J/A+A/454/295ivo://CDS.VizieR/J/A+A/454/295doi:10.26093/cds/vizier.34540295CDSFroehlich H.-E.Kroll P.Strassmeier K.G.2017-06-29T08:55:37Z2006-12-20T15:57:19ZCDS support team

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

cds-question@unistra.frlate-type-starsvisible-astronomyphotographic-photometryphotometric-systemsLong-term photographic photometry of the active long-period RS CVn binary HK Lac (HD 209813) was obtained from more than 2000 Sonneberg Sky-Patrol plates taken between 1956 and 1996. We achieve an internal accuracy of 0.07mag. The correspondence with contemporaneous high-precision photoelectric photometry from automatic telescopes is striking and successfully demonstrates the feasibility of our approach. Based on a Bayesian periodogram analysis, we improve previously published cycle periods to 13.37+/-0.8 and 6.7+/-0.1-years, and present evidence of an additional period of 9.48+/-0.13-years. This establishes the multi-periodicity of dynamo action in these overactive stars as compared to the Sun. Of course, the 6.7-years cycle may be an overtone of the dominating 13.4-years cycle. Our long-term photographic photometry even allowed the detection of the star's mean rotational period of 24.35-days.2006A&A...454..295Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/454/295CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/454/295https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/454/295http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/454/295https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/454/295https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/454/295http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/454/295GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/454/295/table1Julian Date and BT magnituderecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJDGeocentric Julian Date at the middle of the exposuretime.epochdoubleBTmagBT brightness in the tycho-2 system (1)magphot.mag;em.opt.Bfloat