29 Cygni is listed in multiple star catalogs as having several companions within 4′, including the yellow 7th magnitude HD 192661. All are background objects not physically associated with 29 Cygni itself.[15][16] The naked-eye stars b1 Cygni and b2 Cygni, respectively about one and two degrees away, also lie at different distances to 29 Cygni.
Planetary system
In 2022, a superjovian extrasolar planet HIP 99770 b was discovered by direct imaging and astrometry. Its spectral class is between L7 and L9.5, corresponding to a surface temperature of 1400±100 K.[17]
^Samus, N. N.; Durlevich, O. V.; et al. (2009), "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)", VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S, 1: B/gcvs, Bibcode:2009yCat....102025S.
^ abCowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
^Mkrtichian, D. E.; et al. (October 2007), "Multimode Pulsations of the λ Bootis Star 29 Cygni: The 1995 and 1996 Multisite Campaigns", The Astronomical Journal, 134 (4): 1713, Bibcode:2007AJ....134.1713M, doi:10.1086/521434.
^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.
^ abCurrie, Thayne; et al. (2023), "Direct imaging and astrometric detection of a gas giant planet orbiting an accelerating star", Science, 380 (6641): 198–203, arXiv:2212.00034, doi:10.1126/science.abo6192, PMID37053312