Zeta Capricorni
{{short description|Star in the constellation Capricornus}}
{{Starbox begin}}
{{Starbox image
| image =
{{Location mark
| image=Capricornus IAU.svg
| float=center | width=240 | position=right
| mark=Red circle.svg | mark_width=10 | mark_link=ζ Cap
| x%=38.0 | y%=50.4
}}
| caption = Location of ζ Capricorni (circled)
}}
{{Starbox observe
| constell = Capricornus
| epoch = J2000
| dec = {{DEC|-22|24|40.8042}}
}}
{{Starbox character
| class = G4Ib: Ba2 + DA2.2
| variable = Suspected eclipsing binary
}}
{{Starbox astrometry
| parallax = 8.46
| p_error = 0.21
}}
{{Starbox orbit
| period_unitless = {{val|2378.2|u=days|fmt=commas}}
| axis_unitless = {{val|8.56|4.3|ul=mas}}
{{val|1.00|1.69|0.44|ul=AU}}
| inclination = {{val|111.7|20.7}}
| node = {{val|190.7|50.0}}
| periastron = {{val|2445996|ul=JD|fmt=commas}}
| eccentricity = 0.2821
| periarg = {{val|233.8|19.8}}
| K1 = {{val|4.41|8.05|1.53}}
}}
{{Starbox detail
| component1 = A
| temperature = {{val|5269|53|fmt=commas}}
| gravity = {{val|1.7|0.3}}
| metal_fe = −0.09
| luminosity = {{val|561|180|143}}
| mass = {{val|4.5|0.3|0.2}}
| age_gyr =
| component2 = B
| mass2 = 1.03
}}
{{Starbox catalog
| names = {{odlist | B=ζ Cap | F=34 Cap | CD=−22°15388 | HD=204075 | HIP=105881 | SAO=190341 | HR=8204 | GC=30020 | CCDM=J21267-2225AB | WD=2123-226 | WDS=J21267-2225AB | NSV=25596 }}
}}
{{Starbox reference
| Simbad = HD+204075
}}
{{Starbox end}}
Zeta Capricorni, Latinised from ζ Capricorni, is a binary star system in the southern constellation of Capricornus. It is visible to the naked eye with an apparent visual magnitude of 3.77. The system is located at a distance of approximately 386 light-years from the Sun based on parallax. It is drifting further away with a radial velocity of +2 km/s. The absolute magnitude of this system is −1.59.
Properties
The binary nature of this system was announced in 1980 by Erika Böhm-Vitense based on an ultraviolet excess attributed to a white dwarf companion. It is a single-lined spectroscopic binary system. Based on an incomplete orbital arc, the orbital period for this system is {{convert|2378.2|d|year|1|disp=out|abbr=off}} and the eccentricity (ovalness) is 0.28. It was flagged as a suspected eclipsing binary in 1988 due to observed variations in the light curve.
The primary, designated component A, has a stellar classification of G4Ib: Ba2. This notation indicates this is a yellow-hued supergiant star, although the ':' means there is some uncertainty about the class. The temperature and surface gravity of this object suggests it may be a horizontal-branch star. It is considered a prototypical example of a Barium star, as indicated by the 'Ba2' class suffix. The properties of these objects include overabundances of carbon molecules (such as C2) and s-process elements. Zeta Capricorni has an overabundance of the s-process element praseodymium.
Its companion, component B, is a carbon-oxygen white dwarf with a hydrogen-rich atmosphere and a class of DA2.2. It is about as massive as the Sun, and its temperature is {{val|23000|fmt=commas|ul=K}}. In the course of its evolution, the progenitor star passed through the thermally pulsing asymptotic giant branch, during which the enlarged atmosphere transferred material to the primary. The abundance of niobium in the primary's atmosphere, a product of the decay of zirconium-93, is at a level that suggests the transfer to the primary took place more than three million years ago.
A magnitude 12.5 visual companion was discovered by T. J. J. See in 1897. As of 1997, it was located at an angular separation of {{val|17.30|ul=arcsecond}} along a position angle of 12°.
Chinese name
In Chinese, {{lang|zh|十二國}} ({{lang|zh-Latn|Shíer Guó}}), meaning Twelve States, refers to an asterism which represents twelve ancient states in the Spring and Autumn period and the Warring States period, consisting of ζ Capricorni, φ Capricorni, ι Capricorni, 38 Capricorni, 35 Capricorni, 36 Capricorni, χ Capricorni, θ Capricorni, 30 Capricorni, 33 Capricorni, 19 Capricorni, 26 Capricorni, 27 Capricorni, 20 Capricorni, η Capricorni and 21 Capricorni. Consequently, the Chinese name for ζ Capricorni itself represents the state of Yan ({{lang|zh|燕}}), together with ν Ophiuchi in Left Wall of Heavenly Market Enclosure (asterism).
References
{{reflist|refs=
{{cite simbad|title=zet Cap|access-date=28 December 2016}}
| display-authors=1 | last1=Mason | first1=B. D.
| last2=Wycoff | first2=G. L. | last3=Hartkopf | first3=W. I.
| last4=Douglass | first4=G. G. | last5=Worley | first5=C. E.
| title=The Washington Visual Double Star Catalog
| year=2014 | volume=122 | issue=6 | pages=3466–3471
| journal=The Astronomical Journal
| bibcode=2001AJ....122.3466M
| doi=10.1086/323920 | doi-access=free }}
| title=Chemical abundances and kinematics of barium stars
| display-authors=1 | last1=de Castro | first1=D. B.
| last2=Pereira | first2=C. B. | last3=Roig | first3=F.
| last4=Jilinski | first4=E. | last5=Drake | first5=N. A.
| last6=Chavero | first6=C. | last7=Sales Silva | first7=J. V.
| journal=Monthly Notices of the Royal Astronomical Society
| volume=459 | issue=4 | pages=4299–4324 | date=July 2016
| arxiv=1604.03031 | bibcode=2016MNRAS.459.4299D
| doi=10.1093/mnras/stw815 | doi-access=free }}
| title=General catalogue of variable stars: Version GCVS 5.1
| last1=Samus' | first1=N. N | last2=Kazarovets | first2=E. V
| last3=Durlevich | first3=O. V | last4=Kireeva | first4=N. N
| last5=Pastukhova | first5=E. N | journal=Astronomy Reports
| volume=61 | issue=1 | pages=80 | year=2017
| bibcode=2017ARep...61...80S | s2cid=125853869
| doi=10.1134/S1063772917010085 }}
| title=Niobium and rubidium in the barium star zeta Capricorni.
| last1=Smith | first1=V. V. | last2=Lambert | first2=D. L.
| journal=Publications of the Astronomical Society of the Pacific
| volume=96 | pages=226–230 | date=March 1984
| bibcode=1984PASP...96..226S | doi=10.1086/131325 | s2cid=120973064 | doi-access=free }}
| title=A spectrum analysis of the bright barium star ZET Cap
| display-authors=1 | last1=Smith | first1=V. V.
| last2=Sneden | first2=C. | last3=Pilachowski | first3=C. A.
| journal=Publications of the Astronomical Society of the Pacific
| volume=92 | pages=809–818 | date=December 1980
| bibcode=1980PASP...92..809S | doi=10.1086/130755 | s2cid=121743938 | doi-access=free }}
| title=The Perkins catalog of revised MK types for the cooler stars
| last1=Keenan | first1=Philip C. | last2=McNeil | first2=Raymond C.
| journal=Astrophysical Journal Supplement Series
| volume=71 | pages=245 | year=1989
| doi=10.1086/191373 | bibcode=1989ApJS...71..245K }}
| title=Barium and related stars, and their white-dwarf companions. I. Giant stars
| display-authors=1 | last1=Jorissen | first1=A.
| last2=Boffin | first2=H. M. J. | last3=Karinkuzhi | first3=D.
| last4=Van Eck | first4=S. | last5=Escorza | first5=A.
| last6=Shetye | first6=S. | last7=Van Winckel | first7=H.
| journal=Astronomy & Astrophysics
| volume=626 | id=A127 | pages=28 | date=June 2019
| arxiv=1904.03975 | bibcode=2019A&A...626A.127J
| doi=10.1051/0004-6361/201834630 | s2cid=102351666 }}
| title=The white dwarf companion of the barium star ZET Cap
| last=Boehm-Vitense | first=E.
| journal=Astrophysical Journal
| volume=239 | pages=L79–L83 | date=July 1980
| bibcode=1980ApJ...239L..79B | doi=10.1086/183296 | doi-access=free }}
| title=Eclipsing Binary Signatures in zeta Capricorni
| last=Srivastava | first=R. K.
| journal=Information Bulletin on Variable Stars
| volume=3217 | page=1 | date=July 1988
| bibcode=1988IBVS.3217....1S }}
| title=To Ba or not to Ba: Enrichment in s-process elements in binary systems with WD companions of various masses
| display-authors=1 | last1=Merle | first1=T.
| last2=Jorissen | first2=A. | last3=Van Eck | first3=S.
| last4=Masseron | first4=T. | last5=Van Winckel | first5=H.
| journal=Astronomy & Astrophysics
| volume=586 | id=A151 | pages=16 | date=February 2016
| arxiv=1510.05908 | bibcode=2016A&A...586A.151M
| doi=10.1051/0004-6361/201526944 | s2cid=119224869 }}
| title=Where are all the Sirius-like binary systems?
| display-authors=1 | last1=Holberg | first1=J. B.
| last2=Oswalt | first2=T. D. | last3=Sion | first3=E. M.
| last4=Barstow | first4=M. A. | last5=Burleigh | first5=M. R.
| journal=Monthly Notices of the Royal Astronomical Society
| volume=435 | issue=3 | pages=2077 | year=2013
| bibcode=2013MNRAS.435.2077H | arxiv=1307.8047
| doi=10.1093/mnras/stt1433 | doi-access=free }}
| title=Validation of the new Hipparcos reduction
| last1=van Leeuwen | first1=F.
| journal=Astronomy and Astrophysics
| volume=474 | issue=2 | pages=653–664 | date=2007
| arxiv=0708.1752 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357
| s2cid=18759600 }} [http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/311/hip2&recno=14774 Vizier catalog entry ]
| last1=Mermilliod | first1=J.-C.
| title=Compilation of Eggen's UBV data, transformed to UBV (unpublished)
| journal=Catalogue of Eggen's UBV Data. SIMBAD
| date=1986 | bibcode=1986EgUBV........0M}}
| 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 | arxiv=1108.4971
| doi=10.1134/S1063773712050015 | s2cid=119257644 }}
| title=Re-processing the Hipparcos Transit Data and Intermediate Astrometric Data of spectroscopic binaries. I. Ba, CH and Tc-poor S stars
| last=Pourbaix | first=D.
| journal=Astronomy and Astrophysics Supplement
| volume=145 | pages=161–183 | date=2000
| bibcode=2000A&AS..145..161P | arxiv=astro-ph/0006175
| doi=10.1051/aas:2000346 | s2cid=15990458 }}
| first=James B. | last=Kaler | author-link=James B. Kaler
| title=ZETA CAP (Zeta Capricorni) | work=Stars
| url=http://stars.astro.illinois.edu/sow/zetacap.html
| access-date=30 December 2016 }}
{{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}}.
}}
{{Stars of Capricornus}}
{{DEFAULTSORT:Zeta Capricorni}}
Category:Horizontal-branch stars