Psi1 Draconis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| 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[1] mas |
| 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[1] mas |
| Distance | 75.2 ± 0.9 ly (23.1 ± 0.3 pc) |
| Orbit[7] | |
| Primary | ψ1 Dra Aa |
| Companion | 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 | 6544 ± 42 / 4400 ± 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 | 6212 ± 75[9] K |
| Age | 3.3 ± 1.0[9] years |
| Other designations | |
| 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 | |
Psi1 Draconis (ψ1 Dra, ψ1 Draconis), also known as Dziban[10] and 31 Draconis, is a star system in the northern constellation of Draco. The system is fairly close, and is located about 75 light-years (23 parsecs) away, based on its parallax.[1]
Nomenclature
ψ1 Draconis (Latinised to Psi1 Draconis) is the system's Bayer 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, and adopted by the International Astronomical Union (IAU).[11]
In Chinese astronomy, Psi1 is called 女史, Pinyin: Nǚshǐ, meaning Female Protocol, because this star is marking itself and stands alone in the asterism Female Protocol in the Purple Forbidden enclosure (see Chinese constellation).[12] 女史 (Nǚshǐ) has been Latinised into Niu She by R.H. Allen, meaning "the Palace Governess", or "a Literary Woman". Psi1 Draconis also bears the traditional name of Dziban or Dsiban, derived from the Arabic Adh-Dhi'ban, meaning "The two wolves" or "The two jackals". [13]
Properties
Psi1 Draconis is a binary star. It consists of two stars, an F-type subgiant and an F-type main-sequence star, designated Psi1 Draconis A and Psi1 Draconis B, respectively. The two stars are separated by about 31 arcseconds. Only a very small fraction of the orbit has been observed: an orbit of with a period 10,000 years has been calculated,[14] but it is extremely preliminary and likely to be in high error.
More recently, Psi1 Draconis A was found to be a binary itself, making the system a triple. It is a double-lined spectroscopic binary. The two components have varying radial velocities in respect to Earth, indicating that there must be orbital motion. The orbital period is estimated to be around 20 years, and the eccentricity must be fairly high, around 0.679.[7]
Exoplanet
In 2015, the discovery of a gas giant planet in the Psi1 Draconis system was announced. Psi1 Draconis Bb is a Jupiter-like exoplanet orbiting Psi1 Draconis B, the secondary star. The planet was discovered when periodic Doppler shifts in the star's spectrum revealed the presence of a planet, similar to the spectroscopic binary nature of Psi1 Draconis A. Its minimum mass is 1.53 MJ, and it orbits its host star every 8.5 years taking a relatively eccentric orbit.[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
- 1 2 3 4 5 6 7 8 9 10 11 van Leeuwen, F.; et al. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. Bibcode:2007A&A...474..653V. arXiv:0708.1752
. doi:10.1051/0004-6361:20078357. - 1 2 3 4 5 Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J.
- ↑ Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV data. Bibcode:1986EgUBV........0M.
- 1 2 "psi01 Dra A". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 17 March 2017.
- 1 2 "psi01 Dra B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 17 March 2017.
- 1 2 Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. Bibcode:2006AstL...32..759G. arXiv:1606.08053 . doi:10.1134/S1063773706110065. Retrieved 12 December 2016.
- 1 2 3 4 Gullikson, Kevin; Endl, Michael; Cochran, William D.; MacQueen, Phillip J. (2015). "MINING PLANET SEARCH DATA FOR BINARY STARS: THE ψ1 DRACONIS SYSTEM". The Astrophysical Journal. 815: 62. arXiv:1511.01903 . doi:10.1088/0004-637X/815/1/62.
- 1 2 Pasinetti Fracassini, L. E.; et al. (2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) – Third edition – Comments and statistics". Astronomy & Astrophysics. 367 (2): 521–24. Bibcode:2001A&A...367..521P. arXiv:astro-ph/0012289 . doi:10.1051/0004-6361:20000451.
- 1 2 3 4 5 6 7 8 Endl, Michael; Brugamyer, Erik J.; Cochran, William D.; MacQueen, Phillip J.; Robertson, Paul; Meschiari, Stefano; Ramirez, Ivan; Shetrone, Matthew; Gullikson, Kevin; Johnson, Marshall C.; Wittenmyer, Robert; Horner, Jonathan; Ciardi, David R.; Horch, Elliott; Simon, Attila E.; Howell, Steve B.; Everett, Mark; Caldwell, Caroline; Castanheira, Barbara G. (2016). "Two New Long-Period Giant Planets from the Mcdonald Observatory Planet Search and Two Stars with Long-Period Radial Velocity Signals Related to Stellar Activity Cycles". The Astrophysical Journal. 818: 34. arXiv:1512.02965 . doi:10.3847/0004-637X/818/1/34.
- ↑ "Dziban". www.constellationsofwords.com. Retrieved 2017-07-28.
- ↑ Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
- ↑ (in 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
- ↑ "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory.