Cygnus OB2-8A
Template:Short description Template:Correct title
File:Bica2 HST.jpg Cygnus OB2 #8A to #8D (lower left) and other OB-type stars from the Hubble Space Telescope | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus[1] |
| Right ascension | Template:RA[2] |
| Declination | Template:DEC[2] |
| Apparent magnitude (V) | 9.06[3] |
| Characteristics | |
| Spectral type | O6If + O5.5III(f)[4] |
| U−B Template:Engvar | +0.15[5] |
| B−V Template:Engvar | +1.29[5] |
| Astrometry | |
| Radial velocity (Rv) | 125.56[6] km/s |
| Proper motion (μ) | RA: −2.664[6] mas/yr Dec.: −4.895[6] mas/yr |
| Parallax (π) | 0.6058±0.0191 mas[6] |
| Distance | Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc) |
| Absolute magnitude (MV) | −6.78[7] |
| Orbit[8] | |
| Period (P) | 21.9 days |
| Semi-major axis (a) | Template:Solar radius[9] |
| Eccentricity (e) | 0.24 |
| Semi-amplitude (K1) (primary) | 82.8 km/s |
| Semi-amplitude (K2) (secondary) | 95.8 km/s |
| Details[9] | |
| Cyg OB2 #8A1 | |
| Mass | 44.1 Template:Solar mass |
| Radius | 20 Template:Solar radius |
| Luminosity | 650,000 Template:Solar luminosity |
| Surface gravity (log g) | 3.48 cgs |
| Temperature | 36,800 K |
| Cyg OB2 #8A2 | |
| Mass | 37.4 Template:Solar mass |
| Radius | 14.8 Template:Solar radius |
| Luminosity | 468,000 Template:Solar luminosity |
| Surface gravity (log g) | 3.67 cgs |
| Temperature | 39,200 K |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Age | 2[7] 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 |
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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.[10] Schulte identified the grouping as a massive stellar association and split star #8 into four components, including #8A.[11]
System
The Cygnus OB2 #8A system contains two massive luminous O class stars in a 21.9 day orbit. The primary is a Template:Solar mass supergiant and the secondary is a Template:Solar mass giant star.[8] 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.[7] 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
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- ↑ a b c d Template:Cite Gaia EDR3
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