4 Cygni

4 Cygni
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension 19h 26m 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]
Distance560 ± 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]
Mass4.08±0.18 M☉
Radius5.03[8] R☉
Luminosity501+130
−103 L☉
Temperature12,190+399
−387 K
Rotational velocity (v sin i)30±4[9] km/s
Age145 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
SIMBADdata

4 Cygni is a binary star[7] system in the northern constellation of Cygnus. 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 shift of 5.8 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 classification of B8p 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 field is (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]

  1. ^ a b c d e f Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference bagnuolo2006 was invoked but never defined (see the help page).
  4. ^ a b c Cite error: The named reference Jaschek1980 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Samus2017 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Wilson1953 was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference Abt1973 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference shulyak2014 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference royer2002 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference bychkov2009 was invoked but never defined (see the help page).