc-heading" xml:lang="ru"><subject>СТАТЬИ</subject></subj-group><subj-group subj-group-type="article-type"><subject>Research Article</subject></subj-group></article-categories><title-group><article-title xml:lang="en">Orbital Period Variations of the Eclipsing Binaries RW Cap, BG Peg, and CU Peg</article-title><trans-title-group xml:lang="ru"><trans-title>Изменения орбитальных периодов затменно-двойных систем RW Cap, BG Peg и CU Peg</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author"><name-alternatives><name xml:lang="en"><surname>Khaliullina</surname><given-names>A. I.</given-names></name><name xml:lang="ru"><surname>Халиуллина</surname><given-names>А. И.</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><email>hfh@sai.msu.ru</email><xref ref-type="aff" rid="aff1"/></contrib></contrib-group><aff-alternatives id="aff1"><aff><institution xml:lang="en">Sternberg Astronomical Institute, Moscow State University</institution></aff><aff><institution xml:lang="ru">Государственный астрономический институт им. П. К. Штернберга МГУ им. М. В. Ломоносова</institution></aff></aff-alternatives><pub-date date-type="pub" iso-8601-date="2024-01-15" publication-format="electronic"><day>15</day><month>01</month><year>2024</year></pub-date><volume>101</volume><issue>1</issue><issue-title xml:lang="ru"/><fpage>12</fpage><lpage>24</lpage><history><date date-type="received" iso-8601-date="2025-01-28"><day>28</day><month>01</month><year>2025</year></date></history><permissions><copyright-statement xml:lang="en">Copyright ©; 2024, The Russian Academy of Sciences</copyright-statement><copyright-statement xml:lang="ru">Copyright ©; 2024, Российская академия наук</copyright-statement><copyright-year>2024</copyright-year><copyright-holder xml:lang="en">The Russian Academy of Sciences</copyright-holder><copyright-holder xml:lang="ru">Российская академия наук</copyright-holder></permissions><self-uri xlink:href="https://journals.eco-vector.com/0004-6299/article/view/647580">https://journals.eco-vector.com/0004-6299/article/view/647580</self-uri><abstract xml:lang="en"><p>The variations in the orbital period of the eclipsing binaries RW Cap, BG Peg, and CU Peg have been analyzed. The variations in the period of RW Cap and BG Peg can be well represented by cyclic variations with large amplitude. It has been shown, that these variations cannot be explained by the presence of a third body. They can be a consequence of the magnetic activity of the secondary components having a convective zone. The variations in the period of CU Peg can be represented by a superposition of a secular period increase due to exchange of matter between the components and cyclic variations. These cyclic variations can occur due to the presence of a third body in the system or they can be a consequence of the magnetic activity of the secondary component.</p></abstract><trans-abstract xml:lang="ru"><p>В затменно-двойных системах типа Алголя RW Cap, BG Peg и CU Peg проведено исследование изменений орбитальных периодов. Изменения периодов RW Cap и BG Peg хорошо представляются циклическими колебаниями с большой амплитудой. Показано, что эти изменения нельзя объяснить присутствием третьего тела. Они могут быть следствием магнитной активности вторичных компонентов, имеющих конвективную оболочку. Изменения периода CU Peg можно представить суперпозицией векового изменения за счет обмена веществом между компонентами и циклических изменений, которые могут происходить из-за присутствия в системе третьего тела или быть следствием магнитной активности вторичного компонента.</p></trans-abstract><kwd-group xml:lang="en"><kwd>binary stars</kwd><kwd>eclipsing stars</kwd><kwd>individual — RW Cap</kwd><kwd>BG Peg</kwd><kwd>CU Peg</kwd></kwd-group><kwd-group xml:lang="ru"><kwd>двойные звезды</kwd><kwd>затменные звезды</kwd><kwd>отдельные — RW Cap</kwd><kwd>BG Peg</kwd><kwd>CU Peg</kwd></kwd-group><funding-group/></article-meta></front><body></body><back><ref-list><ref id="B1"><label>1.</label><mixed-citation>D. S. Hall, Space Sci. 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