BI Cygni (BI Cyg, IRC +40408, BD+36 4025) is a red supergiant in the constellation Cygnus. It is an irregular variable star with a maximum brightness of magnitude 8.4 and a minimum of magnitude 9.9. It is considered a member of the Cygnus OB1 stellar association,[4] its distance is around 1,300 parsecs (4,200 ly) of the Solar System. It is less than a degree south of another variable red supergiant, BC Cygni.
BI Cygni is the small very red dot right on the left edge of this image. The bright star at the centre is γ Cygni and north is to the right. Credit: Erik Larsen | |
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Cygnus |
Right ascension | 20h 21m 21.8869s[1] |
Declination | 36° 55′ 55.729″[1] |
Apparent magnitude (V) | 8.4 – 9.9[2] |
Characteristics | |
Evolutionary stage | Red supergiant |
Spectral type | M4 Iab[2] |
Variable type | Lc[2] |
Astrometry | |
Radial velocity (Rv) | −7.48±0.42[1] km/s |
Proper motion (μ) | RA: −2.751[1] mas/yr Dec.: −5.459[1] mas/yr |
Parallax (π) | 0.3541 ± 0.0377 mas[1] |
Distance | 4,349+548 −440 ly (1,334+168 −135 pc)[3] |
Absolute magnitude (MV) | −6.78[4] |
Details | |
Mass | 17[5] M☉ |
Radius | 852+12 −9 – 908+12 −10[3] R☉ |
Luminosity | 89,300[5] L☉ |
Surface gravity (log g) | -0.35[6] cgs |
Temperature | 3,575[3][5] K |
Metallicity [Fe/H] | +0.40[6] dex |
Age | >12[5] Myr |
Other designations | |
Database references | |
SIMBAD | data |
BI Cyg is a slow irregular variable star classified as type Lc, an irregular supergiant. Its brightness changes between extremes of magnitude 8.4 and 9.9.[2] Frequency analysis of its light curve shows no significant periods.[8]
BI Cyg is one of the largest known stars with a radius around 850 R☉, measured by its angular diameter by the CHARA array.[3] It is about 90,000 times more luminous that the Sun and has a cool effective temperature of 3,535 K.[5] Its mass is estimated at 17 solar masses, and it took 12 million years to enter the red supergiant phase.[5]
See also
Notes
References
External links
Wikiwand in your browser!
Seamless Wikipedia browsing. On steroids.
Every time you click a link to Wikipedia, Wiktionary or Wikiquote in your browser's search results, it will show the modern Wikiwand interface.
Wikiwand extension is a five stars, simple, with minimum permission required to keep your browsing private, safe and transparent.