Astronomy:Eta Cygni
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 19h 56m 18.37222s[1] |
| Declination | +35° 05′ 00.3228″[1] |
| Apparent magnitude (V) | 3.889[2] |
| Characteristics | |
| Spectral type | K0 III[3] |
| U−B color index | +0.881[2] |
| B−V color index | +1.035[2] |
| Astrometry | |
| Radial velocity (Rv) | −25.87±0.14[4] km/s |
| Proper motion (μ) | RA: −33.61[1] mas/yr Dec.: −27.87[1] mas/yr |
| Parallax (π) | 24.17 ± 0.15[1] mas |
| Distance | 134.9 ± 0.8 ly (41.4 ± 0.3 pc) |
| Absolute magnitude (MV) | 0.74[5] |
| Details[4] | |
| Mass | 1.59[6] M☉ |
| Radius | 11 R☉ |
| Luminosity | 52.5 L☉ |
| Surface gravity (log g) | 2.7 cgs |
| Temperature | 4,783±20[6] K |
| Metallicity [Fe/H] | −0.09 dex |
| Rotational velocity (v sin i) | 2.2 km/s |
| Age | 3.29[6] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Eta Cygni (η Cygni) is a star in the northern constellation of Cygnus. It is visible to the naked eye with an apparent visual magnitude of 3.889.[2] The star lies along the main body of the constellation, about midway between Gamma Cygni and Albireo.[8] Based upon an annual parallax shift of 24.17 mas,[1] it is located 135 light years from the Sun.
At an age of about 3.3[6] billion years, this is an evolved red clump[9] giant star with a stellar classification of K0 III.[3] It is presently on the horizontal branch and is generating energy through the nuclear fusion of helium at its core. The star has about 1.59[6] times the mass of the Sun and has expanded to 11[4] It radiates 52.5 times the solar luminosity from its outer atmosphere at an effective temperature of 4,783 K.[6]
Eta Cygni has five visual companions,[10] of which only component B appears to be physically associated. This magnitude 12.0 star lies at an angular separation of 7.80 arc seconds along a position angle of 206°, as of 2007.[11]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 2.3 Oja, T. (August 1986), "UBV photometry of stars whose positions are accurately known. III", Astronomy and Astrophysics Supplement Series 65 (2): 405–409, Bibcode: 1986A&AS...65..405O.
- ↑ 3.0 3.1 Morgan, W. W.; Keenan, P. C. (1973), "Spectral Classification", Annual Review of Astronomy and Astrophysics 11: 29–50, doi:10.1146/annurev.aa.11.090173.000333, Bibcode: 1973ARA&A..11...29M.
- ↑ 4.0 4.1 4.2 Massarotti, Alessandro et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal 135 (1): 209–231, doi:10.1088/0004-6256/135/1/209, Bibcode: 2008AJ....135..209M.
- ↑ Cardini, D. (January 2005), "Mg II chromospheric radiative loss rates in cool active and quiet stars", Astronomy and Astrophysics 430: 303–311, doi:10.1051/0004-6361:20041440, Bibcode: 2005A&A...430..303C.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 Luck, R. Earle (September 2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal 150 (3): 23, doi:10.1088/0004-6256/150/3/88, 88, Bibcode: 2015AJ....150...88L.
- ↑ "eta Cyg". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=eta+Cyg.
- ↑ Marett-Crosby, Michael (2013), Twenty-Five Astronomical Observations That Changed the World: And How To Make Them Yourself, The Patrick Moore Practical Astronomy Series, Springer Science & Business Media, p. 231, ISBN 978-1461468004, https://books.google.com/books?id=0KRSphlvsqgC&pg=PA231.
- ↑ Puzeras, E. et al. (October 2010), "High-resolution spectroscopic study of red clump stars in the Galaxy: iron-group elements", Monthly Notices of the Royal Astronomical Society 408 (2): 1225–1232, doi:10.1111/j.1365-2966.2010.17195.x, Bibcode: 2010MNRAS.408.1225P.
- ↑ Mason, B. D. et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal 122 (6): 3466–3471, doi:10.1086/323920, Bibcode: 2001AJ....122.3466M.
- ↑ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society 389 (2): 869–879, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E.
External links
- Kaler, James B. (September 7, 2012), "Eta Cygni", Stars (University of Illinois), http://stars.astro.illinois.edu/sow/etacyg.html, retrieved 2017-02-19.
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