Cygnus X-1 ❍｜appendage｜___｜20260628155835-01-•

A	B
Location of Cygnus X-1 (circled)	…
Observation data Epoch J2000 Equinox J2000	…
Constellation	Cygnus1
Right ascension	19${}^h$ 58${}^m$ 21.67574${}^s$2
Declination	+35° 12′ 05.7845″2
Apparent magnitude (V)	8.72 - 8.933
Characteristics	…
Spectral type	O9.7Iab4
U−B color index	−0.305
B−V color index	+0.815
Variable type	Ellipsoidal variable3
Astrometry	…
Radial velocity (R${}_v$)	−2.70±3.24 km/s
Proper motion (μ)	RA: −3.812±0.015 mas/yr2 Dec.: −6.310±0.017 mas/yr2
Parallax (π)	0.4439±0.0159 mas2
Distance	7,300 ± 300 ly (2,250 ± 80 pc)
Absolute magnitude (M${}_V$)	−6.5±0.26
Details 7	…
Black hole	…
Mass	13.8 to 17.5${}_{-1.0}^{+2.0}$ M${}_{☉}$
Supergiant	…
Mass	29${}_{-3}^{+6}$ M${}_{☉}$
Radius	22.9${}_{-2.5}^{+1.5}$ R${}_{☉}$
Luminosity	320,000${}_{-65,000}^{+82,000}$ L${}_{☉}$
Surface gravity (log g)	3.17±0.10 cgs
Temperature	28,500±1,000 K
Age	4.8-7.68 Myr
Other designations	…
V1357 Cygni, BD+34°3815, HD 226868, HDE 226868, HIP 98298, SAO 691814	…
Database references	…
SIMBAD	data

Cygnus X-1

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Footnotes

1. Roman, Nancy G. (1987). “Identification of a constellation from a position”. Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP…99..695R. doi:10.1086/132034. Constellation record for this object at VizieR. ↩

2. 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 ↩³ ↩⁴ ↩⁵

3. Samus, N. N.; et al. (2017). “General Catalogue of Variable Stars”. Astronomy Reports. 5.1. 61 (1): 80–88. Bibcode:2017ARep…61…80S. doi:10.1134/S1063772917010085. S2CID 255195566. ↩ ↩²

4. “V1357 Cyg”. SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2008-03-03. ↩ ↩² ↩³

5. Bregman, J.; Butler, D.; Kemper, E.; Koski, A.; Kraft, R. P.; Stone, R. P. S. (1973). “Colors, magnitudes, spectral types and distances for stars in the field of the X-ray source Cyg X-1”. Lick Observatory Bulletin. 647: 1. Bibcode:1973LicOB..24…1B. ↩ ↩²

6. Ninkov, Z.; Walker, G. A. H.; Yang, S. (1987). “The primary orbit and the absorption lines of HDE 226868 (Cygnus X-1)”. Astrophysical Journal. 321: 425–437. Bibcode:1987ApJ…321..425N. doi:10.1086/165641. Archived from the original on 2017-09-22. Retrieved 2018-11-04. ↩

7. Ramachandran, V.; Sander, A. a. C.; Oskinova, L. M.; Schösser, E. C.; Pauli, D.; Hamann, W.-R.; Mahy, L.; Bernini-Peron, M.; Brigitte, M.; Kubátová, B. (2025-04-08). “Comprehensive UV and optical spectral analysis of Cygnus X-1 - Stellar and wind parameters, abundances, and evolutionary implications”. Astronomy & Astrophysics. 698: A37. arXiv:2504.05885. Bibcode:2025A&A…698A..37R. doi:10.1051/0004-6361/202554184. ISSN 0004-6361. ↩

8. Wong, Tsing-Wai; Valsecchi, Francesca; Fragos, Tassos; Kalogera, Vassiliki (February 22, 2012). “Understanding Compact Object Formation And Natal Kicks. III. The Case Of Cygnus X-1”. The Astrophysical Journal. 747 (2). American Astronomical Society: 12. arXiv:1107.5585. Bibcode:2012ApJ…747..111W. doi:10.1088/0004-637X/747/2/111. S2CID 119097709. ↩