View source for Astronomy:HD 197027

{{short description|Star in the constellation Capricornus}}
{{Starbox begin
| name=HD 197027 }}
{{starbox image
|image = [[File:HIP 102152.jpg|250px]]
|caption = HIP 102152
|credit = ESO/Digitized Sky Survey 2
}}
{{Starbox observe
 | epoch = [[Astronomy:J2000.0|J2000.0]] ([[Astronomy:International Celestial Reference System|ICRS]])
 | ra = {{RA|20|41|54.6336}}<ref name = EDR3/>
 | dec = {{DEC|-27|12|57.4154}}<ref name = EDR3/>
 | appmag_v = 9.15{{±|0.02}}<ref name = Tycho2000/>
 | constell = [[Astronomy:Capricornus|Capricornus]] 
}}
{{Starbox character
 | class = G3 V<ref name = Houk1982/>
 | u-b = +0.30<ref name = Paunzen2022/>
 | b-v = +0.65<ref name = Tycho2000/>
}}
{{Starbox astrometry
 | radial_v = −43.9{{±|0.3}}<ref name = Gontcharov2006/>
 | prop_mo_ra =	+175.628<ref name = EDR3/>
 | prop_mo_dec =  −15.593<ref name = EDR3/>
 | parallax = 12.7715
 | p_error = 0.0164
 | parallax_footnote = <ref name = EDR3/>
 | absmag_v= 4.74<ref name = Anderson2012/>
}}
{{Starbox detail
 | mass ={{nowrap|0.97}}<ref name=apj774/>
 | radius = 1.08{{±|0.07|0.05}}<ref name = Stassun2019/>
 | luminosity = 1.19<ref name = Anderson2012/>
 | temperature={{Val|5718|5}}<ref name=dosSantos2016/>
 | metal_fe = {{Val|−0.020|0.005}}<ref name=dosSantos2016/>
 | gravity={{Val|4.40|0.02}}<ref name=dosSantos2016/>
 | rotational_velocity={{Val|1.78|0.12}}<ref name=dosSantos2016/>
 | age_gyr={{Val|6.92|0.69}}<ref name=dosSantos2016/>
}}
{{Starbox catalog
 | names = {{odlist|CD = −27°14976|HIP = 102152|SAO = 189585|HD = 197027|CPD = −27°7079}}<ref name=SIMBAD/> 
}}
{{Starbox reference 
 | Simbad = HD+197027
}}
{{Starbox end}}

'''HD 197027''' (HIP 102152) is a [[Astronomy:Star|star]] in the [[Astronomy:Constellation|constellation]] [[Astronomy:Capricornus|Capricornus]]. It has an [[Astronomy:Apparent magnitude|apparent magnitude]] of 9.15,<ref name = Tycho2000/> making it readily visible through a [[Astronomy:Telescope|telescope]] but not to the [[Astronomy:Naked eye|naked eye]]. The object is located at a distance of  255 [[Light year|light year]]s but is approaching the [[Astronomy:Solar System|Solar System]] with a heliocentric [[Astronomy:Radial velocity|radial velocity]] of {{val|-44|ul=km/s}}.<ref name = Gontcharov2006/>

HD 197027 has a [[Astronomy:Stellar classification|stellar classification]] of G3 V, indicating that it is an ordinary [[Astronomy:G-type main-sequence star|G-type main-sequence star]] like the [[Astronomy:Sun|Sun]]. It has only 97% the mass of the Sun<ref name=apj774/> but 108% of its radius.<ref name = Stassun2019/> It shines at 119% the luminosity of the Sun<ref name = Anderson2012/> from its [[Astronomy:Photosphere|photosphere]] at an [[Astronomy:Effective temperature|effective temperature]] of 5,718 [[Kelvin|K]],<ref name=dosSantos2016/> similar to the Sun's 5,778 K. HD 197027's [[Astronomy:Metallicity|metallicity]] – elements heavier than [[Chemistry:Helium|helium]] – is similar to the Sun.<ref name=dosSantos2016/> At an older age of 6.92 [[Astronomy:Billion years|billion years]], it spins with a projected rotational velocity of about {{val|2|ul=km/s}}.<ref name=dosSantos2016/>

Since its measured properties of this star are very similar to those of the Sun, it has been considered a candidate older solar twin.<ref>[http://www.eso.org/public/images/eso1337a/ ESO, The life cycle of a Sun-like star (annotated)], from [[Organization:European Southern Observatory|European Southern Observatory]], 28 August 2013</ref> The abundances of 21 [[Chemistry:Chemical element|element]]s overall are more similar to the Sun than any other known solar twin. {{citation needed|date=May 2022}} Its Iron Abundance is -0.03 with an error value of 0.02 Fe/H. (The value comes from the Hipparcos Extended Catalog.)<ref>{{Cite web |date=10 January 2024 |title=HD 197027 Star Distance, Age, Colour and other Facts - Universe Guide |url=https://www.universeguide.com/star/102152/hd197027 |access-date=2024-01-19 |website=universeguide.com |language=en-us}}</ref>

== Age ==
[[File:The life cycle of a Sun-like star (annotated).jpg|thumb|left|300px|The age of HD 197027, here annotated as HIP 102152, shown relative to the Sun, the younger solar twin [[Astronomy:18 Scorpii|18 Scorpii]] and the formation of the Milky Way]]
{{clear left}}

== References ==
{{reflist|refs=

<ref name=apj774>{{cite journal | title=High Precision Abundances of the Old Solar Twin HIP 102152: Insights on Li Depletion from the Oldest Sun | author=Talawanda R. Monroe |display-authors=0 | journal=Astrophysical Journal Letters | volume=774 | issue=2  | pages=L32 |date=Aug 2013 | doi=10.1088/2041-8205/774/2/l32|arxiv = 1308.5744 |bibcode = 2013ApJ...774L..32M | s2cid=56111132 }}</ref>

<ref name=SIMBAD>{{cite simbad | title=HD 197027 | accessdate=2013-09-07 }}</ref>

<ref name=dosSantos2016>{{citation
 | title=The Solar Twin Planet Search. IV. The Sun as a typical rotator and evidence for a new rotational braking law for Sun-like stars
 | display-authors=1 | last1=dos Santos | first1=Leonardo A.
 | last2=Meléndez | first2=Jorge | last3=do Nascimento | first3=José-Dias
 | last4=Bedell | first4=Megan | last5=Ramírez | first5=Iván
 | last6=Bean | first6=Jacob L. | last7=Asplund | first7=Martin
 | last8=Spina | first8=Lorenzo | last9=Dreizler | first9=Stefan
 | last10=Alves-Brito | first10=Alan | last11=Casagrande | first11=Luca
 | journal=Astronomy & Astrophysics | postscript=.
 | volume=592 | id=A156 | pages=8 | date=August 2016
 | doi=10.1051/0004-6361/201628558 | bibcode=2016A&A...592A.156D |arxiv = 1606.06214 | s2cid=53533614 }}</ref>

<ref name = EDR3>{{Cite Gaia EDR3|6799090223510802176}}</ref>

<ref name = Tycho2000>{{cite journal |last1=Høg |first1=E. |last2=Fabricius |first2=C. |last3=Makarov |first3=V. V. |last4=Urban |first4=S. |last5=Corbin |first5=T. |last6=Wycoff |first6=G. |last7=Bastian |first7=U. |last8=Schwekendiek |first8=P. |last9=Wicenec |first9=A. |title=The Tycho-2 catalogue of the 2.5 million brightest stars |journal=Astronomy and Astrophysics |date=March 2000 |volume=355 |pages=L27–L30 |issn=0004-6361 |bibcode=2000A&A...355L..27H}}</ref>

<ref name = Houk1982>{{cite book|last1=Houk |first1=N. |title=Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Volume_3. Declinations -40_ƒ0 to -26_ƒ0. |date=1982 |bibcode= 1982mcts.book.....H}}</ref>

<ref name = Gontcharov2006>{{cite journal | last1 = Gontcharov | first1 = G. A. | title = Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system | journal = Astronomy Letters | date = November 2006 | volume = 32 | issue = 11 | pages = 759–771 | issn = 1063-7737 | eissn = 1562-6873 | doi = 10.1134/S1063773706110065 | pmid = | bibcode = 2006AstL...32..759G | arxiv = 1606.08053 | s2cid = 119231169 }}</ref>

<ref name = Anderson2012>{{cite journal |last1=Anderson |first1=E. |last2=Francis |first2=Ch. |title=XHIP: An extended hipparcos compilation |journal=Astronomy Letters |date=May 2012 |volume=38 |issue=5 |pages=331–346 |doi=10.1134/S1063773712050015 |language=en |issn=1063-7737 |bibcode=2012AstL...38..331A |arxiv=1108.4971|s2cid=255204555 }}</ref>

<ref name = Paunzen2022>{{cite journal | last1 = Paunzen | first1 = E. | title = Catalogue of stars measured in the Geneva seven-colour photometric system | journal = Astronomy & Astrophysics | date = May 2022 | volume = 661 | page = A89 | issn = 0004-6361 | eissn = 1432-0746 | doi = 10.1051/0004-6361/202142355 | pmid = | bibcode = 2022A&A...661A..89P | doi-access = free | arxiv = 2111.04810 }}</ref>

<ref name = Stassun2019>{{cite journal |display-authors=1 |last1=Stassun |first1=Keivan G. |last2=Oelkers |first2=Ryan J. |last3=Paegert |first3=Martin |last4=Torres |first4=Guillermo |last5=Pepper |first5=Joshua |last6=Lee |first6=Nathan De |last7=Collins |first7=Kevin |last8=Latham |first8=David W. |last9=Muirhead |first9=Philip S. |last10=Chittidi |first10=Jay |last11=Rojas-Ayala |first11=Bárbara |last12=Fleming |first12=Scott W. |last13=Rose |first13=Mark E. |last14=Tenenbaum |first14=Peter |last15=Ting |first15=Eric B. |last16=Kane |first16=Stephen R. |last17=Barclay |first17=Thomas |last18=Bean |first18=Jacob L. |last19=Brassuer |first19=C. E. |last20=Charbonneau |first20=David |last21=Ge |first21=Jian |last22=Lissauer |first22=Jack J. |last23=Mann |first23=Andrew W. |last24=McLean |first24=Brian |last25=Mullally |first25=Susan |last26=Narita |first26=Norio |last27=Plavchan |first27=Peter |last28=Ricker |first28=George R. |last29=Sasselov |first29=Dimitar |last30=Seager |first30=S. |last31=Sharma |first31=Sanjib |last32=Shiao |first32=Bernie |last33=Sozzetti |first33=Alessandro |last34=Stello |first34=Dennis |last35=Vanderspek |first35=Roland |last36=Wallace |first36=Geoff |last37=Winn |first37=Joshua N. |title=The Revised TESS Input Catalog and Candidate Target List |journal=The Astronomical Journal |date=9 September 2019 |volume=158 |issue=4 |pages=138 |doi=10.3847/1538-3881/ab3467 |issn=0004-6256 |bibcode=2019AJ....158..138S |arxiv=1905.10694 |doi-access=free}}</ref>

}}

== External links ==
*[http://www.eso.org/public/news/eso1337/ Oldest Solar Twin Identified]
*[http://www.eso.org/public/archives/releases/sciencepapers/eso1337/eso1337a.pdf HIGH PRECISION ABUNDANCES OF THE OLD SOLAR TWIN HIP 102152: INSIGHTS ON LI DEPLETION FROM THE OLDEST SUN]
*[http://www.eso.org/public/news/eso1337/ Oldest Solar Twin Identified]
{{Stars of Capricornus}}

{{DEFAULTSORT:HD 197027}}
[[Category:G-type main-sequence stars]]
[[Category:Durchmusterung objects]]
[[Category:Henry Draper Catalogue objects|197027]]
[[Category:Hipparcos objects|102152]]

{{Sourceattribution|HD 197027}}