}}{{Starbox catalog
| names = {{odlist | name=Dabih | name2=Dabikh | name3=Dikhabda | F=9 Capricorni | FK5=762 | WDS=J20210-1447AB}}
| component1 = β1 Cap
| names1 = {{odlist | BD=−15° 5629 | HD=193495 | HIP=100345 | HR=7776 | WDS=J20210-1447A}}
| component2 = β2 Cap
| names2 = {{odlist | BD=−15° 5626 | HD=193452 | HIP=100325 | HR=7775 | WDS=J20210-1447B}}
}}{{Starbox reference
| Simbad=bet+Cap | sn=β Cap
| Simbad2=bet01+Cap | sn2=β1 Cap
| Simbad3=bet02+Cap | sn3=β2 Cap
}}{{Starbox end}}Beta Capricorni (β Capricorni, abbreviated Beta Cap, β Cap) is a multiple star system in the constellation of Capricornus and located 328 light-years from the Sun. Because it is near the ecliptic, Beta Capricorni can be occulted by the Moon,[2] and also (rarely) by planets.
The system is believed to consist of five stars.[1] With binoculars or a small telescope, Beta Capricorni can be resolved into a binary pair. The brighter of the two is designated Beta¹ Capricorni or Beta Capricorni A; the dimmer, Beta² Capricorni or Beta Capricorni B. Both are themselves made up of multiple stars. Beta¹ Capricorni has three components; a single star designated Beta Capricorni Aa (also named Dabih[2]) and a binary pair, Beta Capricorni Ab (whose two components are designated Beta Capricorni Ab1 and Ab2). Beta² Capricorni is also a binary pair, with components designated Beta Capricorni Ba and Bb.
Two other nearby stars were discovered by John Herschel. Sometimes referred to as Beta Capricorni D and E, it is unclear whether they are simply optical doubles or part of the Beta Capricorni system.{{cn|date=July 2018}}
Nomenclature
β Capricorni (Latinised to Beta Capricorni) is the system's Bayer designation; β¹ and β² Capricorni those of its two constituents. The designations of the two constituents as Beta Capricorni A and B, and those of the sub-components - Beta Capricorni Aa, Ab, Ab1, Ab2, Ba and Bb - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[3]Beta Capricorni bore the traditional name Dabih, deriving from the Arabic الذابح al-dhābiḥ "the butcher", with Beta¹ and Beta² subsequently named Dabih Major and Dabih Minor, respectively.[4] In 2016, the IAU organized a Working Group on Star Names (WGSN)[5] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[6] It approved the name Dabih for the component Beta Capricorni Aa on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.[2]In Chinese, {{lang|zh|牛宿}} ({{lang|zh-Latn|Niú Su}}), meaning Ox (asterism), refers to an asterism consisting of Beta Capricorni, Alpha² Capricorni, Xi² Capricorni, Pi Capricorni, Omicron Capricorni and Rho Capricorni.[7] Consequently, Beta Capricorni itself is known as {{lang|zh|牛宿一}} ({{lang|zh-Latn|Niú Su yī}}, {{lang-en|the First Star of Ox}}).[8]
Properties
Beta¹ Capricorni is the brighter of the two components with an apparent magnitude of +3.05, while the dimmer Beta² Capricorni has an apparent magnitude of +6.09. The two components are separated by 3.5 arcminutes on the sky, putting them at least 21,000 AU (0.34 light-years) apart. They take approximately 700,000 years to complete one orbit.
{{chart/start}}{{chart|border=1| | | |,|- |S1| |S1=
Aa }}{{chart|border=0| | |,|(| |PA| |PA=Sep. = 0.05″ }}{{chart|border=1| | |!|!|, |S2| |S2=
Ab1 }}{{chart|border=0| | |!|`|( |PB| |PB=Period = 8.7d }}{{chart|border=1| |-|(| |` |S3| |S3=
Ab2 }}{{chart|border=0| | |!| | | | }}{{chart|border=1| | |!| |, |S4| |S4=
Ba }}{{chart|border=0| | |`|-|( |PC| |PC=Sep. = 3″ }}{{chart|border=1| | | | |` |S5| |S5=
Bb }}{{chart/end}}
Hierarchy of orbits in the β Capricorni system
Beta¹ Capricorni
Beta¹ Capricorni is the more complex of the pair and has a spectrum that is difficult to interpret. Its dominant pair of stars are the orange K-type bright giant Beta Capricorni Aa, with an apparent magnitude of +3.08, and the blue-white B-Type main sequence dwarf Beta Capricorni Ab1 with an apparent magnitude of +7.20. They are separated by 0.05 arcseconds (5 AU) and have an orbital period of 3.77 years.
The Aa component has a surface temperature of 4900 kelvins, a radius 35 times that of the Sun, and a luminosity 600 times that of the Sun. The Ab1 component's unseen companion, Beta Capricorni Ab2, orbits Ab1 with an orbital period of 8.7 days.
Beta¹ Capricorni is 4.6 degrees north of the ecliptic, so it can be occulted by the Moon.
Beta² Capricorni
Beta² Capricorni is simpler and more studied. Its brighter component, Beta Capricorni Ba, has a magnitude of 6.1 and is an A0-giant with 40 times the luminosity of the Sun. The companion, Beta Capricorni Bb, is approximately 3 arcseconds from Ba. Ba is unusual for having large amounts of mercury and manganese in its atmosphere.
Beta Capricorni D and E
These lie 112 arcseconds away from Beta¹ Capricorni.
References
1. ^{{cite web | url=http://www.ctio.noao.edu/~atokovin/stars/stars.php?cat=HIP&number=100345 | title=Displaying next number in catalog HIP => 100345 | work=Multiple Star Catalog | accessdate=2018-07-26}}
2. ^1 {{cite web | url=https://www.iau.org/public/themes/naming_stars/ | title=Naming Stars |publisher=IAU.org |accessdate=18 June 2018}}
3. ^{{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. }}
4. ^{{cite book | author=Allen, Richard Hinckley | author-link=Richard Hinckley Allen | date=1963 |origyear=1899 | title=Star Names: Their Lore and Meaning | page=140 | edition=Reprint | publisher=Dover Publications Inc. | location=New York, NY | url= http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/home.html | isbn=0-486-21079-0 }}
5. ^{{citation | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN) | publisher=International Astronomical Union | accessdate=22 May 2016 | postscript=. }}
6. ^{{cite web | url=https://www.iau.org/static/science/scientific_bodies/working_groups/280/wg-starnames-triennial-report-2015-2018.pdf | page=5 | title=WG Triennial Report (2015-2018) - Star Names |accessdate=2018-07-14}}
7. ^{{zh icon}} 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}}.
8. ^{{zh icon}} 香港太空館 - 研究資源 - 亮星中英對照表 {{webarchive|url=https://web.archive.org/web/20090929163750/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_c_d.htm |date=2009-09-29 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.
9. ^1 {{citation | title=A Catalog of Stellar Angular Diameters Measured by Lunar Occultation | last1=White | first1=Nathaniel M. | last2=Feierman | first2=Barry H. | journal=Astronomical Journal | postscript=. | volume=94 | page=751 | date=September 1987 | doi=10.1086/114513 | bibcode=1987AJ.....94..751W }}