Cygnus OB2-8A

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The correct title of this article is Cygnus OB2 #8A. The substitution or omission of the # is because of technical restrictions.
Cygnus OB2 #8A

Cygnus OB2 #8A
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension 20h 33m 15.07905s
Declination +41° 18' 50.4762"'
Apparent magnitude (V) 8.99
Spectral type O6If/O5.5III(f)
U−B color index ?
B−V color index ?
Variable type Eclipsing binary
Radial velocity (Rv) -27.7 km/s
Proper motion (μ) RA: -0.91 mas/yr
Dec.: -6.02 mas/yr
Parallax (π) -3.91 ± 1.76 mas
Distance 1,700[1] pc
Absolute magnitude (MV) -7.18/-5.63
Mass 44.1/37.4[1] M
Radius 20/14.8[1] R
Luminosity 650,000/468,000[1] L
Surface gravity (log g) 3.48/3.67[1] cgs
Temperature 36,800/39,200[1] K
Metallicity ?
Rotation ?
Age 6.43 million years
Primary Cyg OB2-#8A1
Companion Cyg Ob2-#8A2
Period (P) 21.9 days[2]
Semi-major axis (a) >35R☉[2]
Eccentricity (e) 0.24[2]
Semi-amplitude (K1)
82.8[2] km/s
Semi-amplitude (K2)
95.8[2] km/s
Other designations
VI CYG 8A, 1E 203127+4108.5, Hilt 996, TYC 3161-1325-1, ADS 14000 A, 2E 4382, HIP 101425, UBV 17839, AG+41° 1925, 2E 2031.4+4108, IDS 20297+4058, ALS 11423, EM* CDS 1173, LS III +41 37, Ass Cyg OB 2-8 A, 1ES 2031+41.1, 2MASS J20331508+4118504, BD+40° 4227, GCRV 20036, PPM 60129, CCDM J20332+4119A, 1RXS J203315.8+411848, CGO 605, GOS G080.22+00.79 01, SAO 49781, CSI+40 4227 1, GSC 03161-01325, Schulte 8A, CXOCyg J203315.07+411850.3, HIC 101425, Schulte 8.
Database references

Cygnus OB2 #8A or TYC 3161-01325-1 is a spectroscopic binary with a period of 21.9 days.[2] It is located near the center of the Cygnus OB2 association.


  1. ^ a b c d e f De Becker, M.; Rauw, G.; Sana, H.; Pollock, A. M. T.; Pittard, J. M.; Blomme, R.; Stevens, I. R.; Van Loo, S. (2006). "XMM-Newton observations of the massive colliding wind binary and non-thermal radio emitter CygOB2#8A [O6If + O5.5III(f)]". Monthly Notices of the Royal Astronomical Society 371 (3): 1280. Bibcode:2006MNRAS.371.1280D. doi:10.1111/j.1365-2966.2006.10746.x.  edit
  2. ^ a b c d e f De Becker, M.; Rauw, G.; Manfroid, J. (2004). "A Spectroscopic study of the non-thermal radio emitter Cyg OB2 #8A: Discovery of a new binary system". Astronomy and Astrophysics 424 (3): L39. arXiv:astro-ph/0408027. Bibcode:2004A&A...424L..39D. doi:10.1051/0004-6361:200400049.  edit

External links[edit]

Coordinates: Sky map 20h 33m 15.0789s, +41° 18′ 50.494″