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?
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.
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b (unconfirmed) | ≥50 MJ | ≈4.7 | 3200 | ? | — | — |
References
- ↑ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 10 日
- ↑ Star Name - R.H. Allen p.212
- ↑ Toyota et al. (2008). "Radial Velocity Search for Extrasolar Planets in Visual Binary Systems". Publications of the Astronomical Society of Japan 61 (1): 19–28. Bibcode:2009PASJ...61...19T.
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