J/AJ/107/1868ivo://CDS.VizieR/J/AJ/107/1868doi:10.26093/cds/vizier.51071868CDSBERRINGTON R.C.HALL D.S.2023-04-06T16:50:06Z1997-12-09T20:16:38ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.freclipsing-binary-starsTimings of primary eclipse up through 1992 are collected, plus a few overlooked in earlier studies. Analysis shows that, after decreasing until ~1919 and increasing since then, the period has now started decreasing again, with the inflection point of the O-C curve being ~1972. The shortest period was 4.5727 days, the longest 4.5732 days, with a full cycle length of 96 yr. Explanation by the time-delay effect, due to orbital motion around a third body, would require an unseen black hole companion of >=10M_{sun}_. A magnetic cycle operating in the K-type subgiant, an active dynamo star because of its convection and rapid rotation, is the best explanation. Addresses: Berrington R.C. & Hall D.S. hallxxds@crtvax.vanderbilt.edu Dyer Observatory, Vanderbilt University, Nashville, Tennesee 372351994AJ....107.1868Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/107/1868CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/107/1868https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/107/1868http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/107/1868https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/107/1868https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/107/1868http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/107/1868GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/AJ/107/1868/table1Times of primary minimum for SW CygnirecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintCycleCycle numbermeta.number;time.periodintO-CO-C curve valuedstat.fit.omc;timefloatO-C'O-C' curve valuedstat.fit.omc;timefloatJDJulian datedtime.epochdoubleError[]? Uncertainty or error in original sourcedstat.errorfloatn_ErrorWeights assigned by Slovochotova (1954)meta.notecharRefReference (1)meta.refint