View source for 98 Aquarii

{{Starbox begin
 | name=Chi Aquarii
}}
{{Starbox image
 | image = 
     <div style="position: relative">[[File:Aquarius IAU.svg|250px|alt=Diagram showing star positions and boundaries of the Aquarius constellation and its surroundings]]
     <div style="position: absolute; left: 28.9%; top: 39.8%">[[File:Cercle rouge 100%.svg|12px]]</div>
     </div>
 | caption = Location of χ Aquarii (circled)
}}
{{Starbox observe
 | epoch       = J2000
 | ra          = {{RA|23|16|50.93916}}<ref name=aaa474_2_653/>
 | dec         = {{DEC|−07|43|35.4023}}<ref name=aaa474_2_653/>
 | appmag_v    = +5.06<ref name=aass34_1/>
 | constell    = [[Aquarius (constellation)|Aquarius]]
}}
{{Starbox character
 | class       = M3&nbsp;III<ref name=mnras162_11/>
 | b-v         = +1.60<ref name=aass34_1/>
 | u-b         = +1.60<ref name=aass34_1/>
 | variable    = [[Semiregular variable star|Semi-regular]]<ref name=mnras400_4_1945/>
}}
{{Starbox astrometry
 | radial_v    = {{nowrap|–13.72 ± 0.86}}<ref name=aaa498_2_627/>
 | prop_mo_ra  = −19.18<ref name=aaa474_2_653/>
 | prop_mo_dec = −14.10<ref name=aaa474_2_653/>
 | parallax    = 5.32
 | p_error     = 0.37
 | parallax_footnote = <ref name=aaa474_2_653/>
 | absmag_v    = 
}}
{{Starbox detail
 | mass        = 
 | radius      = 137<ref name=lang2006/>
 | luminosity  = 
 | temperature = 
 | metal_fe    = 
 | rotational_velocity = 
 | age_myr     =
}}
{{Starbox catalog
 | names = 92&nbsp;Aquarii, [[Durchmusterung|BD]]−08&nbsp;6076, [[Henry Draper Catalogue|HD]]&nbsp;219576, [[Hipparcos catalogue|HIP]]&nbsp;114939, [[Bright Star Catalogue|HR]]&nbsp;8850, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]]&nbsp;146612.<ref name=SIMBAD/>
}}
{{starbox sources|HIP|CCDM|HR}}
{{Starbox end}}

'''Chi Aquarii''' (χ Aqr, χ Aquarii) is the [[Bayer designation]] of a [[star]] in the [[celestial equator|equatorial]] [[constellation]] of [[Aquarius (constellation)|Aquarius]]. The distance to this star, based upon [[parallax]] measurements with a 7% [[margin of error]], is roughly {{Convert|610|ly|pc|abbr=off|lk=on}}.<ref name=aaa474_2_653/> It is visible to the naked eye with an [[apparent visual magnitude]] of +5.06.<ref name=aass34_1/>

This is a [[red giant]] star with a [[stellar classification|spectral classification]] of M3&nbsp;III.<ref name=mnras162_11/> The [[interferometry]]-measured [[angular diameter]] of this star is {{nowrap|6.70 ± 0.15 [[milliarcseconds|mas]]}},<ref name=aaa431_773/> which, at its estimated distance, equates to a physical radius of about 137 times the [[Solar radius|radius of the Sun]].<ref name=lang2006/> It is classified as a [[semi-regular variable]] star and its brightness varies by an amplitude of 0.0636 in magnitude.<ref name=mnras331_1_45/> The identified pulsation periods are 32.3, 38.5, and 44.9 days.<ref name=mnras400_4_1945/>

==References==
{{reflist|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 | postscript=. |arxiv = 0708.1752 }}</ref>

<ref name=mnras162_11>{{citation | last1=Crampton | first1=D. | last2=Lloyd Evans | first2=T. | title=Spectroscopic observations of M giant stars at the South Galactic Pole | journal=Monthly Notices of the Royal Astronomical Society | volume=162 | pages=11–15 | year=1973 | bibcode=1973MNRAS.162...11C | postscript=. }}</ref>

<ref name=aaa498_2_627>{{citation | display-authors=1 | last1=Famaey | first1=B. | last2=Pourbaix | first2=D. | last3=Frankowski | first3=A. | last4=van Eck | first4=S. | last5=Mayor | first5=M. | last6=Udry | first6=S. | last7=Jorissen | first8=A. | title=Spectroscopic binaries among Hipparcos M giants. I. Data, orbits, and intrinsic variations | journal=Astronomy and Astrophysics | volume=498 | issue=2 | pages=627–640 |date=May 2009 | doi=10.1051/0004-6361/200810698 | bibcode=2009A&A...498..627F | postscript=. |arxiv = 0901.0934 }}</ref>

<ref name=aass34_1>{{citation | last1=Nicolet | first1=B. | year=1978 | title=Photoelectric photometric Catalogue of homogeneous measurements in the UBV System | journal=Astronomy and Astrophysics Supplement Series | volume=34 | pages=1–49 | bibcode=1978A&AS...34....1N | postscript=. }}</ref>

<ref name=mnras400_4_1945>{{citation | display-authors=1 | last1=Tabur | first1=V. | last2=Bedding | first2=T. R. | last3=Kiss | first3=L. L. | last4=Moon | first4=T. T. | last5=Szeidl | first5=B. | last6=Kjeldsen | first6=H. | title=Long-term photometry and periods for 261 nearby pulsating M giants | journal=Monthly Notices of the Royal Astronomical Society | volume=400 | issue=4 | pages=1945–1961 |date=December 2009 | doi=10.1111/j.1365-2966.2009.15588.x | bibcode=2009MNRAS.400.1945T | postscript=. |arxiv = 0908.3228 }}</ref>

<ref name=SIMBAD>{{citation | title=chi Aqr -- Semi-regular pulsating Star  | work=SIMBAD | publisher=Centre de Données astronomiques de Strasbourg | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Chi+Aquarii | accessdate=2012-07-05 | postscript=. }}</ref>

<ref name=aaa431_773>{{citation | last1=Richichi | pages=A. | last2=Percheron | first2=I. | last3=Khristoforova | first3=M. | title=CHARM2: An updated Catalog of High Angular Resolution Measurements | journal=Astronomy and Astrophysics | volume=431 | pages=773–777 |date=February 2005 | doi=10.1051/0004-6361:20042039 | bibcode=2005A&A...431..773R | postscript=. }}</ref>

<ref name=lang2006>{{citation | first1=Kenneth R. | last1=Lang | title=Astrophysical formulae | volume=1 | series=Astronomy and astrophysics library | edition=3 | publisher=Birkhäuser | year=2006 | isbn=3-540-29692-1 | url=http://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41 }}. The radius (R<sub>*</sub>) is given by:
:<math>\begin{align} 2\cdot R_*
 & = \frac{((190\cdot 6.70\cdot 10^{-3})\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\
 & \approx 274\cdot R_{\bigodot}
\end{align}</math></ref>

<ref name=mnras331_1_45>{{citation | last1=Koen | first1=Chris | last2=Eyer | first2=Laurent | title=New periodic variables from the Hipparcos epoch photometry | journal=Monthly Notices of the Royal Astronomical Society | volume=331 | issue=1 | pages=45–59 |date=March 2002 | doi=10.1046/j.1365-8711.2002.05150.x | bibcode=2002MNRAS.331...45K |arxiv = astro-ph/0112194 | postscript=. }}</ref>

}}

==External links==
* [http://aladin.u-strasbg.fr/AladinPreview?-c=23+16+50.9395-07+43+35.413&ident=V*+chi+Aqr&submit=Aladin+previewer Image Chi Aquarii]

{{Stars of Aquarius}}

[[Category:Henry Draper Catalogue objects]]
[[Category:Bayer objects|Aquarii, Chi]]
[[Category:Aquarius (constellation)]]
[[Category:Irregular variables]]
[[Category:M-type giants]]
[[Category:Flamsteed objects|Aquarii, 92]]