<templatestyles src="Template:Sky/styles.css" />Coordinates: Sky map 19h 48m 10.35s, +70° 16′ 04.55″

Epsilon Draconis

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Template:Short description

Epsilon Draconis
Template:Location mark
Location of ε Draconis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Draco
A
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 3.91[2]
B
Right ascension Template:RA[3]
Declination Template:DEC[3]
Apparent magnitude (V) 6.80[4]
Characteristics
A
Evolutionary stage red clump[5]
Spectral type G7IIIbFe-1[6]
U−B Template:Engvar +0.48[7]
B−V Template:Engvar +0.88 [7]
B
Spectral type F6V[8]
B−V Template:Engvar 0.57[4]
Astrometry
A
Radial velocity (Rv)Script error: No such module "val".[1] km/s
Proper motion (μ) RA: +79.486 mas/yr[1]
Dec.: +40.041 mas/yr[1]
Parallax (π)21.3219±0.1256 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
B
Proper motion (μ) RA: +86.898 mas/yr[3]
Dec.: +37.126 mas/yr[3]
Parallax (π)21.3808±0.0403 mas[3]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Details
A
MassScript error: No such module "val".,[9] Script error: No such module "val".[10] Template:Solar mass
RadiusScript error: No such module "val".[9] Template:Solar radius
Luminosity63.1[10] Template:Solar luminosity
Surface gravity (log g)2.61[10] cgs
TemperatureScript error: No such module "val".[11] K
MetallicityTemplate:M/H[9]
Metallicity [Fe/H]Script error: No such module "val".[2] dex
Rotational velocity (v sin i)Script error: No such module "val".[12] km/s
AgeScript error: No such module "val".[10] Gyr
B
Radius1.16[13] Template:Solar radius
Luminosity2.814[13] Template:Solar luminosity
Temperature6,936[13] K
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist[2]
Database references
SIMBADdata

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Epsilon Draconis, Latinized from ε Draconis, is a binary star[8] in the constellation Draco, with a combined apparent magnitude of 3.84,[14] it is the eleventh-brightest star in this rather faint constellation. This star along with Delta Draconis (Altais), Pi Draconis and Rho Draconis forms an asterism known as Al Tāis, meaning "the Goat".[15] The distance to this system has been calculated to be about Script error: No such module "val"., based on stellar parallax measurements.[1]

In Chinese astronomy, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning the Celestial Kitchen, refers to an asterism consisting of Epsilon Draconis, Delta Draconis, Sigma Draconis, Rho Draconis, 64 Draconis and Pi Draconis.[16] Consequently, the Chinese name for Epsilon Draconis itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx.)[17] Most authors do not use a traditional name for this star, using instead the Bayer designation;[5] but Bečvář (1951) listed it as Tyl Script error: No such module "IPAc-en"..[18][19]

Visibility

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 about 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 binary star, whose components can be split in a telescope. They are separated by Script error: No such module "val". as of 2012, translating to a projected separation of Script error: No such module "val"..[5]

The primary of the system has a spectral type of G7IIIbFe-1, which classify it as a is a yellow giant star, a star which ran out of hydrogen at its core and expanded in size.[6] It is visible with apparent magnitude of 3.91.[2] Asteroseismology of this star retrieve a mass of Script error: No such module "val". and a radius over ten times solar.[9] Other estimates suggest masses between 1.5 and 2 solar masses.[10] This star's abundance of elements heavier than helium relative to hydrogen, what astronomers term metallicity, is just half of the Sun's.[9]Template:Efn The effective temperature of the star is Script error: No such module "val".,[11] roughly 800 degrees cooler than the Sun. It seems to have already enabled helium fusion at its core, being a red clump star.[5]

The secondary is a F-type main-sequence star of class F6V,[8] fusing hydrogen into helium at its core. It has an apparent magnitude 6.8[4] and is 14 times fainter than the primary. This star is about 20% times larger, three times brighter and about 1,100 degrees hotter than the Sun.[13]

See also

Notes

Template:Notelist

References

<templatestyles src="Reflist/styles.css" />

  1. ↑ a b c d e f Template:Cite DR3
  2. ↑ a b c d Template:Cite simbad
  3. ↑ a b c d Template:Cite DR3
  4. ↑ a b c Template:Cite simbad
  5. ↑ a b c d Script error: No such module "citation/CS1".
  6. ↑ a b Script error: No such module "Citation/CS1". Epsilon Draconis' database entry at VizieR.
  7. ↑ a b Script error: No such module "Citation/CS1".
  8. ↑ a b c Script error: No such module "Citation/CS1". Epsilon Draconis' database entry at VizieR.
  9. ↑ a b c d e Script error: No such module "Citation/CS1". Epsilon Draconis' database entry at VizieR.
  10. ↑ a b c d e Script error: No such module "Citation/CS1". Epsilon Draconis' database entry at VizieR.
  11. ↑ a b Script error: No such module "Citation/CS1". Epsilon Draconis' database entry at VizieR.
  12. ↑ Script error: No such module "Citation/CS1". Epsilon Draconis' database entry at VizieR.
  13. ↑ a b c d Template:Cite DR2
  14. ↑ Script error: No such module "Citation/CS1".
  15. ↑ Script error: No such module "citation/CS1".
  16. ↑ Template:In lang 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, Template:ISBN.
  17. ↑ Template:In lang 香港太空館 - 研究資源 - 亮星中英對照表 Script error: No such module "webarchive"., Hong Kong Space Museum. Accessed on line November 23, 2010.
  18. ↑ Script error: No such module "citation/CS1".
  19. ↑ Script error: No such module "citation/CS1".

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External links

Template:Stars of Draco

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