{{Short description|Star in the constellation Draco}} {{Starbox begin | name = Alruba }} {{Starbox image | image= {{Location mark |image=Draco constellation map.svg|alt=|float=center|width=260 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link= |x=256|y=921 }} |caption=Location of Alruba (circled) }} {{Starbox observe | epoch = [[J2000.0]] | pronounce = {{IPAc-en|æ|l|'|r|uː|b|ə}} | constell = [[Draco (constellation)|Draco]]<ref name=xhip/> | ra = {{RA|17|43|59.17049}}<ref name=dr2/> | dec = {{DEC|+54|48|06.1637}}<ref name=dr2/> | appmag_v = 5.76<ref name=ubv/> }} {{Starbox character | type = Main sequence<ref name=zorec2012/> | class = A0V<ref name=abt/> | b-v = | u-b = | variable = }} {{Starbox astrometry | radial_v = {{Val|-2.0}}<ref name=pulkovo/> | prop_mo_ra = 17.450<ref name=dr2/> | prop_mo_dec = −18.125<ref name=dr2/> | parallax = 7.1436 | p_error = 0.0605 | parallax_footnote =<ref name=dr2/> | absmag_v = −0.3<ref name=xhip/> }} {{Starbox detail | mass = {{Val|2.97|0.07}}<ref name=zorec2012/> | radius = | luminosity = {{Val|146.7|29.6|24.7}}<ref name=zorec2012/> | temperature = {{Val|9226|107|106|fmt=commas}}<ref name=zorec2012/> | gravity = {{Val|3.80|0.10}}<ref name=Wu2011/> | metal_fe = {{Val|−0.40|0.11}}<ref name=Wu2011/> | rotational_velocity = 170<ref name=zorec2012/> | age_myr = 58<ref name=gullikson/> }} {{Starbox catalog | names = {{odlist | name=Alruba | BD=+53°1978 | CPD=–51°9815 | HD=161693 | HIP=86782 | HR=6618 | SAO=30538 }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad = HD+161693 }} {{Starbox end}}
'''Alruba''',<ref name="IAU-LSN"/> a name derived from [[Arabic]] for "the foal", is a suspected [[astrometric binary]]<ref name=Eggleton2008/> [[star]] system in the northern [[circumpolar constellation]] of [[Draco (constellation)|Draco]]. It is just barely visible to the naked eye as a dim point of light with an [[apparent visual magnitude]] of 5.76.<ref name=ubv/> Based on [[stellar parallax|parallax]] measurements obtained during the [[Gaia (spacecraft)|Gaia]] mission, it is located at a distance of about {{Convert|457|ly|pc|0|abbr=off|lk=on}} from the [[Sun]]. The system is drifting closer with a [[radial velocity]] of −2 km/s.<ref name=pulkovo/>
The visible component is an [[A-type main-sequence star]] with a [[stellar classification]] of A0 V.<ref name=abt/> It is about 58 million years old<ref name=gullikson/> with three times the [[mass of the Sun]]<ref name=zorec2012/> and has a high rate of spin, showing a [[projected rotational velocity]] of 170 km/s.<ref name=zorec2012/> The star is radiating 147 times the [[luminosity of the Sun]]<ref name=zorec2012/> from its [[photosphere]] at an [[effective temperature]] of 9,226 K.<ref name=zorec2012/> The system is a source for [[X-ray astronomy|X-ray emission]], which is most likely coming from the unseen companion.<ref name=Schröder2007/>
== 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]]''.<ref name=SIMBAD/>
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 (astronomy)|asterism]] in early [[Arabic astronomy]].<ref name="Allen"/><ref name="Garfinkle"/>
In 2016, the [[International Astronomical Union]] organized a [[IAU Working Group on Star Names|Working Group on Star Names]] (WGSN)<ref name=WGSN/> 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.<ref name=IAU-LSN/>
==References== <references> <ref name=dr2>{{cite DR2|1416872022613598464}}</ref>
<ref name=xhip>{{cite XHIP|86782|mode=cs2|postscript=.}}</ref>
<ref name=Schröder2007>{{citation | title=X-ray emission from A-type stars | last1=Schröder | first1=C. | last2=Schmitt | first2=J. H. M. M. | journal=Astronomy and Astrophysics | volume=475 | issue=2 | pages=677–684 | date=November 2007 | doi=10.1051/0004-6361:20077429 | bibcode=2007A&A...475..677S | postscript=. | doi-access=free }}</ref>
<ref name="Allen">{{citation | last=Allen | first=R. H. | author-link=Richard Hinckley Allen | title=Star Names: Their Lore and Meaning | publisher=[[Dover Publications]] Inc. | isbn=0-486-21079-0 | edition=rep. | date=1963 | pages=207–212 | location=[[New York City|New York]], [[New York (state)|NY]] | url=https://archive.org/details/starnamestheirlo00alle/page/207 | access-date=2020-01-07 | postscript=. }}</ref>
<ref name="Garfinkle">{{citation | postscript=. | last1=Garfinkle|first1=Robert A. | title=Star-Hopping: Your Visa to Viewing the Universe | publisher=[[Cambridge University Press]] | isbn=978-0521598897 | page=183 | edition=2nd | date=2008 | url=https://books.google.com/books?id=40JzBYGREL0C&q=baby+%22Mother+Camels%22+Draco&pg=PA183 }}</ref>
<ref name="IAU-LSN">{{citation | url=https://www.iau.org/public/themes/naming_stars/ | title=Naming Stars | publisher=IAU.org | postscript=. | access-date=2018-07-01 }}</ref>
<ref name=SIMBAD>{{citation | title=HD 161693 -- Star | work=SIMBAD Astronomical Database | publisher=[[Centre de Données astronomiques de Strasbourg]] | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD+161693&submit=submit+id | access-date=2018-07-01 | postscript=. }}</ref>
<ref name=WGSN>{{citation | postscript=. | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=International Astronomical Union {{!}} IAU | website=www.iau.org | access-date=2018-07-01 }}</ref>
<ref name=Eggleton2008>{{citation | last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A. | title=A catalogue of multiplicity among bright stellar systems | journal=Monthly Notices of the Royal Astronomical Society | volume=389 | issue=2 | pages=869–879 |date=September 2008 | doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | postscript=. | bibcode=2008MNRAS.389..869E | arxiv=0806.2878 | s2cid=14878976 }}</ref>
<ref name=zorec2012>{{citation | last1=Zorec | first1=J. | last2=Royer | first2=F. | title=Rotational velocities of A-type stars. IV. Evolution of rotational velocities | journal=Astronomy & Astrophysics | volume=537 | pages=A120 | year=2012 | bibcode=2012A&A...537A.120Z | arxiv=1201.2052 | doi=10.1051/0004-6361/201117691 | s2cid=55586789 | postscript=. }}</ref>
<ref name=Wu2011>{{citation | display-authors=1 | last1=Wu | first1=Yue | last2=Singh | first2=H. P. | last3=Prugniel | first3=P. | last4=Gupta | first4=R. | last5=Koleva | first5=M. | title=Coudé-feed stellar spectral library – atmospheric parameters | journal=Astronomy & Astrophysics | volume=525 | pages=A71 | year=2010 | bibcode=2011A&A...525A..71W | arxiv=1009.1491 | doi=10.1051/0004-6361/201015014 | s2cid=53480665 | postscript=. }}</ref>
<ref name=gullikson>{{citation | display-authors=1 | last1=Gullikson | first1=Kevin | last2=Kraus | first2=Adam | last3=Dodson-Robinson | first3=Sarah | title=The Close Companion Mass-Ratio Distribution of Intermediate-Mass Stars | journal=The Astronomical Journal | volume=152 | issue=2 | pages=40 | year=2016 | bibcode=2016AJ....152...40G | arxiv=1604.06456 | doi=10.3847/0004-6256/152/2/40 | s2cid=119179065 | postscript=. | doi-access=free }}</ref>
<ref name=ubv>{{citation | title=UBV photometry of stars whose positions are accurately known. II | last1=Oja | first1=T. | journal=Astronomy and Astrophysics Supplement Series | volume=59 | pages=461–464 | date=March 1985 | bibcode=1985A&AS...59..461O | postscript=. }}</ref>
<ref name=pulkovo>{{citation | last=Gontcharov | first=G. A. | title=Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system | date=2006| journal=Astronomy Letters | volume=32 | issue=11 | pages=759–771 | bibcode=2006AstL...32..759G | arxiv=1606.08053 | doi=10.1134/S1063773706110065 | s2cid=119231169 | postscript=. }}</ref>
<ref name=abt>{{citation | last1=Abt | first1=Helmut A. | last2=Morrell | first2=Nidia I. | title=The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars | journal=The Astrophysical Journal Supplement Series | volume=99 | pages=135 | year=1995 | postscript=. | bibcode=1995ApJS...99..135A | doi=10.1086/192182 | doi-access=free }}</ref> </references>
{{Stars of Draco|state=collapsed}}
[[Category:A-type main-sequence stars]] [[Category:Draco (constellation)]] [[Category:Henry Draper Catalogue objects|161693]] [[Category:Hipparcos objects|086782]] [[Category:Bright Star Catalogue objects|6618]] [[Category:Stars with proper names|Alruba]] [[Category:Durchmusterung objects|BD+53 1978]]