BETA SAÚDE
Eta Cygni
Texto da Wikipédia (en), licença CC BY-SA. O BETARUBI mostra o verbete inteiro nesta página — a leitura não continua fora do site.
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 19h 56m 18.37184s[1] |
| Declination | +35° 05′ 00.3224″[1] |
| Apparent magnitude (V) | 3.889[2] |
| Characteristics | |
| Evolutionary stage | red clump[3] |
| Spectral type | K0 III[4] |
| U−B color index | +0.881[2] |
| B−V color index | +1.035[2] |
| Astrometry | |
| Radial velocity (Rv) | −26.57±0.34[1] km/s |
| Proper motion (μ) | RA: −34.165 mas/yr[1] Dec.: −28.393 mas/yr[1] |
| Parallax (π) | 23.5482±0.1078 mas[1] |
| Distance | 138.5 ± 0.6 ly (42.5 ± 0.2 pc) |
| Absolute magnitude (MV) | 0.74[5] |
| Details | |
| Mass | 0.9±0.1[6] M☉ |
| Radius | 10.43±0.05[7] R☉ |
| Luminosity | 60[6] L☉ |
| Surface gravity (log g) | 2.36±0.08[6] cgs |
| Temperature | 4,783±20[8] K |
| Metallicity [Fe/H] | −0.02[6] dex |
| Rotational velocity (v sin i) | 2.2 [9] km/s |
| Other designations | |
| Almighzal, η Cygni, 21 Cygni, BD+34 3798, HD 188947, HIP 98110, HR 7615, SAO 69116, TYC 2677-1816-1, IRAS 19544+3456[10] | |
| Database references | |
| SIMBAD | data |
Eta Cygni (η Cygni), also named Almighzal,[11] 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.[12] Based upon an annual parallax shift of 23.55 mas,[1] it is located 138.5 light years from the Sun.
This is an evolved red clump[3] giant star with a stellar classification of K0 III.[4] It is presently on the horizontal branch and is generating energy through the nuclear fusion of helium at its core. The star has about 0.9 times the mass of the Sun[6] and has expanded to 10 time the Sun's radius.[7] It radiates 60 times the solar luminosity from its outer atmosphere at an effective temperature of 4,780 K.[6]
Eta Cygni has five visual companions,[13] 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.[14]
Al-Mighzal (المِغْزَل), the Wool Spindle, is an Arabic name for the "Northern Cross" of Cygnus, used in oral tradition in Saudi Arabia.[15] The IAU Working Group on Star Names adopted the name Almighzal for this star on 16 July 2026.[11]
References
- 1 2 3 4 5 6 7 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- 1 2 3 4 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.
- 1 2 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, arXiv:1006.3857, Bibcode:2010MNRAS.408.1225P, doi:10.1111/j.1365-2966.2010.17195.x, S2CID 44228180.
- 1 2 Morgan, W. W.; Keenan, P. C. (1973), "Spectral Classification", Annual Review of Astronomy and Astrophysics, 11: 29–50, Bibcode:1973ARA&A..11...29M, doi:10.1146/annurev.aa.11.090173.000333.
- ↑ Cardini, D. (January 2005), "Mg II chromospheric radiative loss rates in cool active and quiet stars", Astronomy and Astrophysics, 430: 303–311, arXiv:astro-ph/0409683, Bibcode:2005A&A...430..303C, doi:10.1051/0004-6361:20041440, S2CID 12136256.
- 1 2 3 4 5 6 Kallinger, T.; Beck, P. G.; Hekker, S.; Huber, D.; Kuschnig, R.; Rockenbauer, M.; Winter, P. M.; Weiss, W. W.; Handler, G.; Moffat, A. F. J.; Pigulski, A.; Popowicz, A.; Wade, G. A.; Zwintz, K. (2019-04-01), "Stellar masses from granulation and oscillations of 23 bright red giants observed by BRITE-Constellation", Astronomy & Astrophysics, 624: A35, arXiv:1902.07531, Bibcode:2019A&A...624A..35K, doi:10.1051/0004-6361/201834514, ISSN 0004-6361
- 1 2 Anugu, Narsireddy; Monnier, John D.; Mérand, Antoine; Flores, Becky; Gallenne, Alexandre; Gies, Douglas R.; Gutierrez, Mayra; Klement, Robert; Kraus, Stefan (2026-07-27), "Empirical H- and K-band Limb Darkening for 31 CHARA Stars: A Near-Infrared Benchmark for Stellar-Atmosphere Models", The Astronomical Journal, arXiv:2607.24956.
- ↑ Luck, R. Earle (September 2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal, 150 (3): 23, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, S2CID 118505114, 88.
- ↑ 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, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209, S2CID 121883397.
- ↑ "eta Cyg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-02-19.
- 1 2 "IAU Catalog of Star Names". Retrieved 19 July 2026.
- ↑ 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.
- ↑ Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
- ↑ 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, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
- ↑ Al-Ajaji, Khalid; Hoffmann, Susanne M. "al-Miġzal (المِغْزَل)". All Skies Encyclopaedia. IAU Working Group on Star Names. Retrieved 19 July 2026.
External links
- Kaler, James B. (September 7, 2012), "Eta Cygni", Stars, University of Illinois, retrieved 2017-02-19.