With a declination in excess of 70 degrees north, Epsilon Draconis is principally visible in the northern hemisphere, with southern locations north of 20° South able to see it just above the horizon. The star is circumpolar throughout all of Europe, China, most of India and as far south as the tip of the Baja peninsula in North America as well as other locations around the globe having a latitude greater than ± 20° North. Since Epsilon Draconis has an apparent magnitude of almost 4.0, the star is easily observable to the naked eye as long as one's stargazing is not hampered by the light pollution common to most cities.
The best time for observation is in the evening sky during the summer months, when the "Dragon constellation" passes the meridian at midnight, but given its circumpolar nature in the northern hemisphere, it is visible to most of the world's inhabitants throughout the year.
Properties
Epsilon Draconis is a yellow giant star with a spectral type of G8III. It has a radius that has been estimated at 11 solar radii and a mass of 2.7 solar masses.[6] Compared to most G class stars, Epsilon Draconis is a relatively young star with an estimated age of around 500 million years old.[6] Like the majority of giant stars, Epsilon Draconis rotates slowly on its axis with a rotational velocity of 1.2 km/s, a speed which takes the star approximately 420 days to make one complete revolution.[6]
In 2007, Floor van Leeuwen and his team calibrated the star's apparent magnitude at 3.9974 with an updated parallax of 22.04 ± 0.37 milliarcseconds, yielding a distance of 45.4 parsecs or approximately 148 light years from Earth.[2] Given a surface temperature of 5,068 Kelvin, theoretical calculations would yield a total luminosity for the star of about 60 times the solar luminosity.
Star system
Epsilon Draconis is resolvable as a double star in telescopes of 10 centimeters aperture or larger. The companion has an apparent brightness of 7.3 at an angular distance of 3.2 arcseconds. It is a giant of spectral class F5,[9] orbiting the yellow giant at about 130 astronomical units.[citation needed]
^ abcdefghBrown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
^ abcvan Leeuwen, F (November 2007). "Hipparcos, the New Reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600. Retrieved 2010-12-18.
^Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373.
^ abMermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. SIMBAD. Bibcode:1986EgUBV........0M.
^Soubiran, C.; et al. (2008). "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants". Astronomy and Astrophysics. 480 (1): 91–101. arXiv:0712.1370. Bibcode:2008A&A...480...91S. doi:10.1051/0004-6361:20078788. S2CID 16602121.
^Mallik, Sushma V.; Parthasarathy, M.; Pati, A. K. (October 2003). "Lithium and rotation in F and G dwarfs and subgiants". Astronomy and Astrophysics. 409 (1): 251–261. Bibcode:2003A&A...409..251M. doi:10.1051/0004-6361:20031084. Retrieved 2010-12-18.
^Soubiran, C.; Bienaymé, O.; Mishenina, T. V.; Kovtyukh, V. V. (2008). "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants". Astronomy and Astrophysics. 480 (1): 91–101. arXiv:0712.1370. Bibcode:2008A&A...480...91S. doi:10.1051/0004-6361:20078788. S2CID 16602121.
^Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York, NY: Dover Publications Inc. p. 209. ISBN0-486-21079-0. Retrieved 2010-12-12.
^(in Chinese)中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN978-986-7332-25-7.
^(in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 August 19, 2010, at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
^Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN978-1-931559-44-7.
epsilon, draconis, latinized, from, draconis, fourth, magnitude, star, constellation, draco, this, star, along, with, delta, draconis, altais, draconis, draconis, forms, asterism, known, tāis, meaning, goat, location, draconis, circled, observation, dataepoch,. Epsilon Draconis Latinized from e Draconis is a fourth magnitude star in the constellation Draco This star along with Delta Draconis Altais Pi Draconis and Rho Draconis forms an asterism known as Al Tais meaning the Goat 10 Epsilon DraconisLocation of e Draconis circled Observation dataEpoch J2000 Equinox J2000Constellation DracoRight ascension 19h 48m 10 34973s 1 Declination 70 16 04 5329 1 Apparent magnitude V 3 9974 2 CharacteristicsSpectral type G7IIIbFe 1 3 U B color index 0 48 4 B V color index 0 88 4 AstrometryRadial velocity Rv 2 69 0 23 5 km sProper motion m RA 79 702 1 mas yr Dec 41 078 1 mas yrParallax p 21 2526 0 3016 mas 1 Distance153 2 ly 47 1 0 7 pc Absolute magnitude MV 0 71 2 DetailsMass2 7 6 7 M Radius11 15 0 47 0 56 1 R Luminosity69 6 1 12 1 L Temperature4993 129 103 1 KMetallicity Fe H 0 31 8 dexRotational velocity v sin i 1 2 6 km sAge500 6 MyrOther designationsTyl e Dra 63 Dra AG 70 689 BD 69 1070 GC 27471 HD 188119 HIP 97433 HR 7582 SAO 9540 CCDM J19482 7016AB PLX 4689 IRAS 19483 7008 2MASS J19481035 7016045 9 Database referencesSIMBADdataIn Chinese astronomy 天廚 Tian Chu meaning the Celestial Kitchen refers to an asterism consisting of Epsilon Draconis Delta Draconis Sigma Draconis Rho Draconis 64 Draconis and Pi Draconis 11 Consequently the Chinese name for Epsilon Draconis itself is 天廚三 Tian Chu san English the Third Star of the Celestial Kitchen 12 Most authors do not use a traditional name for this star using instead the Bayer designation 13 but Becvar 1951 listed it as Tyl ˈ t ɪ l 14 15 Contents 1 Visibility 2 Properties 3 Star system 4 See also 5 References 6 External linksVisibility EditWith a declination in excess of 70 degrees north Epsilon Draconis is principally visible in the northern hemisphere with southern locations north of 20 South able to see it just above the horizon The star is circumpolar throughout all of Europe China most of India and as far south as the tip of the Baja peninsula in North America as well as other locations around the globe having a latitude greater than 20 North Since Epsilon Draconis has an apparent magnitude of almost 4 0 the star is easily observable to the naked eye as long as one s stargazing is not hampered by the light pollution common to most cities The best time for observation is in the evening sky during the summer months when the Dragon constellation passes the meridian at midnight but given its circumpolar nature in the northern hemisphere it is visible to most of the world s inhabitants throughout the year Properties EditEpsilon Draconis is a yellow giant star with a spectral type of G8III It has a radius that has been estimated at 11 solar radii and a mass of 2 7 solar masses 6 Compared to most G class stars Epsilon Draconis is a relatively young star with an estimated age of around 500 million years old 6 Like the majority of giant stars Epsilon Draconis rotates slowly on its axis with a rotational velocity of 1 2 km s a speed which takes the star approximately 420 days to make one complete revolution 6 In 2007 Floor van Leeuwen and his team calibrated the star s apparent magnitude at 3 9974 with an updated parallax of 22 04 0 37 milliarcseconds yielding a distance of 45 4 parsecs or approximately 148 light years from Earth 2 Given a surface temperature of 5 068 Kelvin theoretical calculations would yield a total luminosity for the star of about 60 times the solar luminosity Star system EditEpsilon Draconis is resolvable as a double star in telescopes of 10 centimeters aperture or larger The companion has an apparent brightness of 7 3 at an angular distance of 3 2 arcseconds It is a giant of spectral class F5 9 orbiting the yellow giant at about 130 astronomical units citation needed See also EditLists of stars in the constellation Draco Class G Stars Variable star Double starReferences Edit a b c d e f g h Brown A G A et al Gaia collaboration August 2018 Gaia Data Release 2 Summary of the contents and survey properties Astronomy amp Astrophysics 616 A1 arXiv 1804 09365 Bibcode 2018A amp A 616A 1G doi 10 1051 0004 6361 201833051 Gaia DR2 record for this source at VizieR a b c van Leeuwen F November 2007 Hipparcos the New Reduction Astronomy and Astrophysics 474 2 653 664 arXiv 0708 1752 Bibcode 2007A amp A 474 653V doi 10 1051 0004 6361 20078357 S2CID 18759600 Retrieved 2010 12 18 Keenan Philip C McNeil Raymond C 1989 The Perkins catalog of revised MK types for the cooler stars Astrophysical Journal Supplement Series 71 245 Bibcode 1989ApJS 71 245K doi 10 1086 191373 a b Mermilliod J C 1986 Compilation of Eggen s UBV data transformed to UBV unpublished Catalogue of Eggen s UBV Data SIMBAD Bibcode 1986EgUBV 0M Soubiran C et al 2008 Vertical distribution of Galactic disk stars IV AMR and AVR from clump giants Astronomy and Astrophysics 480 1 91 101 arXiv 0712 1370 Bibcode 2008A amp A 480 91S doi 10 1051 0004 6361 20078788 S2CID 16602121 a b c d e f Mallik Sushma V Parthasarathy M Pati A K October 2003 Li abundances and velocities in F and G stars VizieR Centre de Donnees astronomiques de Strasbourg Retrieved 2010 12 18 Mallik Sushma V Parthasarathy M Pati A K October 2003 Lithium and rotation in F and G dwarfs and subgiants Astronomy and Astrophysics 409 1 251 261 Bibcode 2003A amp A 409 251M doi 10 1051 0004 6361 20031084 Retrieved 2010 12 18 Soubiran C Bienayme O Mishenina T V Kovtyukh V V 2008 Vertical distribution of Galactic disk stars IV AMR and AVR from clump giants Astronomy and Astrophysics 480 1 91 101 arXiv 0712 1370 Bibcode 2008A amp A 480 91S doi 10 1051 0004 6361 20078788 S2CID 16602121 a b eps Dra SIMBAD Centre de donnees astronomiques de Strasbourg Retrieved 2010 12 18 Allen R H 1963 Star Names Their Lore and Meaning Reprint ed New York NY Dover Publications Inc p 209 ISBN 0 486 21079 0 Retrieved 2010 12 12 in Chinese 中國星座神話 written by 陳久金 Published by 台灣書房出版有限公司 2005 ISBN 978 986 7332 25 7 in Chinese 香港太空館 研究資源 亮星中英對照表 Archived August 19 2010 at the Wayback Machine Hong Kong Space Museum Accessed on line November 23 2010 Kaler Jim Epsilon Draconis Retrieved 2016 11 24 Kunitzsch Paul Smart Tim 2006 A Dictionary of Modern star Names A Short Guide to 254 Star Names and Their Derivations 2nd rev ed Cambridge Massachusetts Sky Pub ISBN 978 1 931559 44 7 Bakich Michael 1995 The Cambridge Guide to the Constellations Cambridge University Press p 202 ISBN 0521449219 Retrieved 2016 11 24 Tyl External links EditAstrophotographs Epsilon Draconis SkyView Image Epsilon Draconis Retrieved from https en wikipedia org w index php title Epsilon Draconis amp oldid 1079520865, wikipedia, wiki, book, books, library,
