# Kappa Velorum

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> Markdown URL: https://mediated.wiki/source/Kappa_Velorum.md
> Source: https://en.wikipedia.org/wiki/Kappa_Velorum
> Source revision: 1346389947
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{{short description|Binary star system in the constellation Vela}}
{{Starbox begin
| name = Kappa Velorum<br/>(Markeb)
}}
{{Starbox image
 | image=
{{Location mark
|image=Vela constellation map.svg
|float=center
|alt=
|label=
|position=right
|width=280
|mark=Red circle.svg
|mark_width=12
|mark_link=κ Velorum
|x=553|y=640
}}
|caption=Location of κ Vel (circled)
}}
{{Starbox observe
| epoch        = J2000
| ra           = {{RA|09|22|06.81761}}<ref name=aaa474_2_653/>
| dec          = {{DEC|−55|00|38.4017}}<ref name=aaa474_2_653/>
| appmag_v     = 2.48<ref name=aaass27_343/>
| constell     = [Vela](/source/Vela_(constellation))
}}
{{Starbox character
| class        = B2&nbsp;V-IV + BV<ref name=Rowan2025/>
| b-v          = −0.20<ref name=aaass27_343/>
| u-b          = −0.78<ref name=aaass27_343/>
| variable     =
}}
{{Starbox astrometry
| radial_v     = {{val|21.8|0.8}}<ref name=Rowan2025/>
| prop_mo_ra   = −11.40<ref name=aaa474_2_653/>
| prop_mo_dec  = +11.52<ref name=aaa474_2_653/>
| parallax     = 5.70
| p_error      = 0.30
| parallax_footnote = <ref name=aaa474_2_653/>
| absmag_v     = −3.74<ref name=Anderson2012/>
}}
{{Starbox orbit
| reference    = <ref name=Rowan2025/>
| period_unitless = {{val|116.795|0.002}} days
| axis_unitless = 1.28&nbsp;[AU](/source/astronomical_unit){{Efn|name=axis}} 
| eccentricity = {{val|0.1761|0.0004}}
| inclination  = {{val|74.03|0.02}}
| node         = {{Val|109.74|0.03}}
| periarg      = {{val|95.79|0.07}}
| k1           = {{val|44|1}}
}}
{{starbox detail
| component1   = A
| source       = 
| mass         = {{val|13|3|2}}<ref name=Rowan2025/>
| radius       = {{solar radius calculator|type=logLT|1=4.12|logLerr=0.05|2=18197|Terr=420|decimals=1}}<ref name=Paunzen2021/>{{efn|name=radius}}
| luminosity   = {{val|13200|1600|1400|fmt=commas}}<ref name=Paunzen2021/>
| temperature  = {{val|18200|400|fmt=commas}}<ref name=Paunzen2021/>
| gravity      = 3.5<ref name=Rowan2025/>
| metal_fe     = {{val|-0.3}}<ref name=Rowan2025/>
| rotational_velocity = 39<ref name=Rowan2025/>
| age_myr      = 40<ref name=Rowan2025/>
| component2   = B
| mass2        = {{val|7.7|0.9|0.8}}<ref name=Rowan2025/>
| temperature2 = {{val|19000|fmt=commas}}<ref name=Rowan2025/>
| metal2_fe    = {{val|-0.3}}<ref name=Rowan2025/>
| age_myr2     = 40<ref name=Rowan2025/>
}}
{{Starbox catalog
| names = Markeb, [HR](/source/Harvard_Revised_catalogue) 3734, [HD](/source/Henry_Draper_catalogue) 81188, [SAO](/source/Smithsonian_Astrophysical_Observatory_Star_Catalog) 236891, FK5 353, CPD−54°2219, GC 12938, [HIP](/source/Hipparcos_catalogue) 45941<ref name=SIMBAD/>
}}
{{Starbox reference
 | Simbad = kap+Vel
}}
{{Starbox end}}

'''Kappa Velorum''' ('''κ Velorum''', abbreviated '''Kappa Vel''', '''κ Vel'''; [proper name](/source/List_of_proper_names_of_stars) '''Markeb'''<ref name="IAU-LSN">{{cite web | url=https://www.iau.org/public/themes/naming_stars/ | title=Naming Stars | publisher=IAU.org | access-date=16 December 2017 | archive-date=10 March 2025 | archive-url=https://web.archive.org/web/20250310063743/https://www.iau.org/public/themes/naming_stars/ | url-status=dead }}</ref> {{IPAc-en|'|m|ɑr|k|E|b}}) is a [binary star](/source/binary_star) system in the southern [constellation](/source/constellation) of [Vela](/source/Vela_(constellation)). The two components are designated Kappa Velorum A and B.

From [parallax](/source/parallax) measurements, this system is located at a distance of roughly {{Convert|572|ly|pc|abbr=off|lk=on}} from the [Sun](/source/Sun). The [apparent visual magnitude](/source/Apparent_magnitude) is 2.48,<ref name=aaass27_343/> making it readily visible to the naked eye in the southern hemisphere. It forms part of an [asterism](/source/asterism_(astronomy)) known as the [False Cross](/source/Asterism_(astronomy)) along with [Delta Velorum](/source/Delta_Velorum), [Iota Carinae](/source/Iota_Carinae) and [Epsilon Carinae](/source/Epsilon_Carinae), so called because it is sometimes mistaken for the [Southern Cross](/source/Crux), causing errors in [astronavigation](/source/Celestial_navigation).<ref>{{cite book|last=Moore|first=Patrick|title=Patrick Moore's Astronomy: Teach Yourself|publisher=Hachette |year=2010|isbn=978-1444129779|url=https://books.google.com/books?id=D7M0Rgc1ONAC&pg=PT127}}</ref>

==Nomenclature==

''κ Velorum'' ([Latinised](/source/Latinisation_of_names) to ''Kappa Velorum'') is the system's [Bayer designation](/source/Bayer_designation). The designations of the two components as ''Kappa Velorum A'' and ''B'' derives from the convention used by the Washington Multiplicity Catalog (WMC) for [multiple star system](/source/Star_system)s, and adopted by the [International Astronomical Union](/source/International_Astronomical_Union) (IAU).<ref name="planetnaming">{{cite arXiv |title=On the naming convention used for multiple star systems and extrasolar planets |date=2010 |eprint=1012.0707 |class=astro-ph.SR |last1= Hessman |first1=F. V. |last2= Dhillon |first2=V. S. |last3= Winget |first3=D. E. |last4= Schreiber |first4=M. R. |last5= Horne |first5=K. |last6= Marsh |first6=T. R. |last7= Guenther |first7=E. |last8= Schwope |first8=A. |last9= Heber |first9=U. }}</ref>

The system had a traditional name ''Markab'',<ref name=burnham1978/> from the [Arabic](/source/Arabic) مركب, ''markab'' meaning "something to ride".<ref name=allen>{{cite book
  |last = Allen
  |first = R. H.
  |author-link = Richard Hinckley Allen
  |date = 1963
  |title = [Star Names: Their Lore and Meaning](/source/Star_Names%3A_Their_Lore_and_Meaning)
  |edition = [rep](/source/Reprint).
  |publisher = [Dover Publications](/source/Dover_Publications) Inc
  |location = [New York](/source/New_York_City), [NY](/source/New_York_(state))
  |isbn = 0-486-21079-0
}}</ref> It was often spelled ''Markeb''<ref name=jha17_1_51/> to distinguish it from similarly named stars such as [Alpha Pegasi](/source/Alpha_Pegasi). In 2016, the IAU organized a [Working Group on Star Names](/source/IAU_Working_Group_on_Star_Names) (WGSN)<ref name="WGSN">{{cite web | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN) | access-date=22 May 2016 | archive-date=29 September 2018 | archive-url=https://web.archive.org/web/20180929151752/https://www.iau.org/science/scientific_bodies/working_groups/280/ | url-status=dead }}</ref> to catalog and standardize proper names for stars. The WGSN approved the name ''Markeb'' for Kappa Velorum on 5 September 2017. ''Markab'' had previously been approved for Alpha Pegasi on 30 June 2016. Both are now included in the List of IAU-approved Star Names.<ref name="IAU-LSN"/>

In [Chinese](/source/Chinese_language), {{lang|zh|天社}} ({{lang|zh-Latn|Tiān Shè}}), meaning ''[Celestial Earth God's Temple](/source/Ghost_(Chinese_constellation))'', refers to an [asterism](/source/Asterism_(astronomy)) consisting of Kappa Velorum, [Gamma<sup>2</sup> Velorum](/source/Gamma_Velorum), [b Velorum](/source/HD_74180) and [Delta Velorum](/source/Delta_Velorum).<ref>{{in lang|zh}} ''中國星座神話'', written by 陳久金. Published by 台灣書房出版有限公司, 2005, {{ISBN|978-986-7332-25-7}}.</ref> Consequently, Kappa Velorum itself is known as {{lang|zh|天社五}} ({{lang|zh-Latn|Tiān Shè wǔ}}), "the Fifth Star of Celestial Earth God's Temple".<ref>{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm 香港太空館 – 研究資源 – 亮星中英對照表] {{webarchive|url=https://web.archive.org/web/20081025110153/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm |date=2008-10-25 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref>

==Properties==

Kappa Velorum is a [spectroscopic binary](/source/Binary_star) system consisting of a pair of stars that complete an [orbit](/source/orbit) around each other with a [period](/source/Orbital_period) of 116.80 days, a [semi-major axis](/source/semi-major_axis) of 1.28&nbsp;[AU](/source/astronomical_unit){{Efn|name=axis}} and an [eccentricity](/source/orbital_eccentricity) of 0.1761.<ref name=Rowan2025/> 

The primary's [stellar classification](/source/stellar_classification) of the pair is B2&nbsp;V{{snd}}IV, which matches the class of a [B-type](/source/Stellar_classification) star that is exhausting the hydrogen at its core and has begun to evolve into a [subgiant star](/source/Subgiant). It is about 13 times more massive than the Sun,<ref name=Rowan2025/> with a [photospheric](/source/photosphere) radius twelve times larger, irradiating 13,000 times more luminosity than the Sun at an [effective temperature](/source/effective_temperature) of {{val|18000|ul=K|fmt=commas}},<ref name=Paunzen2021/> which give Kappa Velorum A the blue-white hue typical of [B-type star](/source/B-type_star)s.<ref name=csiro/> 

The secondary is a [B-type main-sequence star](/source/B-type_main-sequence_star) much less luminous than the primary. It has 7.7 times the mass of the Sun and an [effective temperature](/source/effective_temperature) of 19,000&nbsp;K,<ref name=Rowan2025/> also giving it a blue-white hue.<ref name=csiro/>

=== Interstellar medium ===

Analysis of the [spectrum](/source/stellar_spectrum) of Kappa Velorum shows [absorption lines](/source/Spectral_line) due to the [interstellar medium](/source/interstellar_medium) between Earth and the star. Observation of these features over many years has shown that the lines vary in strength, probably caused by a small dense cloud extending 100–1,000 [au](/source/Astronomical_unit) moving across the line of sight.<ref name=mnras334_2_L33/><ref>{{cite journal|bibcode=2013MNRAS.429..939S|doi=10.1093/mnras/sts310|title=Small-scale structure in the interstellar medium: Time-varying interstellar absorption towards κ Velorum|journal=Monthly Notices of the Royal Astronomical Society|volume=429|issue=2|pages=939|year=2013|last1=Smith|first1=K. T.|last2=Fossey|first2=S. J.|last3=Cordiner|first3=M. A.|last4=Sarre|first4=P. J.|last5=Smith|first5=A. M.|last6=Bell|first6=T. A.|last7=Viti|first7=S.|author7-link=Serena Viti|doi-access=free |arxiv = 1210.8136 }}</ref>

{{clear}}

==Notes==
{{Notelist|notes=

{{Efn|name=radius|1=Calculated, using the [Stefan-Boltzmann law](/source/Stefan-Boltzmann_law) and the star's [effective temperature](/source/effective_temperature) and luminosity, with respect to the [solar](/source/Sun) nominal effective temperature of 5,772&nbsp;[K](/source/Kelvin):<math display="block">\sqrt{\biggl(\frac{5,772}{10^{4.26}}\biggr)^4 \cdot 10^{4.12}} = 11.55\ R_\odot.</math>}}

{{Efn|name=axis|1=Calculated using the [parallax](/source/parallax) of 5.7 [milliarcsecond](/source/milliarcsecond)s and the separation of 7.272 milliarcseconds. 7.272" / 5.70" = 1.28 [AU](/source/Astronomical_unit).}}

}}

== References ==
{{reflist|25em|refs=

<ref name=aaa474_2_653>{{citation | first=F. | last=van Leeuwen |date=November 2007 | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 |arxiv = 0708.1752 | s2cid=18759600 }}</ref>

<ref name=csiro>{{citation | title=The Colour of Stars | date=December 21, 2004 | work=Australia Telescope, Outreach and Education | publisher=Commonwealth Scientific and Industrial Research Organisation | url=http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html | accessdate=2012-01-16 | archive-date=2013-12-03 | archive-url=https://web.archive.org/web/20131203222826/http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html | url-status=dead }}</ref>

<ref name=Rowan2025>{{Cite arXiv |mode=cs2 |last1=Rowan |first1=D. M. |last2=Kraus |first2=S. |last3=Thompson |first3=Todd A. |title=Hidden in Plain Sight II: Characterizing the luminous companion to Kappa Velorum with VLTI/GRAVITY |date=2025-12-01 |class=astro-ph.SR |eprint=2512.02116 }}</ref>

<ref name=Paunzen2021>{{Citation |last1=Paunzen |first1=E |last2=Supíková |first2=J |last3=Bernhard |first3=K |last4=Hümmerich |first4=S |last5=Prišegen |first5=M |date=2021-07-01 |title=Magnetic chemically peculiar stars investigated by the Solar Mass Ejection Imager  |journal=Monthly Notices of the Royal Astronomical Society |volume=504 |issue=3 |pages=3758–3772 |doi=10.1093/mnras/stab1100 |doi-access=free |arxiv=2105.02206 |bibcode=2021MNRAS.504.3758P |issn=0035-8711}}</ref>

<ref name=aaass27_343>{{citation | last1=Denoyelle | first1=J. | title=The spatial distribution of young stars in Vela (l = 257 to 284 ) | journal=Astronomy and Astrophysics Supplement Series | volume=27 | pages=343–365 |date=March 1977 | bibcode=1977A&AS...27..343D }}</ref>

<ref name=mnras334_2_L33>{{citation | last1=Crawford | first1=I. A. | title=Detection of CaI and CH absorption at the velocity of the variable interstellar component towards κ Velorum | journal=[Monthly Notices of the Royal Astronomical Society](/source/Monthly_Notices_of_the_Royal_Astronomical_Society) | volume=334 | issue=2 | pages=L33–L37 |date=August 2002 | doi=10.1046/j.1365-8711.2002.05730.x | bibcode=2002MNRAS.334L..33C | doi-access=free }}</ref>

<ref name=SIMBAD>{{citation | title=kap Vel -- Spectroscopic binary | website=SIMBAD |publisher=[Centre de Données astronomiques de Strasbourg](/source/Centre_de_Donn%C3%A9es_astronomiques_de_Strasbourg) | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Kappa+Velorum | access-date=2012-01-08 }}</ref>

<ref name=jha17_1_51>{{citation | last1=Kunitzsch | first1=P. | title=John of London and his Unknown Arabic Sources | journal=Journal for the History of Astronomy | volume=17 | issue=1 | page=51 |date=February 1986 | bibcode=1986JHA....17...51K | doi=10.1177/002182868601700104 | s2cid=118089032 }}</ref>

<ref name=burnham1978>{{citation | first1=Robert | last1=Burnham | title=Burnham's celestial handbook: an observer's guide to the universe beyond the solar system | volume=3 | series=Dover books explaining science | edition=2nd | publisher=[Courier Dover Publications](/source/Courier_Dover_Publications) | date=1978 | isbn=0-486-23673-0 | page=2037 | url=https://books.google.com/books?id=PJzIt3SIlkUC&pg=PA2037 | access-date=2012-01-08 }}</ref>

<ref name=Anderson2012>{{citation
 | title=XHIP: An extended hipparcos compilation
 | last1=Anderson | first1=E. | last2=Francis | first2=Ch.
 | journal=Astronomy Letters
 | volume=38 | issue=5 | pages=331 | year=2012
 | bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015
 | arxiv=1108.4971 | s2cid=119257644 | postscript=. }}</ref>

}}

==External links==
* "The path of the Southern Celestial Pole": The System of W. B. Yeats's A Vision [http://www.yeatsvision.com/Astronomy.html] Diagram of the southern precession circle, showing Markeb as the South Pole Star in 9000 AD.
* {{citation | first1=James B. | last1=Kaler | title=MARKEB (Kappa Velorum) | work=Stars | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/markeb.html | access-date=2012-01-08 }}

{{Stars of Vela}}

{{Authority control}}

Velorum, Kappa
081188
045941
3734
Category:Vela (constellation)
Category:B-type subgiants
Category:Spectroscopic binaries
PD-54 02219
Category:Southern pole stars
Markeb
Category:Brightest stars

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