| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 19h26m 09.12787s[1] |
| Declination | +36° 19′ 04.4369″[1] |
| Apparent magnitude (V) | 5.17[2] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | B8p Si (Fe II)[4] |
| B−V color index | −0.120±0.001[2] |
| Variable type | α2 CVn[5] |
| Astrometry | |
| Radial velocity (Rv) | −22[6] km/s |
| Proper motion (μ) | RA: +3.769[1] mas/yr Dec.: +13.236[1] mas/yr |
| Parallax (π) | 5.8357 ± 0.1372 mas[1] |
| Distance | 560 ± 10 ly (171 ± 4 pc) |
| Absolute magnitude (MV) | −1.51[2] |
| Orbit[7] | |
| Period (P) | 35.0225±0.0002 d |
| Eccentricity (e) | 0.45±0.13 |
| Periastron epoch (T) | 2438929.1±1.1 JD |
| Argument of periastron (ω) (secondary) | 290±21° |
| Semi-amplitude (K1) (primary) | 5.7±0.6 km/s km/s |
| Details[3] | |
| Mass | 4.08±0.18 M☉ |
| Radius | 5.03[8] R☉ |
| Luminosity | 501+130 −103 L☉ |
| Temperature | 12,190+399 −387 K |
| Rotational velocity (v sin i) | 30±4[9] km/s |
| Age | 145 Myr |
| Other designations | |
4 Cyg, V1741 Cygni, BD+36°3557, FK5 3554, GC 26846, HD 183056, HIP 95556, HR 7395, SAO 68301[10] | |
| Database references | |
| SIMBAD | data |
4 Cygni is a binary star[7] system in the northern constellationofCygnus. It is a faintly visible to the naked eye with an apparent visual magnitude of 5.17.[2] The distance to 4 Cygni, as determined from its annual parallax shiftof5.8 mas,[1] is about 560 light years.
This is single-lined spectroscopic binary with an orbital period of 35 days and an eccentricity of 0.45.[7] The visible component is a B-type star with a stellar classificationofB8p Si (Fe II),[4] where the suffix notation indicates this is type of chemically peculiar star known as a silicon star. It displays an overabundance of iron in the visual spectrum, while the star appears helium-weak in the ultraviolet.[4]
4 Cygni A is an Alpha2 Canum Venaticorum variable that varies by 0.02 magnitude over a period of 0.68674 days.[5] The average quadratic field strength of the magnetic fieldis(254.7±57.2)×10−4 T.[11] With an age of 145 million years, it has four[3] times the mass of the Sun and five[8] times the Sun's radius. It radiates around 501 times the Sun's luminosity from its photosphere at an effective temperature of 12,190 K.[3]
