BC Cygni

BC Cygni
BC Cygni is visible as a red star (circled). 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 38.55s[1]
Declination 37° 31′ 58.9″[1]
Apparent magnitude (V) 9.0 - 10.8[2]
Characteristics
Spectral type M3.5 Ia[3] (M2 - M5[4])
B−V color index +3.13 - +3.21[4]
Variable type SRc[3]
Astrometry
Radial velocity (Rv)−20.97[1] km/s
Proper motion (μ) RA: −3.710 mas/yr[1]
Dec.: −6.307 mas/yr[1]
Parallax (π)0.5760 ± 0.0500 mas[1]
Distance5,418+470
−430 ly
(1,662+144
−132 pc)[5]
Absolute magnitude (MV)−7.71[6]
Details
Mass19[4][7] M☉
Radius1,031[7][a] R☉
Luminosity150,000[7]
204,000+159,000
−56,000[8] L☉
Temperature3,535[7] K
Age>9[7][b] Myr
Other designations
BC Cyg, HIP 100404, HV 3339, BD+37°3903, IRAS 20197+3722, 2MASS J20213855+3731589
Database references
SIMBADdata

BC Cygni (BC Cyg, HIP 100404, BD + 37 3903) is a red supergiant and pulsating variable star of spectral type M3.5Ia in the constellation Cygnus.

It is considered a member of the stellar Cygnus OB1 association, and within it the open cluster Berkeley 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 found to have a luminosity of 145,000 L☉ and an effective temperature of 2,858 K in the year 1900, and a luminosity of 112,000  L☉ and a temperature of 3,614 K in the year 2000. At its brightest and coolest has been calculated to be 1,553 R☉ compared to 856 R☉ at the hottest and faintest.[11] It is one of largest stars known, and currently is 1,031 times larger than the Sun.[7][a] If it were in the place of the Sun, its photosphere would engulf the entire inner solar system and reach close to the orbit of Jupiter. 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 3.2×10−9 M☉ per year.[12]

A visual band light curve for BC Cygni, from AAVSO data[13]

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]

  1. ^ a b c d e f 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. ^ a b 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.
  3. ^ a b 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.
  4. ^ a b c d Turner, David G.; Rohanizadegan, Mina; Berdnikov, Leonid N.; Pastukhova, Elena N. (2006). "The Long-Term Behavior of the Semiregular M Supergiant Variable BC Cygni". The Publications of the Astronomical Society of the Pacific. 118 (849): 1533. Bibcode:2006PASP..118.1533T. doi:10.1086/508905.
  5. ^ Bailer-Jones, C. A. L.; Rybizki, J.; Fouesneau, M.; Demleitner, M.; Andrae, R. (2021-03-01). "Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3". The Astronomical Journal. 161 (3): 147. arXiv:2012.05220. Bibcode:2021AJ....161..147B. doi:10.3847/1538-3881/abd806. ISSN 0004-6256. Data about this star can be seen here.
  6. ^ Levesque, Emily M.; Massey, Philip; Olsen, K. A. G.; Plez, Bertrand; Josselin, Eric; Maeder, Andre; Meynet, Georges (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.
  7. ^ a b c d e f 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.
  8. ^ Davies, Ben; Beasor, Emma R. (March 2020). "The 'red supergiant problem': the upper luminosity boundary of Type II supernova progenitors". MNRAS. 493 (1): 468–476. arXiv:2001.06020. Bibcode:2020MNRAS.493..468D. doi:10.1093/mnras/staa174. S2CID 210714093.
  9. ^ Sokal, Kimberly R.; Skinner, Stephen L.; Zhekov, Svetozar A.; Güdel, Manuel; Schmutz, Werner (2010). "Chandra Detects the Rare Oxygen-type Wolf-Rayet Star WR 142 and OB Stars in Berkeley 87". The Astrophysical Journal. 715 (2): 1327. arXiv:1004.0462. Bibcode:2010ApJ...715.1327S. doi:10.1088/0004-637X/715/2/1327. S2CID 119232391.
  10. ^ 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. S2CID 232170603.
  11. ^ Turner, David G.; Rohanizadegan, Mina; Berdnikov, Leonid N.; Pastukhova, Elena N. (2006-11-02). "The Long-Term Behavior of the Semiregular M Supergiant Variable BC Cygni". Publications of the Astronomical Society of the Pacific. 118 (849): 1533. Bibcode:2006PASP..118.1533T. doi:10.1086/508905. ISSN 1538-3873.
  12. ^ Josselin, E.; Plez, B. (2007). "Atmospheric dynamics and the mass loss process in red supergiant stars". Astronomy and Astrophysics. 469 (2): 671. arXiv:0705.0266. Bibcode:2007A&A...469..671J. doi:10.1051/0004-6361:20066353. S2CID 17789027.
  13. ^ Cite error: The named reference aavso was invoked but never defined (see the help page).


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