BI Cygni
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  Credit: Erik Larsen | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 20h 21m 21.8803s[1] |
| Declination | 36° 55′ 55.771″[1] |
| Apparent magnitude (V) | 8.4 - 9.9[2] |
| Characteristics | |
| Spectral type | M4 Iab[2] |
| Variable type | Lc[2] |
| Astrometry | |
| Proper motion (μ) | RA: −2.929±0.140[3] mas/yr Dec.: −5.223±0.151[3] mas/yr |
| Parallax (π) | 0.7269 ± 0.0811[3] mas |
| Distance | 1,580[4] pc |
| Absolute magnitude (MV) | −6.78[5] |
| Details | |
| Radius | 850[6] - 1,240[5] R☉ |
| Diameter | 850[6] - 1,240[5] D☉ |
| Luminosity | 123,000[4]-226,000[5] L☉ |
| Temperature | 3,575[5][4]-3,720[6] K |
| Database references | |
| SIMBAD | data |
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 has a current mass of 20 M☉.[6]
It is considered a member of the stellar Cygnus OB1 association,[5] its distance is 1,580 parsecs (5,150 light-years) of the Solar System. It is less than a degree south of another variable red supergiant, BC Cygni.
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.[7]
BI Cyg is one of largest known stars with a radius around 1,240 D☉ based on the assumption of an effective temperature of 3,575 K and a bolometric luminosity of 226,000 L☉.[5] More recent studies derive lower luminosities below 130,000 L☉, suggesting an initial mass of 20 M☉, and consequently lower values for the radius.[4][6]
See also[edit]
References[edit]
- ↑ 1.0 1.1 Hog, E.; Kuzmin, A.; Bastian, U.; Fabricius, C.; Kuimov, K.; Lindegren, L.; Makarov, V. V.; Roeser, S. (1998). "The TYCHO Reference Catalogue". Astronomy and Astrophysics 335: L65. Bibcode 1998A&A...335L..65H.
- ↑ 2.0 2.1 2.2 2.3 Samus, N. N.Expression error: Unrecognized word "etal". (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.
- ↑ 3.0 3.1 3.2 Brown, A. G. A. (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.
- ↑ 4.0 4.1 4.2 4.3 Nicolas Mauron; Eric Josselin (2010). "The mass-loss rates of red supergiants and the de Jager prescription". Astronomy and Astrophysics 526: A156. arXiv:1010.5369. Bibcode 2011A&A...526A.156M. doi:10.1051/0004-6361/201013993.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Table 4 in Levesque, Emily M.; Massey, Philip; Olsen, K. A. G.; Plez, Bertrand; Josselin, Eric; Maeder, Andre; Meynet, Georges (August 2005). "The Effective Temperature Scale of Galactic Red Supergiants: Cool, but Not As Cool As We Thought". The Astrophysical Journal 628 (2): 973–985. arXiv:astro-ph/0504337. Bibcode 2005ApJ...628..973L. doi:10.1086/430901.
- ↑ 6.0 6.1 6.2 6.3 Josselin, E.; Plez, B. (2007). "Atmospheric dynamics and the mass loss process in red supergiant stars". Astronomy and Astrophysics 469 (2): 671–680. arXiv:0705.0266. Bibcode 2007A&A...469..671J. doi:10.1051/0004-6361:20066353.
- ↑ Kiss, L. L; Szabó, Gy. M; Bedding, T. R (2006). "Variability in red supergiant stars: Pulsations, long secondary periods and convection noise". Monthly Notices of the Royal Astronomical Society 372 (4): 1721. arXiv:astro-ph/0608438. Bibcode 2006MNRAS.372.1721K. doi:10.1111/j.1365-2966.2006.10973.x.
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