Y Cygni
Binary star in the constellation Cygnus
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Y Cygni is an eclipsing and double-lined spectroscopic binary star system in the constellation of Cygnus. It is located about 4,900 light-years from Earth. The system was one of the first binaries with a convincing detection of the apsidal precession.[4]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 20h 52m 3.57718s[2] |
| Declination | +34° 39′ 27.4861″[2] |
| Apparent magnitude (V) | 7.3 - 7.9[3] |
| Characteristics | |
| Primary | |
| Spectral type | O9.5V[4] |
| Apparent magnitude (U) | 5.91[citation needed] |
| Apparent magnitude (B) | 6.996[citation needed] |
| Apparent magnitude (V) | 7.287[4] |
| U−B color index | −1.086[4] |
| B−V color index | −0.291[4] |
| Secondary | |
| Spectral type | O9.5V[4] |
| Apparent magnitude (U) | 5.883[citation needed] |
| Apparent magnitude (B) | 6.974[citation needed] |
| Apparent magnitude (V) | 7.265[4] |
| U−B color index | −1.091[4] |
| B−V color index | −0.291[4] |
| Variable type | Algol[3] |
| Astrometry | |
| Proper motion (μ) | RA: +2.763[2] mas/yr Dec.: −15.981[2] mas/yr |
| Parallax (π) | 0.6759±0.0338 mas[2] |
| Distance | 4,900 ly (1,500[4] pc) |
| Absolute magnitude (MV) | −3.59/−3.62[4] |
| Absolute bolometric magnitude (Mbol) | −6.65±0.04/−6.7±0.04[4] |
| Orbit[4] | |
| Primary | Y Cyg A |
| Name | Y Cyg B |
| Period (P) | 2.99633210±0.00000031 d |
| Semi-major axis (a) | 28.72 R☉ |
| Eccentricity (e) | 0.14508 |
| Inclination (i) | 86.474±0.019° |
| Periastron epoch (T) | 2,446,308.66407±0.0001 |
| Argument of periastron (ω) (secondary) | 312.514° |
| Argument of periastron (ω) (primary) | 132.514±0.052° |
| Details[4] | |
| Primary | |
| Mass | 17.72±0.35 M☉ |
| Radius | 5.785±0.091 R☉ |
| Luminosity | 36,000 L☉ |
| Surface gravity (log g) | 4.161±0.014 cgs |
| Temperature | 33,200±200 K |
| Rotational velocity (v sin i) | 132 km/s |
| Age | 2 Myr |
| Secondary | |
| Mass | 17.73±0.3 M☉ |
| Radius | 5.816±0.063 R☉ |
| Luminosity | 37,700 L☉ |
| Surface gravity (log g) | 4.157±0.01 cgs |
| Temperature | 33,521±40 K |
| Rotational velocity (v sin i) | 132 km/s |
| Age | 2 Myr |
| Other designations | |
| Y Cyg, HD 198846, HIP 102999 | |
| Database references | |
| SIMBAD | data |
The two stars, being O-type main-sequence stars, orbit each other with a period of nearly 3 days.[4]
Observation history
The early type of Y Cyg made it a popular target for astronomers in the past, and spectroscopic orbits have been historically computed numerous times.[5] The first of these studies was published in 1920 by John Stanley Plaskett.[6] Extensive spectroscopic studies of Y Cyg were carried out as early as 1930.[7] Several follow-ups to these have been published in 1959,[8] 1971,[9][10] and 1980.[11] The latter of these contained an estimate of the period of apsidal precession.