View source for Psi Hydrae

{{Short description|Binary star system in the constellation Hydra}}
{{Starbox begin
 | name = Psi Hydrae
}}
{{Starbox observe
 | epoch = [[J2000.0]]
 | equinox = [[J2000.0]] ([[International Celestial Reference System|ICRS]])
 | constell = [[Hydra (constellation)|Hydra]]
 | ra = {{RA|13|09|03.27026}}<ref name=vanLeeuwen2007/>
 | dec = {{DEC|−23|07|05.0501}}<ref name=vanLeeuwen2007/>
 | appmag_v = 4.97<ref name=Mermilliod1986/>
}}
{{Starbox character
 | class = K0&nbsp;III<ref name=houk1978/>
 | b-v = +1.05<ref name=Mermilliod1986/>
 | u-b = +0.95<ref name=Mermilliod1986/>
 | r-i = 
 | variable = 
}}
{{Starbox astrometry
 | radial_v = {{Val|−17.2|0.6}}<ref name=deBruijne2012/>
 | prop_mo_ra = −20.08<ref name=vanLeeuwen2007/>
 | prop_mo_dec = −39.81<ref name=vanLeeuwen2007/>
 | parallax = 14.09
 | p_error = 0.48
 | parallax_footnote = <ref name=vanLeeuwen2007/>
 | absmag_v = +0.54<ref name=McWilliam1990/>
}}
{{Starbox detail
 | source = 
 | mass = 
 | radius = 10.6<ref name=lang2006/>
 | luminosity = 56<ref name=Mcdonald2012/>
 | temperature = 4,680<ref name=McWilliam1990/>
 | gravity = 2.72<ref name=McWilliam1990/>
 | metal_fe = {{Val|−0.19|0.04}}<ref name=McWilliam1990/>
 | rotational_velocity = 
 | age_myr = 
}}
{{Starbox catalog
 | names = [[Bayer designation|ψ Hya]], [[Flamsteed designation|45 Hydrae]], [[Durchmusterung|BD]]−22°3515, [[Henry Draper Catalogue|HD]]&nbsp;114149, [[Hipparcos Catalogue|HIP]]&nbsp;64166, [[Harvard Revised catalogue|HR]]&nbsp;4958, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]]&nbsp;181410<ref name=SIMBAD/>
}}
{{Starbox reference
 | Simbad = psi+Hya
}}
{{Starbox end}}
'''Psi Hydrae''' ('''ψ Hydrae''') is a [[star system]] in the equatorial [[constellation]] of [[Hydra (constellation)|Hydra]]. Based upon an annual [[stellar parallax|parallax shift]] of 14.09&nbsp;[[milliarcsecond|mas]] as seen from Earth, it is located around 231&nbsp;[[light year]]s away from the [[Sun]]. It is faintly visible to the naked eye with an [[apparent magnitude]] of 4.97.<ref name=Mermilliod1986/>

==System==
This is a probable [[astrometric binary]] system.<ref name=Makarov2005/> The primary, component A, is an [[stellar evolution|evolved]] [[giant star]] with a [[stellar classification]] of K0&nbsp;III.<ref name=houk1978/> It is a [[red clump]] star that is generating energy through the fusion of helium at its core.<ref name=Alves2000/> The measured [[angular diameter]] is {{Val|1.39|0.02|u=[[milliarcsecond|mas]]}},<ref name=Richichi2005/> which, at the estimated distance of Psi Hydrae, yields a physical size of about 10.6 times the [[Solar radius|radius of the Sun]].<ref name=lang2006/> It is radiating 56<ref name=Mcdonald2012/> times the [[solar luminosity]] from its [[photosphere]] at an [[effective temperature]] of 4,680.&nbsp;K.<ref name=McWilliam1990/>

==Cultural significance==
The [[Kalapalo people]] of [[Mato Grosso]] state in Brazil called this star and [[Beta Hydrae|β Hya]] ''Kafanifani''.<ref name="basso87">{{cite book|last=Basso|first=Ellen B. |title=In Favor of Deceit: A Study of Tricksters in an Amazonian Society|publisher=University of Arizona Press|location=Tucson, Arizona|date=1987|page=[https://archive.org/details/infavorofdeceits0000bass/page/360 360]|isbn=0-8165-1022-9|url=https://archive.org/details/infavorofdeceits0000bass|url-access=registration}}</ref>

==References==
{{reflist|refs=

<ref name=vanLeeuwen2007>{{citation
 | 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=. }}</ref>

<ref name=Mcdonald2012>{{citation
 | 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 | year=2012 | postscript=.
 | bibcode=2012MNRAS.427..343M | arxiv=1208.2037
 | doi=10.1111/j.1365-2966.2012.21873.x | doi-access=free | s2cid=118665352 }}</ref>

<ref name=Makarov2005>{{citation
 | last1=Makarov | first1=V. V. | last2=Kaplan | first2=G. H.
 | title=Statistical Constraints for Astrometric Binaries with Nonlinear Motion
 | journal=The Astronomical Journal | postscript=.
 | volume=129 | issue=5 | pages=2420–2427 | date=May 2005
 | doi=10.1086/429590 | bibcode=2005AJ....129.2420M | doi-access=free }}</ref>

<ref name=Alves2000>{{citation
 | last1=Alves | first1=David R.
 | title=K-Band Calibration of the Red Clump Luminosity
 | journal=The Astrophysical Journal
 | volume=539 | issue=2 | pages=732–741 | date=August 2000
 | doi=10.1086/309278 | bibcode=2000ApJ...539..732A
 | arxiv=astro-ph/0003329 | s2cid=16673121
 | postscript=. }}</ref>

<ref name=McWilliam1990>{{citation
 | last1=McWilliam | first1=Andrew
 | title=High-resolution spectroscopic survey of 671 GK giants
 | journal=Astrophysical Journal Supplement Series
 | date=December 1990 | volume=74 | pages=1075–1128
 | bibcode=1990ApJS...74.1075M | doi=10.1086/191527
 | postscript=. | doi-access=free}}</ref>

<ref name=Richichi2005>{{citation
 | display-authors=1 | last1=Richichi | first1=A.
 | last2=Percheron | first2=I. | last3=Khristoforova | first3=M.
 | title=CHARM2: An updated Catalog of High Angular Resolution Measurements
 | journal=Astronomy and Astrophysics | postscript=.
 | volume=431 | pages=773–777 | date=February 2005
 | issue=2 | doi=10.1051/0004-6361:20042039 | bibcode=2005A&A...431..773R | doi-access=free }}</ref>

<ref name=lang2006>{{citation
 | first1=Kenneth R. | last1=Lang | title=Astrophysical formulae
 | volume=1 | series=Astronomy and astrophysics library | postscript=.
 | edition=3rd | publisher=[[Birkhäuser]] | date=2006 | isbn=3-540-29692-1
 | url=https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41
}} The radius (R<sub>*</sub>) is given by:
:<math>\begin{align} 2\cdot R_*
 & = \frac{(71.0\cdot 1.39\cdot 10^{-3})\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\
 & \approx 21.2\cdot R_{\bigodot}
\end{align}</math></ref>

<ref name=deBruijne2012>{{citation
 | 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=. }}</ref>

<ref name=houk1978>{{citation
 | last1=Houk | first1=Nancy | last2=Smith-Moore | first2=M.
 | title=Michigan catalogue of two-dimensional spectral types for the HD stars
 | volume=4 | location=Ann Arbor | year=1978
 | publisher=Dept. of Astronomy, University of Michigan
 | bibcode=1988mcts.book.....H | postscript=. }}</ref>

<ref name=Mermilliod1986>{{citation
 | last1=Mermilliod | first1=J.-C.
 | title=Compilation of Eggen's UBV data, transformed to UBV (unpublished)
 | journal=Catalogue of Eggen's UBV Data
 | year=1986 | publisher=[[SIMBAD]]
 | bibcode=1986EgUBV........0M | postscript=. }}</ref>

<ref name=SIMBAD>{{cite simbad
 | title=* psi Hya
 | access-date=2017-03-17 | postscript=. }}</ref>

}}

{{Stars of Hydra|state=collapsed}}

{{DEFAULTSORT:Psi Hydrae}}
[[Category:K-type giants]]
[[Category:Horizontal-branch stars]]
[[Category:Astrometric binaries]]
[[Category:Hydra (constellation)]]
[[Category:Bayer objects|Hydrae, Psi]]
[[Category:Durchmusterung objects|BD-22 3515]]
[[Category:Flamsteed objects|Hydrae, 45]]
[[Category:Henry Draper Catalogue objects|114149]]
[[Category:Hipparcos objects|064166]]
[[Category:Bright Star Catalogue objects|4958]]