# Upsilon Draconis

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Binary star system  in the constellation Draco

Upsilon Draconis Location of υ Draconis (circled in red) Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) Constellation Draco Right ascension 18h 54m 23.85632s[1] Declination +71° 17′ 49.8906″[1] Apparent magnitude (V) 4.827[2] Characteristics Spectral type K0 III[3] U−B color index +1.10[4] B−V color index +1.15[4] Astrometry Radial velocity (Rv) −11.1[2] km/s Proper motion (μ) RA: +49.53[1] mas/yr Dec.: +42.11[1] mas/yr Parallax (π) 9.48±0.45 mas[1] Distance 340 ± 20 ly (105 ± 5 pc) Absolute bolometric magnitude (Mbol) −0.70[2] Orbit[5] Period (P) 258.48 d Eccentricity (e) 0.21 Periastron epoch (T) 2441977.5 JD Argument of periastron (ω) (secondary) 298° Semi-amplitude (K1) (primary) 6.0 km/s Details Mass 2.05[6] M☉ Radius 19[7] R☉ Luminosity 170[6] L☉ Surface gravity (log g) 2.53[2] cgs Temperature 4,561±61[6] K Metallicity [Fe/H] +0.01[2] dex Age 1.37[6] Gyr Other designations υ Dra, 52 Dra, BD+71°915, HD 176524, HIP 92782, HR 7180, SAO 9283[8] Database references SIMBAD data

**Upsilon Draconis** (**υ Dra**) is a [binary star](/source/Binary_star)[5] system in the northern [circumpolar constellation](/source/Circumpolar_constellation) of [Draco](/source/Draco_(constellation)). It is faintly visible to the naked eye with an [apparent visual magnitude](/source/Apparent_visual_magnitude) of 4.83.[2] Based upon an annual [parallax shift](/source/Stellar_parallax) of 9.48 [mas](/source/Milliarcsecond) as measured from Earth, it is located around 340 [light years](/source/Light_year) (104 [parsecs](/source/Parsecs)) from the [Sun](/source/Sun). At that distance, the visual magnitude of the star is diminished by an [extinction factor](/source/Extinction_(astronomy)) of 0.02 due to [interstellar dust](/source/Interstellar_dust).[9]

In [Chinese](/source/Chinese_astronomy), 紫微左垣 (*Zǐ Wēi Zuǒ Yuán*), meaning *[Left Wall of Purple Forbidden Enclosure](/source/Purple_Forbidden_enclosure)*, refers to an asterism consisting of υ Draconis, [ι Draconis](/source/Iota_Draconis), [η Draconis](/source/Eta_Draconis), [ζ Draconis](/source/Zeta_Draconis), [θ Draconis](/source/Theta_Draconis), [73 Draconis](https://en.wikipedia.org/w/index.php?title=73_Draconis&action=edit&redlink=1), [γ Cephei](/source/Gamma_Cephei) and [23 Cassiopeiae](/source/23_Cassiopeiae).[10]

This is a single-lined [spectroscopic binary](/source/Spectroscopic_binary) star system with an [orbital period](/source/Orbital_period) of 258.48 days and an [eccentricity](/source/Orbital_eccentricity) of 0.21.[5] The primary, component A, is an [evolved](/source/Stellar_evolution) [K-type](/source/K-type_star) [giant star](/source/Giant_star) with a [stellar classification](/source/Stellar_classification) of K0 III.[3] It is a suspected [barium star](/source/Barium_star), which may indicate the orbiting companion, component B, is a [white dwarf](/source/White_dwarf) star.[11]

The measured [angular diameter](/source/Angular_diameter) of the primary, after correction for [limb darkening](/source/Limb_darkening), is 1.69±0.02 [mas](/source/Milliarcsecond).[12] At the estimated distance of Upsilon Draconis, this yields a physical size of about 19 times the [Sun's radius](/source/Sun's_radius).[7] It is about 1.37 billion years old with an estimated 2.05 times the [mass of the Sun](/source/Mass_of_the_Sun).[6] The star is radiating 170 times the [solar luminosity](/source/Solar_luminosity) from its [photosphere](/source/Photosphere) at an [effective temperature](/source/Effective_temperature) of 4,561 K.[6]

## References

1. ^ [***a***](#cite_ref-vanLeeuwen2007_1-0) [***b***](#cite_ref-vanLeeuwen2007_1-1) [***c***](#cite_ref-vanLeeuwen2007_1-2) [***d***](#cite_ref-vanLeeuwen2007_1-3) [***e***](#cite_ref-vanLeeuwen2007_1-4) van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", *Astronomy and Astrophysics*, **474** (2): 653–664, [arXiv](/source/ArXiv_(identifier)):[0708.1752](https://arxiv.org/abs/0708.1752), [Bibcode](/source/Bibcode_(identifier)):[2007A&A...474..653V](https://ui.adsabs.harvard.edu/abs/2007A&A...474..653V), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20078357](https://doi.org/10.1051%2F0004-6361%3A20078357), [S2CID](/source/S2CID_(identifier)) [18759600](https://api.semanticscholar.org/CorpusID:18759600).

1. ^ [***a***](#cite_ref-Luck2007_2-0) [***b***](#cite_ref-Luck2007_2-1) [***c***](#cite_ref-Luck2007_2-2) [***d***](#cite_ref-Luck2007_2-3) [***e***](#cite_ref-Luck2007_2-4) [***f***](#cite_ref-Luck2007_2-5) Luck, R. Earle; Heiter, Ulrike (June 2007), "Giants in the Local Region", *The Astronomical Journal*, **133** (6): 2464–2486, [Bibcode](/source/Bibcode_(identifier)):[2007AJ....133.2464L](https://ui.adsabs.harvard.edu/abs/2007AJ....133.2464L), [doi](/source/Doi_(identifier)):[10.1086/513194](https://doi.org/10.1086%2F513194).

1. ^ [***a***](#cite_ref-Eggen1962_3-0) [***b***](#cite_ref-Eggen1962_3-1) Eggen, O. J. (1962), "Space-velocity vectors for 3483 stars with proper motion and radial velocity", *Royal Observatory Bulletin*, **51**: 79, [Bibcode](/source/Bibcode_(identifier)):[1962RGOB...51...79E](https://ui.adsabs.harvard.edu/abs/1962RGOB...51...79E).

1. ^ [***a***](#cite_ref-Johnson1966_4-0) [***b***](#cite_ref-Johnson1966_4-1) Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", *Communications of the Lunar and Planetary Laboratory*, **4** (99): 99, [Bibcode](/source/Bibcode_(identifier)):[1966CoLPL...4...99J](https://ui.adsabs.harvard.edu/abs/1966CoLPL...4...99J).

1. ^ [***a***](#cite_ref-Pourbaiz2004_5-0) [***b***](#cite_ref-Pourbaiz2004_5-1) [***c***](#cite_ref-Pourbaiz2004_5-2) Pourbaix, D.; et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", *Astronomy and Astrophysics*, **424** (2): 727–732, [arXiv](/source/ArXiv_(identifier)):[astro-ph/0406573](https://arxiv.org/abs/astro-ph/0406573), [Bibcode](/source/Bibcode_(identifier)):[2004A&A...424..727P](https://ui.adsabs.harvard.edu/abs/2004A&A...424..727P), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20041213](https://doi.org/10.1051%2F0004-6361%3A20041213), [S2CID](/source/S2CID_(identifier)) [119387088](https://api.semanticscholar.org/CorpusID:119387088).

1. ^ [***a***](#cite_ref-Luck2015_6-0) [***b***](#cite_ref-Luck2015_6-1) [***c***](#cite_ref-Luck2015_6-2) [***d***](#cite_ref-Luck2015_6-3) [***e***](#cite_ref-Luck2015_6-4) [***f***](#cite_ref-Luck2015_6-5) Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", *Astronomical Journal*, **150** (3), 88, [arXiv](/source/ArXiv_(identifier)):[1507.01466](https://arxiv.org/abs/1507.01466), [Bibcode](/source/Bibcode_(identifier)):[2015AJ....150...88L](https://ui.adsabs.harvard.edu/abs/2015AJ....150...88L), [doi](/source/Doi_(identifier)):[10.1088/0004-6256/150/3/88](https://doi.org/10.1088%2F0004-6256%2F150%2F3%2F88), [S2CID](/source/S2CID_(identifier)) [118505114](https://api.semanticscholar.org/CorpusID:118505114).

1. ^ [***a***](#cite_ref-lang2006_7-0) [***b***](#cite_ref-lang2006_7-1) Lang, Kenneth R. (2006), [*Astrophysical formulae*](https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41), Astronomy and astrophysics library, vol. 1 (3rd ed.), [Birkhäuser](/source/Birkh%C3%A4user), [ISBN](/source/ISBN_(identifier)) [3-540-29692-1](https://en.wikipedia.org/wiki/Special:BookSources/3-540-29692-1). The radius (R*) is given by: 1. 2 ⋅ R ∗ = ( 105.5 ⋅ 1.69 ⋅ 10 − 3 ) AU 0.0046491 AU / R ⨀ ≈ 38 ⋅ R ⨀ {\displaystyle {\begin{aligned}2\cdot R_{*}&={\frac {(105.5\cdot 1.69\cdot 10^{-3})\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 38\cdot R_{\bigodot }\end{aligned}}}

1. **[^](#cite_ref-SIMBAD_8-0)** ["ups Dra -- Spectroscopic binary"](http://simbad.u-strasbg.fr/simbad/sim-id?Ident=ups+Dra), *SIMBAD Astronomical Database*, Centre de Données astronomiques de Strasbourg, retrieved 2017-05-30.

1. **[^](#cite_ref-Famaey2005_9-0)** Famaey, B.; et al. (January 2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", *Astronomy and Astrophysics*, **430**: 165–186, [arXiv](/source/ArXiv_(identifier)):[astro-ph/0409579](https://arxiv.org/abs/astro-ph/0409579), [Bibcode](/source/Bibcode_(identifier)):[2005A&A...430..165F](https://ui.adsabs.harvard.edu/abs/2005A&A...430..165F), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20041272](https://doi.org/10.1051%2F0004-6361%3A20041272), [S2CID](/source/S2CID_(identifier)) [17804304](https://api.semanticscholar.org/CorpusID:17804304).

1. **[^](#cite_ref-10)** (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](/source/ISBN_(identifier)) [978-986-7332-25-7](https://en.wikipedia.org/wiki/Special:BookSources/978-986-7332-25-7).

1. **[^](#cite_ref-Zacs1977_11-0)** Zacs, L.; et al. (April 1997), "An abundance analysis of the single-lined spectroscopic binaries with barium stars-like orbital elements. I. Analysis and results", *Astronomy & Astrophysics Supplement Series*, **122**: 31–42, [Bibcode](/source/Bibcode_(identifier)):[1997A&AS..122...31Z](https://ui.adsabs.harvard.edu/abs/1997A&AS..122...31Z), [doi](/source/Doi_(identifier)):[10.1051/aas:1997330](https://doi.org/10.1051%2Faas%3A1997330).

1. **[^](#cite_ref-Richichi2005_12-0)** Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", *Astronomy and Astrophysics*, **431** (2): 773–777, [Bibcode](/source/Bibcode_(identifier)):[2005A&A...431..773R](https://ui.adsabs.harvard.edu/abs/2005A&A...431..773R), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20042039](https://doi.org/10.1051%2F0004-6361%3A20042039).

v t e Constellation of Draco List of stars in Draco Draco in Chinese astronomy Stars Bayer α (Thuban) β (Rastaban) γ (Eltanin) δ (Altais) ε (Tyl) ζ (Aldhibah) η (Athebyne) θ ι (Edasich) κ λ (Giausar) μ (Alrakis) ν (Kuma) ξ (Grumium) ο π ρ σ (Alsafi) τ υ φ χ ψ1 (Dziban) ψ2 ω Flamsteed 4 6 7 (Tianyi) 8 (Taiyi) 10 (i) 15 (A) 18 (g) 19 (h) 26 36 39 (b) 42 (Fafnir) 45 (d) 50 59 64 (e) 68 Variable TW YY AG BY CL CM CX DO EK HP V581 HR 3751 4126 4934 5811 6237 6518 6618 (Alruba) 6817 7137 7783 HD 109246 (Funi) 101364 128717 147379 156279 158259 176693 191939 Other 2MASS 1237+6526 2MASS J17554042+6551277 G 240-72 GD 356 Gliese 420 Gliese 625 Gliese 687 GRW +70 8247 Kepler-4 Kepler-10 Kepler-12 Kepler-90 Kepler-296 KOI-256 LP 71-82 Qatar-1 SDSS J1240+6710 Struve 2398 TOI-1136 WD 1856+534 WISE 1647+5632 WISE 1841+7000 Exoplanets HD 139357 b HD 167042 b ι Dra b (Hypatia) Kepler-4b Kepler-10b c Kepler-12b Kepler-90e f g h i Kepler-296b c d e f TOI-1452 b TrES-2b Star clusters LAMOST 1 Nebulae Cat's Eye Nebula NGC 6742 Galaxies NGC 3147 3197 3735 4121 4125 4221 4236 4319 4331 4332 4363 4441 4513 4545 4589 5678 5777 5866 5866B 5879 5905 5907 5949 5963 5965 5982 5985 6090 6248 6285 6286 6338 6340 6365 6373 6394 6412 6503 6505 6566 6621 6622 6670 6676 6786 6789 Other 1ES 1927+654 1ES 1959+650 3C 249.1 3C 305 3C 319 3C 343 3C 343.1 3C 351 3C 356 3C 371 3C 380 3C 390.3 3C 401 4C +72.26 4C 73.08 8C 1241+735 Abell 2218 BCG Bean galaxy Beaver galaxy BZQ J1727+5510 Draco Dwarf Draco II GB 1508+5714 Goldfish galaxy H1821+643 HFLS3 IERS B1946+708 IRAS F17179+5444 IRAS 18580+6527 J120011.1+680924.8 KKR 25 Markarian 817 Markarian 876 Original TRG PGC 39058 Porphyrion QSO B1823+568 RGZ J172749.5+534647 S5 1803+784 S5 2007+777 SDSS J1715+6008 Tadpole Galaxy UGC 9391 UGC 9405 UGC 11241 UGC 11411 WISEA J145223.62+611707.5 WN B1851+5707 Galaxy clusters Abell 2218 CL1358+62 Draco Supercluster NGC 5866 Group Astronomical events SN 2003jb SN 2005B SN 2016aps Swift J1644+57 Category

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Adapted from the Wikipedia article [Upsilon Draconis](https://en.wikipedia.org/wiki/Upsilon_Draconis) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Upsilon_Draconis?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.