View source for Gamma Hydri

{{Short description|Variable star in the constrellation Hydrus}}
{{Starbox begin
 | name = Gamma Hydri
}}
{{Starbox observe
 | epoch = [[J2000.0]]
 | equinox = [[J2000.0]] ([[International Celestial Reference System|ICRS]])
 | constell = [[Hydrus (constellation)|Hydrus]]
 | ra = {{RA|03|47|14.34062}}<ref name=vanLeeuwen2007/>
 | dec = {{DEC|−74|14|20.2686}}<ref name=vanLeeuwen2007/>
 | appmag_v = 3.26<ref name=Ducati2002/>
}}
{{Starbox character
 | class = M1&nbsp;III<ref name=houk1979/>
 | b-v = +1.62<ref name=Johnson1966/>
 | u-b = +1.98<ref name=Johnson1966/>
 | variable = 
}}
{{Starbox astrometry
 | radial_v = {{Val|+15.8|0.6}}<ref name=deBruijne2012/>
 | prop_mo_ra = +50.85<ref name=vanLeeuwen2007/>
 | prop_mo_dec = +114.74<ref name=vanLeeuwen2007/>
 | parallax = 15.24
 | p_error = 0.11
 | parallax_footnote = <ref name=vanLeeuwen2007/>
 | absmag_v = −0.83<ref name=Cardini2005/>
}}
{{Starbox detail
 | source = <ref name=Cruzalebes2013/>
 | mass = 1.0
 | radius = {{Val|62|1}}
 | luminosity = 513
 | temperature = 3499
 | gravity = 0.84
 | metal_fe = 0.0
 | rotational_velocity = 
 | age_myr = 
}}
{{Starbox catalog
 | names = {{odlist | B=γ&nbsp;Hyi | CD=−74°&nbsp;276 | FK5= | HD=24512 | HIP=17678 | HR=1208 | SAO=256029 }}<ref name=SIMBAD/>
}}
{{Starbox reference
 | Simbad = gam+Hyi
}}
{{Starbox end}}
'''γ Hydri''', Latinised as '''Gamma Hydri''', is a solitary,<ref name=Eggleton2008/> red-hued [[star]] in the [[constellation]] [[Hydrus (constellation)|Hydrus]]. It has an [[apparent visual magnitude]] of 3.26,<ref name=Ducati2002/> making it easily visible to the [[naked eye]] at night. Based upon an annual [[stellar parallax|parallax shift]] of 15.24&nbsp;[[milliarcsecond|mas]] as measured from Earth,<ref name=vanLeeuwen2007/> the system is located about 214&nbsp;[[light-year]]s from the [[Sun]].

This is an [[stellar evolution|evolved]] [[red giant]] star with a [[stellar classification]] of M1&nbsp;III,<ref name=houk1979/> and is most likely on the [[asymptotic giant branch]] of the [[HR diagram]].<ref name=eggen1992/> It is a [[semiregular variable]] that pulsates between magnitudes 3.26 and 3.33, although its period is not known precisely.<ref name=Tabur2009/> It has about the same [[solar mass|mass as the Sun]], but has expanded to around 62 times the [[Sun's radius]]. The star is radiating 513 times the [[Sun's luminosity]] from its enlarged [[photosphere]] at an [[effective temperature]] of {{val|3499|fmt=commas|ul=K}}.<ref name=Cruzalebes2013/>

==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=eggen1992>{{citation
 | title=Asymptotic giant branch stars near the sun
 | last1=Eggen | first1=O. J. | postscript=.
 | journal = The Astronomical Journal
 | volume=104| pages=275 | year=1992
 | doi=10.1086/116239 | bibcode=1992AJ....104..275E }}</ref>

<ref name=Johnson1966>{{citation | display-authors=1
 | last1=Johnson | first1=H. L. | last2=Iriarte | first2=B.
 | last3=Mitchell | first3=R. I. | last4=Wisniewskj | first4=W. Z.
 | title=UBVRIJKL photometry of the bright stars
 | journal=Communications of the Lunar and Planetary Laboratory
 | volume=4 | issue=99 | year=1966
 | page=99 | bibcode=1966CoLPL...4...99J | postscript=. }}</ref>

<ref name=houk1979>{{citation
 | title=Michigan catalogue of two-dimensional spectral types for the HD stars
 | volume=1 | last1=Houk | first1=Nancy | postscript=.
 | location=Ann Arbor, Michigan
 | publisher=Dept. of Astronomy, University of Michigan
 | year=1979 | bibcode=1978mcts.book.....H }}</ref>

<ref name=Eggleton2008>{{citation
 | 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=. }}</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=Cruzalebes2013>{{citation
 | title=Fundamental parameters of 16 late-type stars derived from their angular diameter measured with VLTI/AMBER
 | last1=Cruzalèbes | first1=P. | last2=Jorissen | first2=A.
 | last3=Rabbia | first3=Y. | last4=Sacuto | first4=S.
 | last5=Chiavassa | first5=A. | last6=Pasquato | first6=E.
 | last7=Plez | first7=B. | last8=Eriksson | first8=K.
 | last9=Spang | first9=A. | last10=Chesneau | first10=O.
 | journal=Monthly Notices of the Royal Astronomical Society
 | volume=434 | issue=1 | pages=437–450 | date=September 2013
 | doi=10.1093/mnras/stt1037 | doi-access=free | bibcode=2013MNRAS.434..437C
 | arxiv=1306.3288 | s2cid=49573767 | display-authors=1 | postscript=. }}</ref>

<ref name=Ducati2002>{{citation
 | title=VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system
 | journal=CDS/ADC Collection of Electronic Catalogues
 | last1=Ducati | first1=J. R.
 | volume=2237 | year=2002 | postscript=.
 | bibcode=2002yCat.2237....0D }}</ref>

<ref name=Tabur2009>{{citation
 | title=Long-term Photometry and Periods for 261 Nearby Pulsating M Giants
 | last1=Tabur | first1=V. | last2=Bedding | first2=T. R. | author2-link=Tim Bedding
 | last3=Kiss | first3=L. L. | last4=Moon | first4=T. T.
 | last5=Szeidl | first5=B. | last6=Kjeldsen | first6=H.
 | journal = Monthly Notices of the Royal Astronomical Society
 | volume=400 | issue=4 | pages=1945–61 | date=2009
 | doi=10.1111/j.1365-2966.2009.15588.x | doi-access=free | arxiv=0908.3228
 | bibcode=2009MNRAS.400.1945T | s2cid=15358380 | postscript=.  }}</ref>

<ref name=Cardini2005>{{citation
 | title=Mg II chromospheric radiative loss rates in cool active and quiet stars
 | last1=Cardini | first1=D. | postscript=.
 | journal=Astronomy and Astrophysics
 | volume=430 | pages=303–311 | date=January 2005
 | doi=10.1051/0004-6361:20041440 | bibcode=2005A&A...430..303C |arxiv = astro-ph/0409683 | s2cid=12136256 }}</ref>

<ref name=SIMBAD>{{cite simbad
 | title=gam Hyi | accessdate=2017-08-18 | postscript=. }}</ref>

}}

{{Stars of Hydrus|state=collapsed}}

{{DEFAULTSORT:Gamma Hydri}}
[[Category:M-type giants]]
[[Category:Semiregular variable stars]]
[[Category:Hydrus]]
[[Category:Bayer objects|Hydri, Gamma]]
[[Category:Durchmusterung objects]]
[[Category:Henry Draper Catalogue objects|024512]]
[[Category:Hipparcos objects|017678]]
[[Category:Bright Star Catalogue objects|1208]]
[[Category:Asymptotic-giant-branch stars]]