This star was found to be variable by H. K. Gitz in 1936 based on photographic plates taken in Moscow, then S. Kaho published an ephemeris in 1939 using observed minima.[9] In 1950, O. Struve computed the orbital elements for a single-lined spectroscopic binary system with a short orbital period of just 17 hours. He found a stellar classification of A0V for the primary component.[10]P. Broglia and P. Conconi analyzed the light curve of the system in 1977, and determined this to be a semidetached binary with the secondary component being significantly less massive than the primary.[11] In 1996, V. Simon found a periodic variation in the system minima with a cycle length of 22 years. He proposed that this variation is being driven by a third component in the system.[9]
The light-travel time effect provides information about the properties of the purported third component in the system. It has 0.787 times the mass of the Sun and is orbiting at a distance of 10.75 AU from the inner pair with an eccentricity of 0.35 and a period of 23.22±0.17 years.[13]
^ abcLucy, L. B.; Sweeney, M. A. (August 1971), "Spectroscopic binaries with circular orbits", Astronomical Journal, 76: 544–556, Bibcode:1971AJ.....76..544L, doi:10.1086/111159.
See row 19, table 1, p. 540.
^ abŠimon, V. (July 1996), "The cyclic period changes of the close binary VV Ursae Majoris", Astronomy and Astrophysics, 311: 915–918, Bibcode:1996A&A...311..915S.
^Struve, Otto (July 1950), "Spectrographic Observations of the Eclipsing Binaries TW Cassiopeiae, TY Puppis, and VV Ursae Majoris", Astrophysical Journal, 112: 184, Bibcode:1950ApJ...112..184S, doi:10.1086/145326.
^ abBroglia, P.; Conconi, P. (February 1977), "Two-colour photometry and elements of VV UMa", Astronomy and Astrophysics Supplement Series, 27: 285–293, Bibcode:1977A&AS...27..285B.
^Gunsriwiwat, K.; Mkrtichian, D. E. (September 2015), "Study of Pulsation Spectrum of Mass-accreting Component of Algol-type system VV UMa", Information Bulletin on Variable Stars, 6148: 1, Bibcode:2015IBVS.6148....1G.
^Tanrıver, Mehmet (April 2015), "Cyclic period changes and the light-time effect in eclipsing binaries: A low-mass companion around the system VV Ursae Majoris", New Astronomy, 36: 56–63, Bibcode:2015NewA...36...56T, doi:10.1016/j.newast.2014.09.008.
Further reading
Ulas, Burak; et al. (August 2007), "The Algol-type Binary VV UMa: New VRI Photometry and Search for Pulsations", JENAM-2007, "Our non-stable Universe", held 20–25 August 2007 in Yerevan, Armenia, p. 21, Bibcode:2007jena.confE..21U, 21-21.
Kim, S. -L.; et al. (February 2005), "On a short-periodic pulsating component in the Algol-type eclipsing binary system VV UMa", Information Bulletin on Variable Stars, 5598: 1, Bibcode:2005IBVS.5598....1K.
Simon, Vojtech (1997), Leung, Kam-Ching (ed.), "Period Changes of the Binary VV UMa: Light-Time Effect or Magnetic Activity", The Third Pacific Rim Conference on Recent Development on Binary Star Research. Proceedings of a conference sponsored by Chiang Mai University, Thai Astronomical Society and the University of Nebraska-Lincoln held in Chiang Mai, Thailand, 26 October -1 November 1995, ASP Conference Series, vol. 130, p. 277, Bibcode:1997ASPC..130..277S.
Simon, V. (July 1996), "The cyclic period changes of the close binary VV Ursae Majoris", Astronomy and Astrophysics, 311: 915–918, Bibcode:1996A&A...311..915S.
Wunder, E. (March 1995), "The First Period Change Discovered in the Bright Algol System UV Leonis", Information Bulletin on Variable Stars, 4179: 1, Bibcode:1995IBVS.4179....1W.
Horák, T. (1966), "New elements of the eclipsing variables TW Draconis, RW Tauri and KR Cygni and the influence of the rectification of the light curve upon the elements VV Ursae Maioris", Bulletin of the Astronomical Institute of Czechoslovakia, 17: 272, Bibcode:1966BAICz..17..272H.
Wilson, Robert E. (June 1965), "A possible extended atmosphere in the eclipsing system W UMa", Astronomical Journal, 70: 368, Bibcode:1965AJ.....70..368W, doi:10.1086/109749.