Astronomy:Cygnus OB2-8A
 Cygnus OB2 #8A to #8D (lower left) and other OB-type stars with Hubble | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 20h 33m 15.07905s[1] |
| Declination | +41° 18′ 50.4762″[1] |
| Characteristics | |
| Spectral type | O6If + O5.5III(f)[2] |
| U−B color index | +0.15[3] |
| B−V color index | +1.29[3] |
| Astrometry | |
| Radial velocity (Rv) | 125.56[4] km/s |
| Proper motion (μ) | RA: −2.664[4] mas/yr Dec.: −4.895[4] mas/yr |
| Parallax (π) | 0.6058 ± 0.0191[4] mas |
| Distance | 5,400 ± 200 ly (1,650 ± 50 pc) |
| Absolute magnitude (MV) | −6.78[5] |
| Orbit[6] | |
| Period (P) | 21.9 days |
| Semi-major axis (a) | 71 R☉[7] |
| Eccentricity (e) | 0.24 |
| Semi-amplitude (K1) (primary) | 82.8 km/s |
| Semi-amplitude (K2) (secondary) | 95.8 km/s |
| Details[7] | |
| Cyg OB2 #8A1 | |
| Mass | 44.1 M☉ |
| Radius | 20 R☉ |
| Luminosity | 650,000 L☉ |
| Surface gravity (log g) | 3.48 cgs |
| Temperature | 36,800 K |
| Cyg OB2 #8A2 | |
| Mass | 37.4 M☉ |
| Radius | 14.8 R☉ |
| Luminosity | 468,000 L☉ |
| Surface gravity (log g) | 3.67 cgs |
| Temperature | 39,200 K |
| Age | 2[5] Myr |
| Other designations | |
Schulte 8A, 1E 203127+4108.5, TYC 3161-1325-1, ADS 14000 A, 2E 4382, HIP 101425, UBV 17839, AG+41° 1925, 2E 2031.4+4108, IDS 20297+4058, LS III +41 37, Cyg OB2-8A, 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, Gaia DR2 2067784624247057920 | |
| Database references | |
| SIMBAD | data |
Cygnus OB2 #8A is a double-lined spectroscopic binary located near the centre of the Cygnus OB2 association located 5,500 light years away.
Discovery
Until 1951 Cyg OB2 #8 had been known only as an anonymous catalogue entry in the Bonner Durchmusterung. Then it was identified as one of several highly luminous hot stars close together in Cygnus. Despite being commonly referred to as Schulte #8A, the number 8 was first published in an earlier paper.[8] Schulte identified the grouping as a massive stellar association and split star #8 into four components, including #8A.[9]
System
The Cygnus OB2 #8A system contains two massive luminous O class stars in a 21.9 day orbit. The primary is a 44 M☉ supergiant and the secondary is a 37 M☉ giant star.[6] The two stars are not thought to be exchanging mass and their luminosity classes match the main sequence turnoff in the Cyg OB2 association at around O6.[5] The nearby stars Cyg OB2 #8B, #8C, and #8D, originally thought to be a single star, are all massive and luminous class O stars.
References
- ↑ 1.0 1.1 Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V.
- ↑ Cazorla, Constantin; Nazé, Yaël; Rauw, Gregor (2014). "Wind collisions in three massive stars of Cygnus OB2". Astronomy & Astrophysics 561: A92. doi:10.1051/0004-6361/201322539. Bibcode: 2014A&A...561A..92C.
- ↑ 3.0 3.1 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues 2237. Bibcode: 2002yCat.2237....0D.
- ↑ 4.0 4.1 4.2 4.3 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G. Gaia EDR3 record for this source at VizieR.
- ↑ 5.0 5.1 5.2 Negueruela, I.; Marco, A.; Herrero, A.; Clark, J. S. (2008). "New very massive stars in Cygnus OB2". Astronomy and Astrophysics 487 (2): 575. doi:10.1051/0004-6361:200810094. Bibcode: 2008A&A...487..575N.
- ↑ 6.0 6.1 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. doi:10.1051/0004-6361:200400049. Bibcode: 2004A&A...424L..39D.
- ↑ 7.0 7.1 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. doi:10.1111/j.1365-2966.2006.10746.x. Bibcode: 2006MNRAS.371.1280D. http://orbi.ulg.ac.be/bitstream/2268/2772/1/cyg8aDeBecker.pdf.
- ↑ Münch, Luis; Morgan, W. W. (1953). "Notes: A Probable Clustering of Blue Giants in Cygnus". Astrophysical Journal 118: 161. doi:10.1086/145737. Bibcode: 1953ApJ...118..161M.
- ↑ Schulte, D. H. (1956). "New Members of the Association VI Cygni". Astrophysical Journal 124: 530. doi:10.1086/146256. Bibcode: 1956ApJ...124..530S.
External links
- Cygnus OB2-8A on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
Coordinates: 
20h 33m 15.0789s, +41° 18′ 50.494″
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