en 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
Declination	37° 31′ 58.9″
Apparent magnitude (V)	9.0 - 10.8
Characteristics
Spectral type	M3.5 Ia (M2 - M5)
B−V color index	+3.13 - +3.21
Variable type	SRc
Astrometry
Radial velocity (Rv)	−20.97 km/s
Proper motion (μ)	RA: −3.710 mas/yr ; Dec.: −6.307 mas/yr
Parallax (π)	0.5760 ± 0.0500 mas
Distance	5,418+470; −430 ly ; (1,662+144; −132 pc)
Absolute magnitude (MV)	−7.71
Details
Mass	19 M☉
Radius	1,031 R☉
Luminosity	150,000; 204,000+159,000; −56,000 L☉
Temperature	3,535 K
Age	>9 Myr
Other designations
	BC Cyg, HIP 100404, HV 3339, BD+37°3903, IRAS 20197+3722, 2MASS J20213855+3731589
Database references
SIMBAD	data

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. 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]

Louisa Wells discovered that the star's brightness varied, based on the examination of 15 photographic plates. That discovery was announced in 1911.^[14] It was given its variable star designation, BC Cygni, in 1914.^[15] 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]

Notes

^ ^a ^b Applying the Stefan–Boltzmann law with a nominal solar effective temperature of 5,772 K:
${\sqrt {{\biggl (}{\frac {5,772}{3,535}}{\biggr )}^{4}\cdot 10^{5.175}}}=1,031.27\ R_{\odot }$ .
^ This is only the age at which the star enters the red supergiant phase.

References

^ ^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.
^ ^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.
^ ^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.
^ ^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.
^ 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.
^ 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.
^ ^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.
^ 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.
^ 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.
^ 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.
^ 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.
^ 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.
^ "Download Data". aavso.org. AAVSO. Retrieved 1 October 2021.
^ 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. Retrieved 9 December 2024.
^ Dunér, Nils Christofer; Hartwig, Ernst; Müller, G. (September 1914). "Benennung von neu entdeckten veränderlichen Sternen". Astronomische Nachrichten. 199 (5): 65–88. Bibcode:1914AN....199...65D. doi:10.1002/asna.19141990502. Retrieved 9 December 2024.

[radius-8] Applying the Stefan–Boltzmann law with a nominal solar effective temperature of 5,772 K:
${\sqrt {{\biggl (}{\frac {5,772}{3,535}}{\biggr )}^{4}\cdot 10^{5.175}}}=1,031.27\ R_{\odot }$ .

[10] This is only the age at which the star enters the red supergiant phase.

[dr3-1] ^ ^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.

[kiss-2] 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.

[gcvs-3] 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.

[turner-4] 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.

[b-j-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.

[levesque-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.

[Comeron-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.

[Davies2020-9] 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.

[11] 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.

[12] 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.

[13] 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.

[Josselin-14] 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.

[aavso-15] "Download Data". aavso.org. AAVSO. Retrieved 1 October 2021.

[Fleming1911-16] 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. Retrieved 9 December 2024.

[Dunér1914-17] Dunér, Nils Christofer; Hartwig, Ernst; Müller, G. (September 1914). "Benennung von neu entdeckten veränderlichen Sternen". Astronomische Nachrichten. 199 (5): 65–88. Bibcode:1914AN....199...65D. doi:10.1002/asna.19141990502. Retrieved 9 December 2024.

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BC Cygni

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References

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