Astronomy:BC Cygni

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Short description: Star in the constellation Cygnus
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
Equinox J2000.0]] (ICRS)
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[1] mas/yr
Dec.: −6.307[1] mas/yr
Parallax (π)0.5760 ± 0.0500[1] mas
Distance5,418+470
−430 ly
(1,662+144
−132 pc)
Details
Mass19[4][5] M☉
Radius1,187[1] R☉
Luminosity150,000[5]
204,000+159,000
−56,000[6] L☉
Temperature3,535[5] K
Age>9[5][lower-alpha 1] 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,[7] which would place at a distance of 1,673 parsecs (5,000 ly) of the Solar System;[8] it is less than a degree north of another variable red supergiant, BI Cygni. 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. It is one of largest stars known, at its brightest and coolest calculated to be 1,553 R☉ compared to 856 R☉ at its hottest and faintest.[9] 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.[10]

A visual band light curve for BC Cygni, from AAVSO data[11]

Louisa Wells discovered that the star's brightness varied, based on the examination of 15 photographic plates. That discovery was announced in 1911.[12] It was given its variable star designation, BC Cygni, in 1914.[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]

See also

Notes

  1. ↑ This is only the age at which the star enters the red supergiant phase.

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 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. doi:10.1111/j.1365-2966.2006.10973.x. Bibcode: 2006MNRAS.372.1721K. 
  3. ↑ 3.0 3.1 Samus, N. N. 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. ↑ 4.0 4.1 4.2 4.3 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. doi:10.1086/508905. Bibcode: 2006PASP..118.1533T. 
  5. ↑ 5.0 5.1 5.2 5.3 Comerón, F.; Djupvik, A. A.; Schneider, N.; Pasquali, A. (October 2020). "The historical record of massive star formation in Cygnus". Astronomy & Astrophysics 2009: A62. doi:10.1051/0004-6361/202039188. Bibcode: 2020A&A...644A..62C. 
  6. ↑ Davies, Ben; Beasor, Emma R. (March 2020). "The 'red supergiant problem': the upper luminosity boundary of Type II supernova progenitors" (in en). MNRAS 493 (1): 468–476. doi:10.1093/mnras/staa174. Bibcode: 2020MNRAS.493..468D. 
  7. ↑ 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. doi:10.1088/0004-637X/715/2/1327. Bibcode: 2010ApJ...715.1327S. 
  8. ↑ 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. doi:10.1051/0004-6361/202040065. Bibcode: 2021A&A...650A.156D. 
  9. ↑ 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" (in en). Publications of the Astronomical Society of the Pacific 118 (849): 1533. doi:10.1086/508905. ISSN 1538-3873. Bibcode: 2006PASP..118.1533T. 
  10. ↑ Josselin, E.; Plez, B. (2007). "Atmospheric dynamics and the mass loss process in red supergiant stars". Astronomy and Astrophysics 469 (2): 671. doi:10.1051/0004-6361:20066353. Bibcode: 2007A&A...469..671J. 
  11. ↑ "Download Data". AAVSO. https://www.aavso.org/data-download. 
  12. ↑ Fleming, Williamina; Pickering, Edward C. (September 1911). "Stars Having Peculiar Spectra. 31 New Variable Stars". Harvard College Observatory Circular 167: 1–3. Bibcode: 1911HarCi.167....1F. 
  13. ↑ Dunér, Nils Christofer; Hartwig, Ernst; Müller, G. (September 1914). "Benennung von neu entdeckten veränderlichen Sternen". Astronomische Nachrichten 199 (5): 65–88. doi:10.1002/asna.19141990502. Bibcode: 1914AN....199...65D. 



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