Astronomy:4 Cygni
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| 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[1] mas |
| 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 | |
| Database references | |
| SIMBAD | data |
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]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 2.3 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 3.0 3.1 3.2 3.3 Kochukhov, O.; Bagnulo, S. (2006), "Evolutionary state of magnetic chemically peculiar stars", Astronomy and Astrophysics 450 (2): 763, doi:10.1051/0004-6361:20054596, Bibcode: 2006A&A...450..763K.
- ↑ 4.0 4.1 4.2 Jaschek, M.; Jaschek, C. (October 1980), "Ground-based observations of some stars classified in the satellite ultraviolet with spectral particularities.", Astronomy and Astrophysics Supplement Series 42: 115–118, Bibcode: 1980A&AS...42..115J.
- ↑ 5.0 5.1 Samus, N. N. et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1 61 (1): 80–88, doi:10.1134/S1063772917010085, Bibcode: 2017ARep...61...80S.
- ↑ Wilson, Ralph Elmer (1953), "General catalogue of stellar radial velocities", Washington (Carnegie Institution of Washington): 0, Bibcode: 1953GCRV..C......0W.
- ↑ 7.0 7.1 7.2 Abt, Helmut A.; Snowden, Michael S. (February 1973), "The Binary Frequency for AP Stars", Astrophysical Journal Supplement 25: 137, doi:10.1086/190265, Bibcode: 1973ApJS...25..137A.
- ↑ 8.0 8.1 Shulyak, D. et al. (2014), "Interferometry of chemically peculiar stars: Theoretical predictions versus modern observing facilities", Monthly Notices of the Royal Astronomical Society 443 (2): 1629, doi:10.1093/mnras/stu1259, Bibcode: 2014MNRAS.443.1629S.
- ↑ Royer, F. et al. (2002), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i", Astronomy and Astrophysics 393 (3): 897–912, doi:10.1051/0004-6361:20020943, Bibcode: 2002A&A...393..897R.
- ↑ "4 Cyg". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=4+Cyg.
- ↑ Bychkov, V. D. et al. (2009), "Catalogue of averaged stellar effective magnetic fields - II. Re-discussion of chemically peculiar A and B stars", Monthly Notices of the Royal Astronomical Society 394 (3): 1338, doi:10.1111/j.1365-2966.2008.14227.x, Bibcode: 2009MNRAS.394.1338B.
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