Psi Draconis

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Psi Draconis
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Draco
Right ascension 17h 41m 58.2s
Declination +72° 09′ 11.0″
Apparent magnitude (V) 4.59/5.81
Characteristics
Spectral type F5IV-V/F8V
Astrometry
Distance 71.85 ly
(22.04 pc)
Details
Mass 1.32/1.23 M
Radius 1.8/1.34 R
Luminosity 5.46/2.41 L
Temperature 6,590/6,240 K
Age ?4.9 billion years
Other designations
HIP 86614, GJ 694.1, A GJ 9602 A, WDS J17419+7209 A, TYC 4436-01425-1, IRAS 17428+7210A PSI Dra A, 31 Dra A, HD 162003, HR 6636, BD+72 804, SAO 8890 2MASS J17415635+7208561
Orbit
Period (P) ≈13,700 yr
Semi-major axis (a) 661 AUs"
Eccentricity (e) ?
Other designations
HIP 86620, GJ 694.1 B, GJ 9602 B, WDS J17419+7209 B, TYC 4436-01424-1, PSI Dra B, 31 Dra B, HD 162004, HR 6637, BD+72 805, SAO 8891, 2MASS J17415811+7209251

Psi Draconis (ψ¹ Dra, ψ¹ Draconis) is a star in the constellation Draco. It also has the traditional name Dziban, from the Arabic Adh-Dhi'ban, meaning "The two wolves" or "The two jackals". The primary component of the binary system is suspected to host a substellar companion.

In Chinese astronomy, Dziban is called 女史, Pinyin: Nǚshǐ, meaning Female Protocol, because this star is marking itself and stand alone in Female Protocol asterism, Purple Forbidden enclosure (see : Chinese constellation).[1] 女史 (Nǚshǐ) westernized into Niu She by R.H. Allen, with the meaning is "the Palace Governess", or "a Literary Woman" [2]

Substellar companion?[edit]

Okayama Planet Search team published a paper in late 2008 reporting investigations on radial velocity variations observed for a set of evolved stars, showing possible hints of a substellar companion orbiting Psi1 Draconis A,[3] primary component of the binary system. Probably a brown dwarf, the unseen substellar companion would yield a minimum mass 50 times that of Jupiter and an orbital period of 8.77 years. The unseen companion is still putative, not yet confirmed.

The Psi Draconis planetary system
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(days)
Eccentricity Inclination Radius
b (unconfirmed) ≥50 MJ ≈4.7 3200  ?

References[edit]