35 Cygni
Binary star in the constellation Cygnus
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35 Cygni is a spectroscopic binary star in the constellation Cygnus. Its apparent magnitude is 5.18. Located around 1,000 parsecs (3,300 ly) distant, its primary is a yellow supergiant of spectral type F6Ib, a massive star that has used up its core hydrogen and is now fusing heavier elements.
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 20h 18m 39.06986s[1] |
| Declination | +34° 58′ 57.9909″[1] |
| Apparent magnitude (V) | 5.18[2] |
| Characteristics | |
| Spectral type | F6Ib[3] |
| B−V color index | +0.62[2] |
| Astrometry | |
| Radial velocity (Rv) | −20.20[4] km/s |
| Proper motion (μ) | RA: −0.05[1] mas/yr Dec.: −3.77[1] mas/yr |
| Parallax (π) | 1.03±0.21 mas[1] |
| Distance | approx. 3,200 ly (approx. 1,000 pc) |
| Absolute magnitude (MV) | −3.99[5] |
| Details | |
| Mass | 10.0[6] M☉ |
| Radius | 51[7] R☉ |
| Luminosity | 7,093[8] L☉ |
| Surface gravity (log g) | 1.5[6] - 2.4[5] cgs |
| Temperature | 6,360[5] K |
| Metallicity [Fe/H] | 0.02[5] dex |
| Rotational velocity (v sin i) | 3.5[6] km/s |
| Age | 22[9] Myr |
| Other designations | |
| 35 Cyg, HR 7770, BD+34°3967, HD 193370, SAO 69806, FK5 3627, HIP 100122 | |
| Database references | |
| SIMBAD | data |
Yellow supergiants are usually variable, often Classical Cepheid variables, but 35 Cyg is notable for having an especially constant brightness.[10]
35 Cyg is a single-lined spectroscopic binary with a period of 2,440 days (over 6 years).[11] The secondary cannot be seen directly, nor can its spectral lines be identified but the overall spectrum can be match by a combination of an F4 supergiant and a less luminous B6.5 star.[12]
It was once designated m Cygni by John Flamsteed and was included in his Atlas Coelestis, but the designation is now dropped.[13]