  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Draco |
| Right ascension | 17h 08m 47.19596s[1] |
| Declination | +65° 42′ 52.8634″[1] |
| Apparent magnitude (V) | +3.17[2] |
| Characteristics | |
| Spectral type | B6 III[3] |
| U−Bcolor index | −0.43[2] |
| B−Vcolor index | −0.11[2] |
| Astrometry | |
| Radial velocity (Rv) | −17[4] km/s |
| Proper motion (μ) | RA: –20.43[1]mas/yr Dec.: +19.61[1]mas/yr |
| Parallax (π) | 9.93±0.35 mas[1] |
| Distance | 330 ± 10 ly (101 ± 4 pc) |
| Absolute magnitude (MV) | −1.88[5] |
| Details | |
| A | |
| Mass | 5.940±1.134[6] M☉ |
| Radius | 6.19±0.49[7] R☉ |
| Luminosity | 883[8] L☉ |
| Surface gravity (log g) | 4.24[3] cgs |
| Temperature | 15,000±800[7] K |
| Metallicity [Fe/H] | −0.95[3] dex |
| Rotational velocity (v sin i) | 55[9] km/s |
| B | |
| Mass | 3.645±0.770[6] M☉ |
| Other designations | |
| 22 Draconis,BD+65 1170,FK5 639,HD 155763,HIP 83895,HR 6396,SAO 17365,WDS 17088+6543[10] | |
| Database references | |
| SIMBAD | data |
Zeta Draconis (ζ Draconis, abbreviatedZet Dra,ζ Dra) is abinary star in the northerncircumpolar constellation ofDraco. With anapparent visual magnitude of +3.17,[2] it is thefifth-brightest member of this generally faint constellation. Its distance from theSun has been measured using theparallax technique, yielding an estimate of roughly 330light-years (100parsecs).[1]
The two components are designated Zeta Draconis A (formally namedAldhibah/ælˈdaɪbə/, after the traditional name of the system)[11] and B.
ζ Draconis (Latinised toZeta Draconis) is the system'sBayer designation. The designations of the two components asZeta Draconis A andB derives from the convention used by the Washington Multiplicity Catalog (WMC) formultiple star systems, and adopted by theInternational Astronomical Union (IAU).[12]
Zeta Draconis has the oldArabic name الذئبal-dhiʼb "the wolf" or "the hyena", given in its feminine form "Al Dhiʼbah" (ذئبة) in Allen (1899) (though he mistranslated it as plural "hyenas", which would be الضباعal-ḍibāʽ).[13] It shares the dual form of the name, الذئبينal-dhiʼbayn, withEta Draconis.[14] It is also known asNodus III (Third Knot, the knot being a loop in the tail of Draco).[15]
In 2016, the IAU organized aWorking Group on Star Names (WGSN)[16] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entiremultiple systems.[17] It approved the nameAldhibah for the component Zeta Draconis A on 5 September 2017. It also approved the nameAthebyne for Eta Draconis A on the same date. Both are now so included in the List of IAU-approved Star Names.[11]
Zeta Draconis is mentioned inHindu texts asTara who was a celestialgoddess married to LordBrhaspati. A divine epic was played out in the night sky when LordChandra, the moon, lusted after and abducted Tara, the blue pole star of Brhaspati, the planetJupiter. By the completion of the epic Tara gives birth to LordBudha, orMercury.[18]
InChinese,紫微左垣 (Zǐ Wēi Zuǒ Yuán), meaningLeft Wall of Purple Forbidden Enclosure, refers to an asterism consisting of Zeta Draconis,Iota Draconis, Eta Draconis,Theta Draconis,Upsilon Draconis,73 Draconis,Gamma Cephei and23 Cassiopeiae.[19] Consequently, theChinese name for Zeta Draconis itself is紫微左垣四 (Zǐ Wēi Zuǒ Yuán sì, English:the Fourth Star of Left Wall of Purple Forbidden Enclosure),[20] representing上弼 (Shǎngbì), meaningThe First Minister.[21] 上弼 (Shǎngbì) is westernized intoShang Pih by R.H. Allen with meaning "the Higher Minister".[22]
Zeta Draconis A is agiant star with astellar classification of B6 III.[3] Compared to the Sun, this star is about six timeslarger[7] and moremassive,[6] and is radiating 880 times as muchluminosity.[8] This energy is being emitted from the star'souter envelope at aneffective temperature of nearly 13,400K.[3] Theazimuthalrotation velocity along the equator is at least 55 km/s.[9]
The northecliptic pole is located atright ascension 18h anddeclination +66.5°.[23] This is located roughly midway betweenDelta Draconis and Zeta Draconis.[24] The north ecliptic pole almost coincides with the south celestial pole ofVenus; Zeta Draconis is also the north pole star ofJupiter.[25]
