kappa Hydrae
{{Short description|Star in the constellation Hydra}}
{{Starbox begin
| name = κ Hydrae
}}
{{Starbox observe
| epoch = J2000.0
| constell = Hydra
| dec = {{DEC|−14|19|56.2675}}
}}
{{Starbox character
| r-i =
}}
{{Starbox astrometry
| parallax = 7.48
| p_error = 0.30
}}
{{Starbox detail
| source =
| temperature = {{Val|16150|920|fmt=commas}}
| gravity =
| metal_fe =
}}
{{Starbox catalog
| names = κ Hya, 38 Hydrae, BD−13° 2917, FK5 364, HD 83754, HIP 47452, HR 3849, SAO 155388.
}}
{{Starbox reference
| Simbad = kap+Hya
}}
{{starbox end}}
κ Hydrae, Latinised as Kappa Hydrae, is a solitary star in the equatorial constellation of Hydra. Its apparent visual magnitude is 5.06, which is bright enough to be faintly visible to the naked eye. The distance to this star is around {{convert|440|ly|pc|order=flip|abbr=on|0}}, based upon an annual parallax shift of 7.48 mas. It may be a variable star, meaning it undergoes repeated fluctuations in brightness by at least 0.1 magnitude.
This is an evolving B-type star with a stellar classification of B4 IV/V, having a luminosity class intermediate between a subgiant and a giant star. It has an estimated five times the mass of the Sun and 3.4 times the Sun's radius. Kappa Hydrae has a high rate of spin with a projected rotational velocity of 115.0 km/s, and is only about 31 million years old. The star radiates 328 times the solar luminosity from its outer atmosphere at an effective temperature of 16,150 K.
Name
This star was one of the set assigned by the 16th century astronomer Al Tizini{{cite web | url=http://www.muslimheritage.com/article/arabic-roots-scientific-revolution | author=Rim Turkmani | title=Arabic Roots of the Scientific Revolution | website=Muslim Heritage | date=7 July 2011 | access-date=1 July 2016}} to Al Sharāsīf (ألشراسيف), the Ribs (of Hydra), which included the stars from β Crateris westward through κ Hydrae.[https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Crater*.html Star Names - R.H.Allen p. 182][https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Hydra*.html Star Names - R.H.Allen p. 246]
According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Sharāsīf were the title for two stars : β Crateris as Al Sharasīf II and κ Hydrae as Al Sharasīf I.{{citation | url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19720005197_1972005197.pdf | first1=Jack W. | last1=Rhoads | title=Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars | publisher=Jet Propulsion Laboratory, California Institute of Technology | date=November 15, 1971 | postscript=. }}
In Chinese, {{lang|zh|張宿}} ({{lang|zh-Latn|Zhāng Xiù}}), meaning Extended Net, refers to an asterism consisting of Kappa Hydrae, Upsilon1 Hydrae, Lambda Hydrae, Mu Hydrae, HD 87344, and Phi1 Hydrae.{{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}}. Consequently, Kappa Hydrae itself is known as {{lang|zh|張宿五}} ({{lang|zh-Latn|Zhāng Xiù wǔ}}), "the Fifth Star of Extended Net".{{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.
References
{{reflist|refs=
| 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 | postscript=. }}
| title=Absolute magnitudes of B emission line stars - Correlation between the luminosity excess and the effective temperature
| last1=Zorec | first1=J. | last2=Briot | first2=D.
| journal=Astronomy and Astrophysics
| volume=245 | issue=1 | date=May 1991 | pages=150–170
| bibcode=1991A&A...245..150Z | postscript=. }}
| title=List of 333 variable, microvariable or suspected variable stars detected in the Geneva photometry
| last1=Rufener | first1=F. | last2=Bartholdi | first2=P.
| journal=Astronomy and Astrophysics Supplement Series
| volume=48 | date=June 1982 | pages=503–511
| bibcode=1982A&AS...48..503R | postscript=. }}
| display-authors=1
| last1=Pasinetti Fracassini | first1=L. E. | last2=Pastori | first2=L.
| last3=Covino | first3=S. | last4=Pozzi | first4=A.
| title=Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)
| journal=Astronomy and Astrophysics | edition=3rd
| volume=367 | pages=521–524 |date=February 2001
| doi=10.1051/0004-6361:20000451 | bibcode=2001A&A...367..521P
| arxiv=astro-ph/0012289 | s2cid=425754 | postscript=. }}
| title=General Catalogue of Variable Stars
| last1=Samus | first1=N. N. | last2=Durlevich | first2=O. V.
| journal=VizieR Online Data Catalog | display-authors=etal | date=2009 | volume=1
| bibcode=2009yCat....102025S | postscript=. }}
| 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 | bibcode=2008MNRAS.389..869E
| arxiv=0806.2878 | s2cid=14878976 | postscript=. }}
| display-authors=1 | last1=McDonald | first1=I.
| last2=Zijlstra | first2=A. A. | last3=Boyer | first3=M. L.
| title=Fundamental Parameters and Infrared Excesses of Hipparcos Stars
| journal=Monthly Notices of the Royal Astronomical Society
| volume=427 | issue=1 | pages=343–57 | date=2012
| bibcode=2012MNRAS.427..343M | doi=10.1111/j.1365-2966.2012.21873.x
| doi-access=free | arxiv=1208.2037 | s2cid=118665352 | postscript=. }}
| last1=Soubiran | first1=C. | last2=Le Campion | first2=J.-F.
| last3=Cayrel de Strobel | first3=G. | last4=Caillo | first4=A.
| title=The PASTEL catalogue of stellar parameters
| journal=Astronomy and Astrophysics | display-authors=1
| volume=515 | page=A111 | date=June 2010
| doi=10.1051/0004-6361/201014247 | bibcode=2010A&A...515A.111S
| postscript=. | arxiv=1004.1069 | s2cid=118362423 }}
| last1=Tetzlaff | first1=N. | last2=Neuhäuser | first2=R. | last3=Hohle | first3=M. M.
| title=A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun
| journal=Monthly Notices of the Royal Astronomical Society
| volume=410 | issue=1 | pages=190–200 | date=January 2011
| doi=10.1111/j.1365-2966.2010.17434.x | doi-access=free | bibcode=2011MNRAS.410..190T
| arxiv=1007.4883 | s2cid=118629873 | display-authors=1 | postscript=. }}
| last1=de Bruijne | first1=J. H. J. | last2=Eilers | first2=A.-C.
| title=Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project
| journal=Astronomy & Astrophysics
| volume=546 | id=A61 | pages=14 | date=October 2012
| doi=10.1051/0004-6361/201219219 | bibcode=2012A&A...546A..61D
| arxiv=1208.3048 | s2cid=59451347 | postscript=. }}
| last1=Nicolet | first1=B.
| title=Catalogue of homogeneous data in the UBV photoelectric photometric system
| journal=Astronomy and Astrophysics Supplement Series
| volume=34 | pages=1–49 |date=October 1978
| bibcode=1978A&AS...34....1N | postscript=. }}
| display-authors=1 | last1=Abt | first1=Helmut A.
| last2=Levato | first2=Hugo | last3=Grosso | first3=Monica
| title=Rotational Velocities of B Stars
| journal=The Astrophysical Journal | postscript=.
| volume=573 | issue=1 | pages=359–365 | date=July 2002
| doi=10.1086/340590 | bibcode=2002ApJ...573..359A | doi-access=free }}
| title=kap Hya
| access-date=2017-01-05 }}
}}
{{Stars of Hydra|state=collapsed}}
{{DEFAULTSORT:Kappa Hydrae}}
Category:B-type main-sequence stars
Category:Hydra (constellation)