}}{{Starbox reference
| Simbad=4+Cyg
}}{{Starbox end}}4 Cygni is a binary star[13] system in the northern constellation of Cygnus. It is a faintly visible to the naked eye with an apparent visual magnitude of 5.17.[3] The distance to 4 Cygni, as determined from its annual parallax shift of {{Val|5.8|ul=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.[13] The visible component is a B-type star with a stellar classification of {{nowrap|B8p Si (Fe II)}},[5] 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.[5]
4 Cygni A is a Alpha2 Canum Venaticorum variable that varies by 0.02 magnitude over a period of 0.68674 days.[7] The average quadratic field strength of the magnetic field is {{Val|254.7|57.2|e=−4|ul=T}}.[25] With an age of 145 million years, it has four[4] times the mass of the Sun and five[15] 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.[4]
References
1. ^1 2 3 4 5 6 {{Cite Gaia DR2|2050162545236012032}}
2. ^1 {{citation | last=Wilson | first=Ralph Elmer | year=1953 | title=General catalogue of stellar radial velocities | journal=Washington | pages=0 | publisher=Carnegie Institution of Washington | bibcode=1953GCRV..C......0W | postscript=. }}
3. ^1 2 3 4 {{citation | title=XHIP: An extended hipparcos compilation | last1=Anderson | first1=E. | last2=Francis | first2=Ch. | journal=Astronomy Letters | volume=38 | issue=5 | pages=331 | year=2012 | bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015 | arxiv=1108.4971 | postscript=. }}
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7. ^1 2 3 {{citation | title=The Binary Frequency for AP Stars | last1=Abt | first1=Helmut A. | last2=Snowden | first2=Michael S. | journal=Astrophysical Journal Supplement | postscript=. | volume=25 | page=137 | date=February 1973 | doi=10.1086/190265 | bibcode=1973ApJS...25..137A }}
8. ^1 2 3 {{citation | title=Ground-based observations of some stars classified in the satellite ultraviolet with spectral particularities. | last1=Jaschek | first1=M. | last2=Jaschek | first2=C. | journal=Astronomy and Astrophysics Supplement Series | volume=42 | pages=115–118 | date=October 1980 | bibcode=1980A&AS...42..115J | postscript=. }}
9. ^1 2 {{citation | last1=Shulyak | first1=D. | last2=Paladini | first2=C. | last3=Causi | first3=G. Li | last4=Perraut | first4=K. | last5=Kochukhov | first5=O. | display-authors=1 | title=Interferometry of chemically peculiar stars: Theoretical predictions versus modern observing facilities | journal=Monthly Notices of the Royal Astronomical Society | volume=443 | issue=2 | pages=1629 | year=2014 | doi=10.1093/mnras/stu1259 | arxiv=1406.6093 | bibcode=2014MNRAS.443.1629S | postscript=. }}
10. ^1 2 {{citation | last1=Samus | first1=N. N. | last2=Kazarovets | first2=E. V. | last3=Durlevich | first3=O. V. | last4=Kireeva | first4=N. N. | last5=Pastukhova | first5=E. N. | display-authors=1 | title=General Catalogue of Variable Stars | version=5.1 | journal=Astronomy Reports | year=2017 | volume=61 | issue=1 | pages=80–88 | bibcode=2017ARep...61...80S | postscript=. }}