Deneb el Okab, ε Aql, 13 Aql, BD+14 3736, FK5 712, GC 26091, HD 176411, HIP 93244, HR 7176, SAO 104318[10]
Database references
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Epsilon Aquilae, Latinized from ε Aquilae, is the Bayer designation for a binary star[11] system in the equatorial constellation of Aquila, near the western constellation boundary with Hercules. It has an apparent visual magnitude of 4.02[2] and is visible to the naked eye. Based upon an annual parallax of 23.993 mas,[1] Epsilon Aquilae lies at a distance of approximately 136 light-years (42 parsecs) from Earth, but is drifting closer with a radial velocity of –46 km/s.[4]
It has the traditional name Deneb el Okab/ˈdɛnɛbɛlˈoʊkæb/, from an Arabic term ذنب العقاب ðanab al-ʽuqāb "the tail of the eagle", and the Mandarin names Woo/ˈwuː/ and Yuë/ˈjuːeɪ/, derived from and represent the state Wú (吳), an old state was located at the mouth of the Yangtze River, and Yuè (越), an old state in Zhejiang province[12] (together with 19 Capricorni in Twelve States asterism). According to the R.H. Allen's works, it shares names with ζ Aquilae.[13] Epsilon Aquilae is more precisely called Deneb el Okab Borealis, because is situated to the north of Zeta Aquilae, which can therefore be called Deneb el Okab Australis.
The binary nature of this system was reported by German astronomer F. Kustner in 1914, but it was not confirmed until 1974. It is a single-lined spectroscopic binary system;[7] the pair orbit each other over a period of 1,271 days (3.5 years) with an eccentricity (ovalness) of 0.27.[6] There are two visual companions to Epsilon Aquilae, both reported by German astronomer R. Engelmann in 1887. Component B is a magnitude 10.56 star at an angular separation of 122.00″ along a position angle (PA) of 184° relative to the primary, as of 2014. At magnitude 11.25, component C is at a separation of 142.90″ with a PA of 159°, as of 2015.[14]
The primary component of this system is an evolved giant star with a stellar classification of K1-IIICN0.5,[3] showing a mild overabundance of the CN molecule in the spectrum. The chemical abundances of the star suggest it has gone through first dredge-up.[15] It has more than double[7] the mass of the Sun and has expanded to ten[8] times the Sun's radius. The star shines with 54–fold the Sun's luminosity, which is being radiated from its outer envelope at an effective temperature of 4,760 K.[8] At this heat, it glows with the orange-hue of a K-type star.[16] This has been designated a barium star, meaning its atmosphere is extremely enriched with barium and other heavy elements. However, this is disputed, with astronomer Andrew McWilliam (1990) finding normal abundances from an s-process.[7]
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^(in Chinese) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name Archived August 10, 2010, at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
^Star Names - R.H.Allen p.61
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EpsilonAquilae, Latinized from ε Aquilae, is the Bayer designation for a binary star system in the equatorial constellation of Aquila, near the western...
Deneb el Okab refers to two stars in the Aquila constellation: EpsilonAquilae Zeta Aquilae The name derives from the Arabic term ذنب العقاب ðanab al-ʽuqāb...
of the wider system of which Zeta Aquilae is a member in the Washington Double Star Catalog. Zeta and EpsilonAquilae together bore the traditional name...
in the night sky. It has the Bayer designation Alpha Aquilae, which is Latinised from α Aquilae and abbreviated Alpha Aql or α Aql. Altair is an A-type...
Epsilon Eridani (Latinized from ε Eridani), proper name Ran, is a star in the southern constellation of Eridanus. At a declination of −9.46°, it is visible...
Epsilon Indi, Latinized from ε Indi, is a star system located at a distance of approximately 12 light-years from Earth in the southern constellation of...
to the Sun with a radial velocity of −9.8 km/s. Epsilon Scuti was a latter designation of 3 Aquilae. The visible component is a yellow-hued bright giant...
Epsilon Indi Ab is a gas giant exoplanet orbiting the star Epsilon Indi A, about 11.9 light-years away in the constellation of Indus. The planet was confirmed...
Epsilon Eridani b, also known as AEgir [sic], is an exoplanet approximately 10.5 light-years away orbiting the star Epsilon Eridani, in the constellation...
98 2.95 Epsilon Leonis Star 2.98 Epsilon Corvi Star 2.98 Epsilon Geminorum Star 2.99 2.92 Epsilon Aurigae Triple star system 2.99 Zeta Aquilae Binary star...
including Antares A (Alpha Scorpii A). Examples of eclipsing binaries are Epsilon Aurigae (Almaaz), VV Cephei, and V766 Centauri (HR 5171). Angular diameter...
and is identified in the General Catalogue of Variable Stars as V1298 Aquilae. It is a UV Ceti-type variable star and is known to be subject to frequent...
traditional star names, there were some coined in modern times, e.g. "Avior" for Epsilon Carinae (1930), and a number of stars named after people (mostly in the...
one magnitude, the largest variation known being 3.4 magnitudes (V342 Aquilae). The components may have any spectral type, though in most cases the brighter...
dwarf orbiting around it. Zeta Delphini B has a mass of 50±15 MJ. Rho Aquilae at magnitude 4.94 is at about 150 light-years away. Due to its proper motion...
(2007). "Multiperiodic pulsations in the Be stars NW Serpentis and V1446 Aquilae". Astronomy and Astrophysics. 472 (2): 565–570. Bibcode:2007A&A...472....