BI Cygni

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BI Cygni
Sadr Region rgb.jpg
Red circle.svg
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 [3]
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) [4]
Absolute magnitude  (MV)−6.78 [3]
Details
Mass 17 [5]   M☉
Radius 852+12
−9 –908+12
−10 [4]   R☉
Luminosity 89,300 [5]   L☉
Surface gravity (log g)-0.35 [6]   cgs
Temperature 3,575 [4] [5]   K
Metallicity [Fe/H]+0.40 [6]   dex
Age >12 [5]   Myr
Other designations
RAFGL 2559, BI Cyg, BD+36 4025, WDS J20214+3656, TIC 13249363, TYC 2684-522-1, GSC 02684-00522, IRAS 20194+3646, 2MASS J20212192+3655555
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 is considered a member of the Cygnus OB1 stellar association, [3] 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.

Contents

A visual band light curve for BI Cygni, plotted from INTEGRAL OMC data BICygLightCurve.png
A visual band light curve for BI Cygni, plotted from INTEGRAL OMC 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. [4] 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

References

  1. 1 2 3 4 5 6 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  2. 1 2 3 4 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. Bibcode:2009yCat....102025S.
  3. 1 2 3 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. S2CID   15109583.
  4. 1 2 3 4 Norris, Ryan P. (2019). Seeing Stars Like Never Before: A Long-term Interferometric Imaging Survey of Red Supergiants (PDF) (PhD). Georgia State University.
  5. 1 2 3 4 5 6 Comerón, F.; Djupvik, A. A.; Schneider, N.; Pasquali, A. (October 2020). "The historical record of massive star formation in Cygnus". Astronomy & Astrophysics. 2009: A62. arXiv: 2009.12779 . Bibcode:2020A&A...644A..62C. doi:10.1051/0004-6361/202039188. S2CID   221970180.
  6. 1 2 Anders, F.; Khalatyan, A.; Chiappini, C.; Queiroz, A. B.; Santiago, B. X.; Jordi, C.; Girardi, L.; Brown, A. G. A.; Matijevič, G.; Monari, G.; Cantat-Gaudin, T.; Weiler, M.; Khan, S.; Miglio, A.; Carrillo, I.; Romero-Gómez, M.; Minchev, I.; De Jong, R. S.; Antoja, T.; Ramos, P.; Steinmetz, M.; Enke, H. (2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy and Astrophysics. 628: A94. arXiv: 1904.11302 . Bibcode:2019A&A...628A..94A. doi:10.1051/0004-6361/201935765. S2CID   131780028.
  7. ↑ "OMC Archive". OMC Archive. The Astronomical Data Centre at CAB. Retrieved 19 December 2021.
  8. ↑ 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): 1721–1734. arXiv: astro-ph/0608438 . Bibcode:2006MNRAS.372.1721K. doi: 10.1111/j.1365-2966.2006.10973.x . S2CID   5203133.
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