Stars at this mass range and evolutionary stage are pulsationally unstable, displaying a variation in their light output.[7] R Cygni has a maximum magnitude of 6.1 and a minimum magnitude of 14.4, with a period of 426.45 days.[2] The variation of this star was discovered by English astronomer N. R. Pogson in 1852, and it has a history of recorded brightness measurements stretching back more than a century.[7] R Cygni shows distinct period-doubling, where alternate maxima are of different brightness, hence the real period of pulsation could be considered to be twice that from one maximum to the next.[8]
^ a b c d eBrown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
^ a b cSamus', N. N; Kazarovets, E. V; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N (2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 125853869.
^ a b c dAnders, F.; Khalatyan, A.; Queiroz, A. B. A.; Chiappini, C.; Ardevol, J.; Casamiquela, L.; Figueras, F.; Jimenez-Arranz, O.; Jordi, C.; Monguio, M.; Romero-Gomez, M.; Altamirano, D.; Antoja, T.; Assaad, R.; Cantat-Gaudin, T.; Castro-Ginard, A.; Enke, H.; Girardi, L.; Guiglion, G.; Khan, S.; Luri, X.; Miglio, A.; Minchev, I.; Ramos, P.; Santiago, B. X.; Steinmetz, M. (2022). "VizieR Online Data Catalog: StarHorse2, Gaia EDR3 photo-astrometric distances (Anders+, 2022)". Vizier Online Data Catalog. Bibcode:2022yCat.1354....0A.
^Guandalini, R; Francis, Charles (2010). "Infrared photometry and evolution of mass-losing AGB stars. III. Mass loss rates of MS and S stars". Astronomy and Astrophysics. 513: A4. arXiv:1002.2458. Bibcode:2010A&A...513A...4G. doi:10.1051/0004-6361/200911764. S2CID 119193286.
^ a bKiss, L. L.; Szatmáry, K. (August 2002). "Period-doubling events in the light curve of R Cygni: Evidence for chaotic behaviour". Astronomy and Astrophysics. 390 (2): 585–596. arXiv:astro-ph/0205334. Bibcode:2002A&A...390..585K. doi:10.1051/0004-6361:20020744. S2CID 17698877.
^Kiss, L. L; Szatmáry, K (2002). "Period-doubling events in the light curve of R Cygni: Evidence for chaotic behaviour". Astronomy & Astrophysics. 390 (2): 585–596. arXiv:astro-ph/0205334. Bibcode:2002A&A...390..585K. doi:10.1051/0004-6361:20020744. S2CID 17698877.
^Mason, Brian D; Wycoff, Gary L; Hartkopf, William I; Douglass, Geoffrey G; Worley, Charles E (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.