# Alruba

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Alruba
> Markdown URL: https://mediated.wiki/source/Alruba.md
> Source: https://en.wikipedia.org/wiki/Alruba
> Source revision: 1328192813
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

Star in the constellation Draco

Alruba Location of Alruba (circled) Observation data Epoch J2000.0 Equinox J2000.0 Constellation Draco[1] Pronunciation /ælˈruːbə/ Right ascension 17h 43m 59.17049s[2] Declination +54° 48′ 06.1637″[2] Apparent magnitude (V) 5.76[3] Characteristics Evolutionary stage Main sequence[4] Spectral type A0V[5] Astrometry Radial velocity (Rv) −2.0[6] km/s Proper motion (μ) RA: 17.450[2] mas/yr Dec.: −18.125[2] mas/yr Parallax (π) 7.1436±0.0605 mas[2] Distance 457 ± 4 ly (140 ± 1 pc) Absolute magnitude (MV) −0.3[1] Details Mass 2.97±0.07[4] M☉ Luminosity 146.7+29.6 −24.7[4] L☉ Surface gravity (log g) 3.80±0.10[7] cgs Temperature 9,226+107 −106[4] K Metallicity [Fe/H] −0.40±0.11[7] dex Rotational velocity (v sin i) 170[4] km/s Age 58[8] Myr Other designations Alruba, BD+53°1978, CPD–51°9815, HD 161693, HIP 86782, HR 6618, SAO 30538[9] Database references SIMBAD data

**Alruba**,[10] a name derived from [Arabic](/source/Arabic) for "the foal", is a suspected [astrometric binary](/source/Astrometric_binary)[11] [star](/source/Star) system in the northern [circumpolar constellation](/source/Circumpolar_constellation) of [Draco](/source/Draco_(constellation)). It is just barely visible to the naked eye as a dim point of light with an [apparent visual magnitude](/source/Apparent_visual_magnitude) of 5.76.[3] Based on [parallax](/source/Stellar_parallax) measurements obtained during the [Gaia](/source/Gaia_(spacecraft)) mission, it is located at a distance of about 457 [light-years](/source/Light-year) (140 [parsecs](/source/Parsec)) from the [Sun](/source/Sun). The system is drifting closer with a [radial velocity](/source/Radial_velocity) of −2 km/s.[6]

The visible component is an [A-type main-sequence star](/source/A-type_main-sequence_star) with a [stellar classification](/source/Stellar_classification) of A0 V.[5] It is about 58 million years old[8] with three times the [mass of the Sun](/source/Mass_of_the_Sun)[4] and has a high rate of spin, showing a [projected rotational velocity](/source/Projected_rotational_velocity) of 170 km/s.[4] The star is radiating 147 times the [luminosity of the Sun](/source/Luminosity_of_the_Sun)[4] from its [photosphere](/source/Photosphere) at an [effective temperature](/source/Effective_temperature) of 9,226 K.[4] The system is a source for [X-ray emission](/source/X-ray_astronomy), which is most likely coming from the unseen companion.[12]

## Nomenclature

In the *[Henry Draper catalogue](/source/Henry_Draper_catalogue)* this system has the designation **HD 161693**, while it has the identifier **HR 6618** in the *[Bright Star Catalogue](/source/Bright_Star_Catalogue)*.[9]

It bore the traditional [Arabic](/source/Arabic) name الربع *Al Rubaʽ* "the foal" (specifically a young camel born in the spring), a member of the [Mother Camels](/source/Mother_Camels) [asterism](/source/Asterism_(astronomy)) in early [Arabic astronomy](/source/Arabic_astronomy).[13][14]

In 2016, the [International Astronomical Union](/source/International_Astronomical_Union) organized a [Working Group on Star Names](/source/IAU_Working_Group_on_Star_Names) (WGSN)[15] to catalogue and standardize proper names for stars. The WGSN approved the name *Alruba* for this star on 1 June 2018 and it is now so entered on the List of IAU-approved Star Names.[10]

## References

1. ^ [***a***](#cite_ref-xhip_1-0) [***b***](#cite_ref-xhip_1-1) Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", *[Astronomy Letters](/source/Astronomy_Letters)*, **38** (5): 331, [arXiv](/source/ArXiv_(identifier)):[1108.4971](https://arxiv.org/abs/1108.4971), [Bibcode](/source/Bibcode_(identifier)):[2012AstL...38..331A](https://ui.adsabs.harvard.edu/abs/2012AstL...38..331A), [doi](/source/Doi_(identifier)):[10.1134/S1063773712050015](https://doi.org/10.1134%2FS1063773712050015). [XHIP record for this object](https://vizier.cds.unistra.fr/viz-bin/VizieR-4?-ref=VIZ681510a8389ecb&-out.src=V%2F137D%2FXHIP&-nav=cat%3AV%2F137D%26tab%3A{V%2F137D%2FXHIP}%26key%3Asource%3DV%2F137D%2FXHIP%26HTTPPRM%3A&-source=V%2F137D%2FXHIP&-out=HIP&HIP=86782&-out=Comp&-out=Gr&-out=RAJ2000&-out=DEJ2000&-out=Dist&-out=X&-out=Y&-out=Z&-out=SpType&-out=Simbad&-out=Hpmag&-out=Lum&-out=Cst) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-dr2_2-0) [***b***](#cite_ref-dr2_2-1) [***c***](#cite_ref-dr2_2-2) [***d***](#cite_ref-dr2_2-3) [***e***](#cite_ref-dr2_2-4) [Brown, A. G. A.](/source/Anthony_Brown_(scientist)); et al. ([Gaia collaboration](/source/Data_Processing_and_Analysis_Consortium)) (August 2018). ["*Gaia* Data Release 2: Summary of the contents and survey properties"](https://doi.org/10.1051%2F0004-6361%2F201833051). *[Astronomy & Astrophysics](/source/Astronomy_%26_Astrophysics)*. **616**. A1. [arXiv](/source/ArXiv_(identifier)):[1804.09365](https://arxiv.org/abs/1804.09365). [Bibcode](/source/Bibcode_(identifier)):[2018A&A...616A...1G](https://ui.adsabs.harvard.edu/abs/2018A&A...616A...1G). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/201833051](https://doi.org/10.1051%2F0004-6361%2F201833051). [Gaia DR2 record for this source](https://vizier.u-strasbg.fr/viz-bin/VizieR-S?Gaia%20DR2%201416872022613598464) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-ubv_3-0) [***b***](#cite_ref-ubv_3-1) Oja, T. (March 1985), "UBV photometry of stars whose positions are accurately known. II", *Astronomy and Astrophysics Supplement Series*, **59**: 461–464, [Bibcode](/source/Bibcode_(identifier)):[1985A&AS...59..461O](https://ui.adsabs.harvard.edu/abs/1985A&AS...59..461O).

1. ^ [***a***](#cite_ref-zorec2012_4-0) [***b***](#cite_ref-zorec2012_4-1) [***c***](#cite_ref-zorec2012_4-2) [***d***](#cite_ref-zorec2012_4-3) [***e***](#cite_ref-zorec2012_4-4) [***f***](#cite_ref-zorec2012_4-5) [***g***](#cite_ref-zorec2012_4-6) [***h***](#cite_ref-zorec2012_4-7) [***i***](#cite_ref-zorec2012_4-8) Zorec, J.; Royer, F. (2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", *Astronomy & Astrophysics*, **537**: A120, [arXiv](/source/ArXiv_(identifier)):[1201.2052](https://arxiv.org/abs/1201.2052), [Bibcode](/source/Bibcode_(identifier)):[2012A&A...537A.120Z](https://ui.adsabs.harvard.edu/abs/2012A&A...537A.120Z), [doi](/source/Doi_(identifier)):[10.1051/0004-6361/201117691](https://doi.org/10.1051%2F0004-6361%2F201117691), [S2CID](/source/S2CID_(identifier)) [55586789](https://api.semanticscholar.org/CorpusID:55586789).

1. ^ [***a***](#cite_ref-abt_5-0) [***b***](#cite_ref-abt_5-1) Abt, Helmut A.; Morrell, Nidia I. (1995), "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars", *The Astrophysical Journal Supplement Series*, **99**: 135, [Bibcode](/source/Bibcode_(identifier)):[1995ApJS...99..135A](https://ui.adsabs.harvard.edu/abs/1995ApJS...99..135A), [doi](/source/Doi_(identifier)):[10.1086/192182](https://doi.org/10.1086%2F192182).

1. ^ [***a***](#cite_ref-pulkovo_6-0) [***b***](#cite_ref-pulkovo_6-1) Gontcharov, G. A. (2006), "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system", *Astronomy Letters*, **32** (11): 759–771, [arXiv](/source/ArXiv_(identifier)):[1606.08053](https://arxiv.org/abs/1606.08053), [Bibcode](/source/Bibcode_(identifier)):[2006AstL...32..759G](https://ui.adsabs.harvard.edu/abs/2006AstL...32..759G), [doi](/source/Doi_(identifier)):[10.1134/S1063773706110065](https://doi.org/10.1134%2FS1063773706110065), [S2CID](/source/S2CID_(identifier)) [119231169](https://api.semanticscholar.org/CorpusID:119231169).

1. ^ [***a***](#cite_ref-Wu2011_7-0) [***b***](#cite_ref-Wu2011_7-1) Wu, Yue; et al. (2010), "Coudé-feed stellar spectral library – atmospheric parameters", *Astronomy & Astrophysics*, **525**: A71, [arXiv](/source/ArXiv_(identifier)):[1009.1491](https://arxiv.org/abs/1009.1491), [Bibcode](/source/Bibcode_(identifier)):[2011A&A...525A..71W](https://ui.adsabs.harvard.edu/abs/2011A&A...525A..71W), [doi](/source/Doi_(identifier)):[10.1051/0004-6361/201015014](https://doi.org/10.1051%2F0004-6361%2F201015014), [S2CID](/source/S2CID_(identifier)) [53480665](https://api.semanticscholar.org/CorpusID:53480665).

1. ^ [***a***](#cite_ref-gullikson_8-0) [***b***](#cite_ref-gullikson_8-1) Gullikson, Kevin; et al. (2016), "The Close Companion Mass-Ratio Distribution of Intermediate-Mass Stars", *The Astronomical Journal*, **152** (2): 40, [arXiv](/source/ArXiv_(identifier)):[1604.06456](https://arxiv.org/abs/1604.06456), [Bibcode](/source/Bibcode_(identifier)):[2016AJ....152...40G](https://ui.adsabs.harvard.edu/abs/2016AJ....152...40G), [doi](/source/Doi_(identifier)):[10.3847/0004-6256/152/2/40](https://doi.org/10.3847%2F0004-6256%2F152%2F2%2F40), [S2CID](/source/S2CID_(identifier)) [119179065](https://api.semanticscholar.org/CorpusID:119179065).

1. ^ [***a***](#cite_ref-SIMBAD_9-0) [***b***](#cite_ref-SIMBAD_9-1) ["HD 161693 -- Star"](http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD+161693&submit=submit+id), *SIMBAD Astronomical Database*, [Centre de Données astronomiques de Strasbourg](/source/Centre_de_Donn%C3%A9es_astronomiques_de_Strasbourg), retrieved 2018-07-01.

1. ^ [***a***](#cite_ref-IAU-LSN_10-0) [***b***](#cite_ref-IAU-LSN_10-1) [*Naming Stars*](https://www.iau.org/public/themes/naming_stars/), IAU.org, retrieved 2018-07-01.

1. **[^](#cite_ref-Eggleton2008_11-0)** Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", *Monthly Notices of the Royal Astronomical Society*, **389** (2): 869–879, [arXiv](/source/ArXiv_(identifier)):[0806.2878](https://arxiv.org/abs/0806.2878), [Bibcode](/source/Bibcode_(identifier)):[2008MNRAS.389..869E](https://ui.adsabs.harvard.edu/abs/2008MNRAS.389..869E), [doi](/source/Doi_(identifier)):[10.1111/j.1365-2966.2008.13596.x](https://doi.org/10.1111%2Fj.1365-2966.2008.13596.x), [S2CID](/source/S2CID_(identifier)) [14878976](https://api.semanticscholar.org/CorpusID:14878976).

1. **[^](#cite_ref-Schröder2007_12-0)** Schröder, C.; Schmitt, J. H. M. M. (November 2007), "X-ray emission from A-type stars", *Astronomy and Astrophysics*, **475** (2): 677–684, [Bibcode](/source/Bibcode_(identifier)):[2007A&A...475..677S](https://ui.adsabs.harvard.edu/abs/2007A&A...475..677S), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20077429](https://doi.org/10.1051%2F0004-6361%3A20077429).

1. **[^](#cite_ref-Allen_13-0)** [Allen, R. H.](/source/Richard_Hinckley_Allen) (1963), [*Star Names: Their Lore and Meaning*](https://archive.org/details/starnamestheirlo00alle/page/207) (rep. ed.), [New York](/source/New_York_City), [NY](/source/New_York_(state)): [Dover Publications](/source/Dover_Publications) Inc., pp. 207–212, [ISBN](/source/ISBN_(identifier)) [0-486-21079-0](https://en.wikipedia.org/wiki/Special:BookSources/0-486-21079-0), retrieved 2020-01-07. {{[citation](https://en.wikipedia.org/wiki/Template:Citation)}}: ISBN / Date incompatibility ([help](https://en.wikipedia.org/wiki/Help:CS1_errors#invalid_isbn_date))

1. **[^](#cite_ref-Garfinkle_14-0)** Garfinkle, Robert A. (2008), [*Star-Hopping: Your Visa to Viewing the Universe*](https://books.google.com/books?id=40JzBYGREL0C&q=baby+%22Mother+Camels%22+Draco&pg=PA183) (2nd ed.), [Cambridge University Press](/source/Cambridge_University_Press), p. 183, [ISBN](/source/ISBN_(identifier)) [978-0521598897](https://en.wikipedia.org/wiki/Special:BookSources/978-0521598897).

1. **[^](#cite_ref-WGSN_15-0)** ["International Astronomical Union | IAU"](https://www.iau.org/science/scientific_bodies/working_groups/280/), *www.iau.org*, retrieved 2018-07-01.

v t e Constellation of Draco List of stars in Draco Draco in Chinese astronomy Stars Bayer α (Thuban) β (Rastaban) γ (Eltanin) δ (Altais) ε (Tyl) ζ (Aldhibah) η (Athebyne) θ ι (Edasich) κ λ (Giausar) μ (Alrakis) ν (Kuma) ξ (Grumium) ο π ρ σ (Alsafi) τ υ φ χ ψ1 (Dziban) ψ2 ω Flamsteed 4 6 7 (Tianyi) 8 (Taiyi) 10 (i) 15 (A) 18 (g) 19 (h) 26 36 39 (b) 42 (Fafnir) 45 (d) 50 59 64 (e) 68 Variable TW YY AG BY CL CM CX DO EK HP V581 HR 3751 4126 4934 5811 6237 6518 6618 (Alruba) 6817 7137 7783 HD 109246 (Funi) 101364 128717 147379 156279 158259 176693 191939 Other 2MASS 1237+6526 2MASS J17554042+6551277 G 240-72 GD 356 Gliese 420 Gliese 625 Gliese 687 GRW +70 8247 Kepler-4 Kepler-10 Kepler-12 Kepler-90 Kepler-296 KOI-256 LP 71-82 Qatar-1 SDSS J1240+6710 Struve 2398 TOI-1136 WD 1856+534 WISE 1647+5632 WISE 1841+7000 Exoplanets HD 139357 b HD 167042 b ι Dra b (Hypatia) Kepler-4b Kepler-10b c Kepler-12b Kepler-90e f g h i Kepler-296b c d e f TOI-1452 b TrES-2b Star clusters LAMOST 1 Nebulae Cat's Eye Nebula NGC 6742 Galaxies NGC 3147 3197 3735 4121 4125 4221 4236 4319 4331 4332 4363 4441 4513 4545 4589 5678 5777 5866 5866B 5879 5905 5907 5949 5963 5965 5982 5985 6090 6248 6285 6286 6338 6340 6365 6373 6394 6412 6503 6505 6566 6621 6622 6670 6676 6786 6789 Other 1ES 1927+654 1ES 1959+650 3C 249.1 3C 305 3C 319 3C 343 3C 343.1 3C 351 3C 356 3C 371 3C 380 3C 390.3 3C 401 4C +72.26 4C 73.08 8C 1241+735 Abell 2218 BCG Bean galaxy Beaver galaxy BZQ J1727+5510 Draco Dwarf Draco II GB 1508+5714 Goldfish galaxy H1821+643 HFLS3 IERS B1946+708 IRAS F17179+5444 IRAS 18580+6527 J120011.1+680924.8 KKR 25 Markarian 817 Markarian 876 Original TRG PGC 39058 Porphyrion QSO B1823+568 RGZ J172749.5+534647 S5 1803+784 S5 2007+777 SDSS J1715+6008 Tadpole Galaxy UGC 9391 UGC 9405 UGC 11241 UGC 11411 WISEA J145223.62+611707.5 WN B1851+5707 Galaxy clusters Abell 2218 CL1358+62 Draco Supercluster NGC 5866 Group Astronomical events SN 2003jb SN 2005B SN 2016aps Swift J1644+57 Category

---
Adapted from the Wikipedia article [Alruba](https://en.wikipedia.org/wiki/Alruba) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Alruba?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.