Alruba

Short description: Star in the constellation Draco

Alruba

Location of Alruba (circled)

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

Alruba, BD+53°1978, CPD–51°9815, HD 161693, HIP 86782, HR 6618, SAO 30538[8]

Database references
SIMBAD| data

Alruba,[9] a name derived from Arabic for "the foal", is a suspected astrometric binary[10] star system in the northern circumpolar constellation of Draco. It is just barely visible to the naked eye as a dim point of light with an apparent visual magnitude of 5.76.[2] Based on parallax measurements obtained during the Gaia mission, it is located at a distance of about 457 light-years (140 parsecs) from the Sun. The system is drifting closer with a radial velocity of −2 km/s.[5]

The visible component is an A-type main-sequence star with a stellar classification of A0 V.[4] It is about 58[7] million years old with three[3] times the mass of the Sun and has a high rate of spin, showing a projected rotational velocity of 170 km/s.[3] The star is radiating 147[3] times the luminosity of the Sun from its photosphere at an effective temperature of 9,226 K.[3] The system is a source for X-ray emission, which is most likely coming from the unseen companion.[11]

## Nomenclature

In the Henry Draper catalogue this system has the designation HD 161693, while it has the identifier HR 6618 in the Bright Star Catalogue.[8]

It bore the traditional Arabic name الربع Al Rubaʽ "the foal" (specifically a young camel born in the spring), a member of the Mother Camels asterism in early Arabic astronomy.[12][13]

In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[14] 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.[9]

## References

1. ↑ 1.0 1.1 1.2 1.3 1.4 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
2. ↑ 2.0 2.1 Oja, T. (March 1985), "UBV photometry of stars whose positions are accurately known. II", Astronomy and Astrophysics Supplement Series 59: 461–464, Bibcode: 1985A&AS...59..461O.
3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Zorec, J.; Royer, F. (2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics 537: A120, doi:10.1051/0004-6361/201117691, Bibcode: 2012A&A...537A.120Z.
4. ↑ 4.0 4.1 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, doi:10.1086/192182, Bibcode: 1995ApJS...99..135A.
5. ↑ 5.0 5.1 Gontcharov, G. A. (2006), "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system", Astronomy Letters 32 (11): 759–771, doi:10.1134/S1063773706110065, Bibcode: 2006AstL...32..759G.
6. ↑ 6.0 6.1 Wu, Yue et al. (2010), "Coudé-feed stellar spectral library – atmospheric parameters", Astronomy & Astrophysics 525: A71, doi:10.1051/0004-6361/201015014, Bibcode: 2011A&A...525A..71W.
7. ↑ 7.0 7.1 Gullikson, Kevin et al. (2016), "The Close Companion Mass-Ratio Distribution of Intermediate-Mass Stars", The Astronomical Journal 152 (2): 40, doi:10.3847/0004-6256/152/2/40, Bibcode: 2016AJ....152...40G.
8. ↑ 8.0 8.1 "HD 161693 -- Star", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD+161693&submit=submit+id, retrieved 2018-07-01.
9. ↑ 9.0 9.1 Naming Stars, IAU.org, https://www.iau.org/public/themes/naming_stars/, retrieved 2018-07-01.
10. ↑ 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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E.
11. ↑ Schröder, C.; Schmitt, J. H. M. M. (November 2007), "X-ray emission from A-type stars", Astronomy and Astrophysics 475 (2): 677–684, doi:10.1051/0004-6361:20077429, Bibcode: 2007A&A...475..677S.
12. ↑ Star Names: Their Lore and Meaning (rep. ed.), New York City , NY: Dover Publications Inc., 1963, pp. 207–212, ISBN 0-486-21079-0, https://archive.org/details/starnamestheirlo00alle/page/207, retrieved 2020-01-07.
13. ↑ Garfinkle, Robert A. (2008), Star-Hopping: Your Visa to Viewing the Universe (2nd ed.), Cambridge University Press, p. 183, ISBN 978-0521598897, https://books.google.com/books?id=40JzBYGREL0C&q=baby+"Mother+Camels"+Draco&pg=PA183.
14. ↑ International Astronomical Union | IAU, https://www.iau.org/science/scientific_bodies/working_groups/280/, retrieved 2018-07-01.

* v
* t
* e

Draco constellation

Stars
(list)|

| 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|

* 6
* 7 (Tianyi)
* 8 (Taiyi)
* 10 (i)
* 15 (A)
* 18 (g)
* 19 (h)
* 26
* 36
* 39 (b)
* 42 (Fafnir)
* 45 (d)
* 64 (e)
* 68

Variable|

* AG
* BY
* CL
* CM

HR|

* 3751
* 4126
* 5811
* 6237
* 6618 (Alruba)
* 6817
* 7137
* 7783

HD|

* 81817
* 101364

Gliese|

* Gliese 420
* Gliese 625
* Gliese 687

Kepler|

* 1
* 4
* 10
* 12
* 90
* 296

Other|

* G 240-72
* GD 356
* GRW +70 8247
* LP 71-82
* 2M 1237+6526
* Struve 2398
* WISE 1647+5632

Star clusters|

| Stellar streams|

* LAMOST 1

|

Nebulae|

| Planetary|

* Cat's Eye Nebula

|

Galaxies|

| NGC|

* 3147
* 4121
* 4125
* 4236
* 4319
* 4345
* 4513
* 5866
* 5879
* 5907
* 5949
* 5965
* 5982
* 5985
* 6090
* 6248
* 6285
* 6286
* 6340
* 6373
* 6394
* 6412
* 6503
* 6566
* 6621
* 6670
* 6786

|

Other|

* 3C 249.1
* 3C 305
* 3C 319
* 3C 371
* 3C 390.3
* 3C 401
* H1821+643
* HFLS3
* PGC 39058

Galaxy clusters|

* Abell 2218
* CL1358+62

Other|

* GRB 110328A
* SN 2005B
* Draco Supercluster

* List

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