It is considered a member of the stellar Cygnus OB1 association, and within it the
open clusterBerkeley 87,[9] which would place at a distance of 1,673 parsecs (5,000 ly) of the
Solar System;[10] it is less than a degree north of another variable red supergiant,
BI Cygni.[citation needed] According to its
Gaia Data Release 3 parallax, it is at about 1,700 pc.[1]
BC Cygni was calculated to have an effective temperature of 2,858 to 3,614
K and to vary between 112,000 to 145,000 L☉. The size at its brightest and coolest has been calculated to be 1,553 R☉ compared to 856 R☉ at the hottest and faintest. It is
one of largest stars known. If it were in the place of the
Sun, its
photosphere would engulf the orbit of
Jupiter assuming the maximum radius of 1,553 R☉. With a mass of about 19 M☉, it is estimated that the stellar mass loss, as dust, as the atomic and molecular gas could not be evaluators is 3.2×10−9M☉ per year.[11]
The brightness of BC Cyg varies from
visual magnitude +9.0 and +10.8 with a period of 720 ± 40 days.[2] Between around the year 1900 and 2000 appears to have increased its average brightness of 0.5 magnitudes.[4]
^
abSamus, 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.
Bibcode:
2009yCat....102025S.
^de la Fuente, Diego; Román-Zúñiga, Carlos G.; Jiménez-Bailón, Elena; Alves, João; Garcia, Miriam; Venus, Sean (2021). "Clustered star formation toward Berkeley 87/ON2. I. Multiwavelength census and the population overlap problem". Astronomy and Astrophysics. 650: A156.
arXiv:2103.06062.
Bibcode:
2021A&A...650A.156D.
doi:
10.1051/0004-6361/202040065.
S2CID232170603.