Tau Cygni, Latinised from τ Cygni, is a binary star system in the constellation Cygnus, approximately 69 light years away from Earth.[4] This visual binary system has a period of 49.6 years.[2]
The main star, 4th magnitude GJ 822.1 A, is a yellowish white subgiant star of the spectral type F2IV. It therefore has a surface temperature of 6,000 to 7,500 kelvins and is larger, hotter, and several times as bright as the Sun.[5] Its companion, 6th magnitude GJ 822.1 B, is a yellow main sequence star of the spectral type G0V. It is similar to the Sun in size, surface temperature, and luminosity.[6]
Tau Cygni is classified as a δ Scuti variable. The magnitude range is given as 3.65 to 3.75, which is the combined magnitude for both components, although the variable component is A.[1]
References
^ abcSamus, 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.