# Psi1 Draconis

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Star in the constellation Draco

For other star systems with a similar [Bayer designation](/source/Bayer_designation), see [Psi Draconis](/source/Psi_Draconis).

ψ1 Draconis Location of ψ1 Draconis (circled in red) Observation data Epoch J2000 Equinox ICRS Constellation Draco ψ1 Dra A Right ascension 17h 41m 56.35536s[1] Declination +72° 08′ 55.8481″[1] Apparent magnitude (V) 4.58[2] ψ1 Dra B Right ascension 17h 41m 58.10460s[1] Declination +72° 09′ 24.8581″[1] Apparent magnitude (V) 5.82[3] Characteristics ψ1 Dra A Spectral type F5IV-V[4] U−B color index +0.01[2] B−V color index +0.43[2] ψ1 Dra B Spectral type F8V[5] U−B color index +0.04[2] B−V color index +0.525[2] Astrometry ψ1 Dra A Radial velocity (Rv) −13.30±0.2[6] km/s Proper motion (μ) RA: +25.32[1] mas/yr Dec.: −268.47[1] mas/yr Parallax (π) 43.79±0.45 mas[1] Distance 74.5 ± 0.8 ly (22.8 ± 0.2 pc) ψ1 Dra B Radial velocity (Rv) −11.20±0.3[6] km/s Proper motion (μ) RA: +34.89[1] mas/yr Dec.: −275.94[1] mas/yr Parallax (π) 43.36±0.51 mas[1] Distance 75.2 ± 0.9 ly (23.1 ± 0.3 pc) Orbit[7] Primary ψ1 Dra Aa Name ψ1 Dra Ab Period (P) 6774+271 −167 d Semi-major axis (a) 9.1+0.4 −0.3 AU Eccentricity (e) 0.679+0.006 −0.004 Inclination (i) 31±1° Periastron epoch (T) 2450388+169 −273 Argument of periastron (ω) (secondary) 32.6±0.7° Semi-amplitude (K1) (primary) 5.18+0.04 −0.03 km/s Semi-amplitude (K2) (secondary) 11.1±0.2 km/s Details ψ1 Dra A Mass 1.38+0.15 −0.08 / 0.70±0.07[7] M☉ Radius 1.2–1.3[8] R☉ Surface gravity (log g) 3.90±0.11[9] cgs Temperature 6,544±42 / 4,400±300[7] K Metallicity [Fe/H] −0.10±0.05[9] dex ψ1 Dra B Mass 1.19±0.07[9] M☉ Radius 1.5[8] R☉ Surface gravity (log g) 4.20±0.12[9] cgs Temperature 6,212±75[9] K Age 3.3±1.0[9] Gyr Other designations Dziban, 31 Dra, ADS 10759 AB, Gliese 694.1 ψ1 Dra A: BD+72°804, HD 162003, HIP 86614, HR 6636, SAO 8890[4] ψ1 Dra B: BD+72°805, HD 162004, HIP 86620, HR 6637, SAO 8891[5] Database references SIMBAD ψ1 Dra AB ψ1 Dra A ψ1 Dra B Exoplanet Archive data

**Psi1 Draconis** (**ψ1 Draconis**, abbreviated **Psi1 Dra**, **ψ1 Dra**), also designated **31 Draconis**, is a [triple star system](/source/Star_system) in the northern [constellation](/source/Constellation) of [Draco](/source/Draco_(constellation)). The system is fairly close, and is located about 75 [light-years](/source/Light-year) (23 [parsecs](/source/Parsec)) from the [Sun](/source/Sun), based on its [parallax](/source/Stellar_parallax).[1]

Psi1 Draconis was considered a [binary star](/source/Binary_star) consisting of an [F-type](/source/F-type_star) [subgiant](/source/Subgiant) and an [F-type main-sequence star](/source/F-type_main-sequence_star), designated Psi1 Draconis A (officially named **Dziban** [/ˈzaɪbən/](https://en.wikipedia.org/wiki/Help:IPA/English), from the traditional name of the system)[10] and Psi1 Draconis B, respectively. In 2015, Psi1 Draconis A was itself found to be a double-lined [spectroscopic binary](/source/Spectroscopic_binary), making the system a triple. The companion to Psi1 Draconis A was designated Psi1 Draconis C by its discoverers.[7]

Also in 2015, Psi1 Draconis B was discovered to be orbited by an [exoplanet](/source/Exoplanet), designated Psi1 Draconis Bb.[9]

## Nomenclature

ψ1 Draconis in optical light

*ψ1 Draconis* ([Latinised](/source/Latinisation_of_names) to *Psi1 Draconis*) is the system's [Bayer designation](/source/Bayer_designation) and *31 Draconis* its [Flamsteed designation](/source/Flamsteed_designation). The designation of the components – *ψ1 Draconis A* and *B* – derives from the convention used by the Washington Multiplicity Catalog (WMC) for [multiple star systems](/source/Multiple_star_system), and adopted by the [International Astronomical Union](/source/International_Astronomical_Union) (IAU).[11]

*Psi1 Draconis* bore the traditional name of *Dziban* or *Dsiban,* derived from the [Arabic](/source/Arabic) Adh-Dhi'ban, meaning "The two wolves" or "The two jackals".[12] In 2016, the IAU organized a [Working Group on Star Names](/source/IAU_Working_Group_on_Star_Names) (WGSN)[13] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire [multiple systems](/source/Multiple_star).[14] It approved the name *Dziban* for the component Psi1 Draconis A on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.[10]

In [Chinese astronomy](/source/Chinese_astronomy), Psi1 Draconis is called 女史, [Pinyin](/source/Pinyin): Nǚshǐ, meaning *Female Protocol*, because this star is marking itself and stands alone in the [asterism](/source/Asterism_(astronomy)) *Female Protocol* in the [Purple Forbidden enclosure](/source/Purple_Forbidden_enclosure) (see [Chinese constellation](/source/Chinese_constellation)).[15] 女史 (Nǚshǐ) has been Latinised into *Niu She* by R.H. Allen, meaning "the Palace Governess", or "a Literary Woman".[12]

## Properties

ψ1 Draconis AC and ψ1 Draconis B are separated by about 31 arcseconds. Only a very small fraction of the orbit has been observed: an [orbital period](/source/Orbital_period) of 10,000 years has been calculated,[16] but it is extremely preliminary and likely to be in high error.

ψ1 Draconis A and C have varying [radial velocities](/source/Radial_velocity) in respect to Earth, indicating that there must be orbital motion. The orbital period is estimated to be around 20 years, and the [eccentricity](/source/Orbital_eccentricity) must be fairly high, around 0.679.[7]

## Planetary system

Psi1 Draconis Bb is a [Jupiter](/source/Jupiter)-like [exoplanet](/source/Exoplanet) orbiting Psi1 Draconis B, the secondary star. The planet was discovered when periodic [Doppler shifts](/source/Doppler_shift) in the star's [spectrum](/source/Stellar_spectrum) revealed the presence of a planet, similar to the spectroscopic binary nature of Psi1 Draconis AC. Its [minimum mass](/source/Minimum_mass) is 1.53 [MJ](/source/Jupiter_mass), and it orbits its host star every 8.5 years taking a relatively eccentric orbit.[9]

The ψ1 Draconis B planetary system[9] Companion (in order from star) Mass Semimajor axis (AU) Orbital period (days) Eccentricity Inclination (°) Radius b ≥1.53 ± 0.10 MJ 4.43 ± 0.04 3117 ± 42s 0.40 ± 0.05 — —

## References

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1. ^ [***a***](#cite_ref-SimbadB_5-0) [***b***](#cite_ref-SimbadB_5-1) ["psi01 Dra B"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=psi01+Dra+B). *[SIMBAD](/source/SIMBAD)*. [Centre de données astronomiques de Strasbourg](/source/Centre_de_donn%C3%A9es_astronomiques_de_Strasbourg). Retrieved 17 March 2017.

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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 [Psi1 Draconis](https://en.wikipedia.org/wiki/Psi1_Draconis) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Psi1_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.