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      https://www.ias.ac.in/article/fulltext/joaa/009/04/0213-0224

    • Keywords

       

      spectroscopic binaries; RS CVn stars; stars, individual

    • Abstract

       

      HD 115781 and HD 116204 (BL CVn and BM CVn) are shown to be RS CVn binaries with periods near 20 days. HD 115781 is double-lined; the primary type is about K1III, while the secondary is probably a late-type subgiant. The masses of the two components are equal within observational error. There is substantial photometric variability with a period half the orbital period; it is attributed to ellipsoidal variation. HD 116204 is also of type K1III. It shows exceptionally strong Ca II H and K emission, together with an emission-line spectrum typical of RS CVn stars in theIUE ultraviolet region, but Hα is an absorption line. The secondary star in the HD 116204 system has not been detected. The primary shows photometric variations, presumably due to starspots, with a period 5 per cent longer than the orbital period.

    • Author Affiliations

       

      R. F. Griffin1 2 3 4 Francis C. Fekel5 6 7

      1. The Observatories, Madingley Road, Cambridge - CB3 0HA, England
      2. Palomar Observatory, USA
      3. Mount Wilson & Las Campanas Observatories, Carnegie Institution of Washington, USA
      4. Dominion Astrophysical Observatory, Victoria
      5. Dyer Observatory, Vanderbilt University, Nashville, Tennessee - 37235, USA
      6. Kitt Peak National Observatory, [U.S.] National Optical Astronomy Observatories, Association of Universities for Research in Astronomy, Inc., [U.S.] National Science Foundation, USA
      7. International Ultraviolet Explorer satellite, USA
    • Dates

       
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