Mu Draconis
 
| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Draco |
| Right ascension | 17h 05m 20.12403s[1] |
| Declination | +54° 28′ 12.0994″[1] |
| Apparent magnitude (V) | 4.92[2] (5.66 / 5.69)[3] |
| Characteristics | |
| Spectral type | F7V |
| U−B color index | −0.01[4] |
| B−V color index | +0.47[4] |
| Astrometry | |
| Radial velocity (Rv) | −17.30 ± 0.5[5] km/s |
| Proper motion (μ) | RA: −58.16[1] mas/yr Dec.: 67.87[1] mas/yr |
| Parallax (π) | 36.45 ± 0.46[1] mas |
| Distance | 89 ± 1 ly (27.4 ± 0.3 pc) |
| Absolute magnitude (MV) | +2.73[6] |
| Orbit[3] | |
| Primary | μ Dra A |
| Companion | μ Dra B |
| Period (P) | 812.0 ± 70.5 yr |
| Semi-major axis (a) | 4.48 ± 0.03″ |
| Eccentricity (e) | 0.5139 ± 0.029 |
| Inclination (i) | 142.2 ± 1.3° |
| Longitude of the node (Ω) | 282.85 ± 0.80° |
| Periastron epoch (T) | 1946.19 ± 0.72 |
| Argument of periastron (ω) (secondary) | 193.31 ± 0.083° |
| Details | |
| μ Dra A | |
| Mass | 1.35[7] M☉ |
| Metallicity [Fe/H] | −0.01[6] dex |
| μ Dra B | |
| Mass | 1.30[7] M☉ |
| Age | 2.2[6] Gyr |
| Other designations | |
| A: Alrakis, HR 6370, HD 154906 | |
| B: HR 6369, HD 154905 | |
| Database references | |
| SIMBAD | μ Dra |
| μ Dra A | |
| μ Dra B | |
Mu Draconis (μ Draconis, μ Dra), also named Alrakis,[8][9][10] is a binary star near the head of the constellation Draco. With a combined magnitude of 4.92,[2] it is visible to the naked eye. Based on parallax estimates by the Hipparcos spacecraft, it is located approximately 89 light-years from the Solar System.[1]
The component stars are nearly identical F-type main-sequence stars. Both have the spectral class of F5V, and have similar apparent magnitude, at 5.66 and 5.69, respectively.[3] The secondary star has a drifting radial velocity, and it is itself a spectroscopic binary with an unseen companion, with a period of 2,270 days.[11] The companion has a mass of 0.2 M☉. There is also a 14th magnitude common-proper-motion companion 13.2" away from the bright pair, with a mass of 0.29 M☉.[7]
Nomenclature
μ Draconis (Latinised to Mu Draconis) is the star's Bayer designation.
It bore the traditional name Alrakis (also written as Arrakis and Errakis), which is derived from name given to it in Arabic by Arabian stargazers, al-Rāqiṣ, "the Trotting Camel"[9][12] or "the Dancer".[8][12] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[13] to catalogue and standardize proper names for stars. The WGSN approved the name Alrakis for Mu Draconis A on February 1st, 2017 and it is now so entered in the IAU Catalog of Star Names.[10]
This star, along with β Dra (Rastaban), γ Dra (Eltanin), ν Dra (Kuma) and ξ Dra (Grumium) were Al ʽAwāïd, "the Mother Camels", which was later known as the Quinque Dromedarii.[14]
Cultural references
Science fiction writer Frank Herbert chose Arrakis as the name of the primary planet in his famous Dune series of novels, aware that the word "Arrakis" is the transliteration into English of the Arabic words for "the Dancer" (al-Raqis). However, Herbert uses the name not to describe μ Draconis, but the fictional planet Arrakis as the third planet of the star Canopus (α Carinae) in the constellation Carina.
References
- 1 2 3 4 5 6 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 "* mu Dra". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 16 May 2017.
- 1 2 3 "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Retrieved 16 May 2017.
- 1 2 Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV data. Bibcode:1986EgUBV........0M.
- ↑ Holmberg, J.; Nordström, B.; Andersen, J. (2007). "The Geneva-Copenhagen survey of the Solar neighbourhood II". Astronomy and Astrophysics. 475 (2): 519. Bibcode:2007A&A...475..519H. arXiv:0707.1891 . doi:10.1051/0004-6361:20077221.
- 1 2 3 Holmberg, J.; Nordström, B.; Andersen, J. (2009). "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics". Astronomy and Astrophysics. 501 (3): 941. Bibcode:2009A&A...501..941H. doi:10.1051/0004-6361/200811191.
- 1 2 3 Tokovinin, Andrei (2014). "From Binaries to Multiples. II. Hierarchical Multiplicity of F and G Dwarfs". The Astronomical Journal. 147 (4): 87. Bibcode:2014AJ....147...87T. doi:10.1088/0004-6256/147/4/87.
- 1 2 Davis Jr., G. A. (1971). Pronunciations, Derivations, and Meanings of a Selected List of Star Names (rep. ed.). Cambridge, MA: Sky Pub. Corp. p. 13.
- 1 2 Kunitzsch, P.; Smart, T. (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, MA: Sky Pub. p. 35. ISBN 978-1-931559-44-7.
- 1 2 "IAU-CSN".
- ↑ Pourbaix, D.; et al. (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics. 424 (2): 727. Bibcode:2004A&A...424..727P. arXiv:astro-ph/0406573 . doi:10.1051/0004-6361:20041213. (SB9 catalog entry)
- 1 2 Allen, R. H. (1963). Star Names: Their Lore and Meaning (rep. ed.). New York, NY: Dover Publications Inc. p. 211. ISBN 0-486-21079-0.
- ↑ "International Astronomical Union | IAU". www.iau.org. Retrieved 2017-03-31.
- ↑ Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York, NY: Dover Publications Inc. p. 207. ISBN 0-486-21079-0. Retrieved 2010-12-12.