IC 4756
| IC 4756 | |
|---|---|
 | |
| Observation data (J2000epoch) | |
| Right ascension | 18h38m31.2s[1] |
| Declination | +05° 29′ 24″[1] |
| Distance | 1.3kly(400pc) |
| Apparent magnitude(V) | 4.6[1] |
| Physical characteristics | |
| Other designations | Cr386,Mel210 |
| Associations | |
| Constellation | Serpens |
IC 4756is a large brightopen clusterin the constellationSerpens.Known asGraff's Cluster, it is bright enough to be seen with the naked eye and considered a fine cluster for binoculars or small telescopes.[2]
IC 4756 is also known as the Tweedledee Cluster (paired withNGC 6633as Tweedledum), also as the Secret Garden Cluster.[3]
Metallicityof IC 4756 is similar to the Sun, at -0.02±0.01 dex.[4]
Stars
[edit]There are some noteworthy stars in the cluster.HD 172365[5]is a likely post-blue stragglerin the IC 4756 that contains a large excess oflithium.[6]HD 172189,also in IC 4756, is anAlgol variableeclipsing binary[7]with a 5.70 day period. The primary star in the system is also a Delta Scuti variable, undergoing multiple pulsation frequencies, which, combined with the eclipses, causes the system to vary by around a tenth of a magnitude.[8]
References
[edit]- ^abc"IC 4756".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved30 November2016.
- ^Michael Bakich."The Omega Nebula, Graff's Cluster, and planetary nebula IC 1295".astronomy.com.Retrieved2020-10-05.
- ^O'Meara, Stephen James (2007).Deep-Sky Companions: Hidden Treasures.Cambridge University Press. p. 457-458.ISBN978-0521-83704-0.
- ^Bagdonas, Vilius; Drazdauskas, Arnas; Tautvaišienė, Gražina; Smiljanic, Rodolfo; Chorniy, Yuriy (2018), "Chemical composition of giant stars in the open cluster IC 4756",Astronomy & Astrophysics,615:A165,arXiv:1804.01975,Bibcode:2018A&A...615A.165B,doi:10.1051/0004-6361/201832695,S2CID118857628
- ^"HR 7008 – Star in Cluster".SIMBAD.Retrieved14 December2014.
- ^Andrievsky, S. M.; Gorlova, N. I.; Klochkova, V. G.; Kovtyuch, V. V.; Panchuk, V. E. (1999). "The Lithium-rich supergiant HD172365".Astronomische Nachrichten.320(1): 35–41.Bibcode:1999AN....320...35A.doi:10.1002/1521-3994(199903)320:1<35::aid-asna35>3.0.co;2-f.
- ^Ibanoǧlu, C.; Evren, S.; Taş, G.; Çakırlı, Ö.; Bozkurt, Z.; Afşar, M.; Sipahi, E.; Dal, H. A.; Özdarcan, O.; Çamurdan, D. Z.; Çamurdan, M.; Frasca, A. (2009)."Spectroscopic and photometric observations of the selected Algol-type binaries - IV. V799 Cassiopeiae, BX Piscium and HD 172189".Monthly Notices of the Royal Astronomical Society.392(2): 757.Bibcode:2009MNRAS.392..757I.doi:10.1111/j.1365-2966.2008.14087.x.
- ^Costa, J. E. S.; Michel, E.; Peña, J.; Creevey, O.; Li, Z. P.; Chevreton, M.; Belmonte, J. A.; Alvarez, M.; Fox Machado, L.; Parrao, L.; Pérez Hernéndez, F.; Fernández, A.; Fremy, J. R.; Pau, S.; Alonso, R. (2007). "Pulsational frequencies of the eclipsing δ Scuti star HD 172189. Results of the STEPHI XIII campaign".Astronomy and Astrophysics.468(2): 637–642.arXiv:0706.4083.Bibcode:2007A&A...468..637C.doi:10.1051/0004-6361:20065784.
External links
[edit]
Media related toIC 4756at Wikimedia Commons- IC 4756 onWikiSky:DSS2,SDSS,GALEX,IRAS,Hydrogen α,X-Ray,Astrophoto,Sky Map,Articles and images
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