HIP 56948

{{Short description|Star in the constellation Draco}} {{Starbox begin}} {{Starbox observe | epoch = J2000 | constell = [[Draco (constellation)|Draco]]<ref name=xhip/> | ra = {{RA|11|40|28.48394}}<ref name=dr3/> | dec = {{DEC|+69|00|30.5978}}<ref name=dr3/> | appmag_v = 8.67<ref name=xhip/> }} {{Starbox character | type = [[main sequence]]<ref name=dr3/> | class = G5V<ref name=vazquez_et_al_2010/> | b-v = {{val|0.647|0.014}}<ref name=aaa474_2_653/> }} {{Starbox astrometry | radial_v = +5.4<ref name=aaa418_989/> | prop_mo_ra = −126.843<ref name=dr3/> | prop_mo_dec = −2.470<ref name=dr3/> | parallax = 16.7935 | p_error = 0.0139 | parallax_footnote = <ref name=dr3/> | absmag_v = +4.65<ref name=xhip/> }} {{Starbox detail | mass = 0.98<ref name=hu2023/> | radius = 0.99<ref name=hu2023/> | luminosity = 1.01<ref name=hu2023/> | temperature = 5,774<ref name=hu2023/> | metal_fe = 0.02<ref name=pasj61_3_471/> | gravity = 4.409<ref name=pasj61_3_471/> | rotational_velocity = 1.0<ref name=marsden2014/> | age_gyr={{nowrap|~7.1}}<ref name=aaa2018 /> }} {{Starbox catalog | names=[[Henry Draper Catalogue|HD]] 101364, [[Star catalogue#BD.2FCD.2FCPD|BD]]+69 620, [[Smithsonian Astrophysical Observatory|SAO]] 15590. }} {{Starbox reference | Simbad = HIP+56948  }} {{Starbox end}}

'''HIP 56948''' (also known as '''HD 101364''') is a [[solar analog|solar twin]] star of type [[stellar classification|G5V]].<ref name=vazquez_et_al_2010/> It is one of the most Sun-like stars yet known in terms of size, mass, temperature, and chemical makeup. The Sun is about 4.6 billion years old, and HIP 56948 is believed to be about 7.1 billion years old. Both stars are between a third and a halfway through their life on the [[main sequence]].<ref name=aaa2018 /><ref name="hip"> {{cite journal | last = Meléndez | first = Jorge | author2=Iván Ramírez | date =2007 | title = HIP 56948: A Solar Twin with a Low Lithium Abundance (abstract) | journal = [[Astrophysical Journal Letters]] | volume = 669 | issue = 2| page = L89 | doi = 10.1086/523942 | bibcode=2007ApJ...669L..89M |arxiv = 0709.4290 | s2cid = 15952981 }}</ref>

[[Image:Sun parts big.jpg|thumb|left|Cross-section of a solar-type star ([[NASA]])]] It is 208 [[light years]] away in the constellation of [[Draco (constellation)|Draco]],<ref> {{cite web | last = Shiga | first = David | date = 2007-10-03 | title = Sun's 'twin' an ideal hunting ground for alien life | url = https://www.newscientist.com/article/dn12725 | work = [[New Scientist]] | access-date = 2009-05-28 }}</ref> lying about halfway between [[Polaris]] and [[Dubhe]] on the celestial sphere.<ref>[https://web.archive.org/web/20100909202924/http://www.telegraph.co.uk/science/space/7808214/Night-Sky-in-June-2010.html The Telegraph], retrieved 5 November 2010.</ref> Astronomers have looked for planets in the system, so far without finding any. These observations suggest that the star does not have any [[hot Jupiter]]s.<ref>[https://www.newscientist.com/article/dn12725 New Scientist], retrieved 5 October 2009.</ref>

[[Jorge Meléndez (astronomer)|Jorge Meléndez]] of the [[Australian National University]] and [[Iván Ramírez (astronomer)|Iván Ramírez]] of the [[University of Texas]] analysed the star in 2007 using the 2.7 metre [[Harlan J. Smith telescope]] at [[McDonald Observatory]].<ref> {{cite web | date = 2007-11-13 | title = Light of the Dragon: Astronomers Discover Sun's Twin at McDonald Observatory | url = http://www.astrobio.net/news/modules.php?op=modload&name=News&file=article&sid=2522 | work = [[Astrobiology Magazine]] | access-date = 2009-05-28 }}</ref>

Most other solar analogs such as [[18 Scorpii]] are unlike the Sun in that they have several times the [[lithium]] abundance. HIP 56948 is among the best candidates for a [[solar twin]] because of the known possible contenders, its lithium abundance most resembles that of the Sun.<ref name=pasj61_3_471/><ref> {{cite web | last = Mosher | first = Dave | date = 2007-11-09 | title = Astronomers find the sun's long-lost twin: Happy reunion unlikely, as the star is about 200 light-years away | url = http://www.nbcnews.com/id/21714413 | publisher = [[NBC News]] | access-date = 2009-05-28 }}{{dead link|date=August 2024|bot=medic}}{{cbignore|bot=medic}}</ref> A 2009 high-dispersion spectroscopic study from the Astronomical Society of Japan confirms this.<ref name=pasj61_3_471/>

In the abstract to their paper, the star's discoverers say:<ref name="hip" />

{{quote|For more than a decade, [[18 Scorpii|18 Sco]] (HD 146233) has been considered the star that most closely resembles the [[Sun]], even though significant differences such as its [[lithium|Li]] content, which is about 3 times solar, exist. Using high-resolution, high-S/N spectra obtained at [[McDonald Observatory]], we show that the stars HIP 56948 and [[HD 133600|HIP 73815]] are very similar to the Sun in both stellar parameters and chemical composition, including a low Li abundance, which was previously thought to be peculiar in the Sun. HIP 56948, in particular, has stellar parameters identical to solar within the observational uncertainties, being thus the best [[solar twin]] known to date. HIP 56948 is also similar to the Sun in its lack of [[hot Jupiter]]s. Considering the age of this star (~1 ± 1 Gyr older than the Sun){{#tag:ref|The star's age estimate has been revised several times in different studies, most recently (as of February 2020) to 7.1 Gyr.<ref name=aaa2018 />|group="Notes"}} and its location and orbit around the [[Milky Way Galaxy|Galaxy]], if [[terrestrial planet]]s exist around it, they may have had enough time to develop complex life, making it a prime target for [[SETI]].|Jorge Meléndez and Iván Ramírez, 8 October 2007}}

==See also== *[[Planetary habitability]] *[[Rare Earth hypothesis]]

==Notes== {{Reflist|group="Notes"}}

==References== {{Reflist|refs=

<ref name=marsden2014>{{cite journal |last1=Marsden |first1=S. C. |last2=Petit |first2=P. |last3=Jeffers |first3=S. V. |last4=Morin |first4=J. |last5=Fares |first5=R. |last6=Reiners |first6=A. |last7=Do Nascimento |first7=J. -D. |last8=Aurière |first8=M. |last9=Bouvier |first9=J. |last10=Carter |first10=B. D. |last11=Catala |first11=C. |last12=Dintrans |first12=B. |last13=Donati |first13=J. -F. |last14=Gastine |first14=T. |last15=Jardine |first15=M. |last16=Konstantinova-Antova |first16=R. |last17=Lanoux |first17=J. |last18=Lignières |first18=F. |last19=Morgenthaler |first19=A. |last20=Ramìrez-Vèlez |first20=J. C. |last21=Théado |first21=S. |last22=Van Grootel |first22=V. |author23=BCool Collaboration |title=A BCool magnetic snapshot survey of solar-type stars |journal=Monthly Notices of the Royal Astronomical Society |date=2014 |volume=444 |issue=4 |page=3517 |doi=10.1093/mnras/stu1663 |doi-access=free |arxiv=1311.3374 |bibcode=2014MNRAS.444.3517M }}</ref>

<ref name=hu2023>{{cite journal |last1=Hardegree-Ullman |first1=Kevin K. |last2=Apai |first2=Dániel |last3=Bergsten |first3=Galen J. |last4=Pascucci |first4=Ilaria |last5=López-Morales |first5=Mercedes |title=Bioverse: A Comprehensive Assessment of the Capabilities of Extremely Large Telescopes to Probe Earth-like O<SUB>2</SUB> Levels in Nearby Transiting Habitable-zone Exoplanets |journal=The Astronomical Journal |date=2023 |volume=165 |issue=6 |page=267 |doi=10.3847/1538-3881/acd1ec |doi-access=free |arxiv=2304.12490 |bibcode=2023AJ....165..267H }}</ref>

<ref name=aaa474_2_653>{{cite journal | 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 |arxiv = 0708.1752 | s2cid=18759600 }}[http://vizier.cfa.harvard.edu/viz-bin/VizieR-5?-ref=VIZ56aafaa66eee&-out.add=.&-source=I/311/hip2&recno=56763 Vizier catalog entry ]</ref>

<ref name=aaa418_989>{{cite journal | title=The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14 000 F and G dwarfs | display-authors=1 | last1=Nordström | first1=B. | last2=Mayor | first2=M. | last3=Andersen | first3=J. | last4=Holmberg | first4=J. | last5=Pont | first5=F. | last6=Jørgensen | first6=B. R. | last7=Olsen | first7=E. H. | last8=Udry | first8=S. | last9=Mowlavi | first9=N. | journal=Astronomy and Astrophysics | volume=418 | pages=989–1019 |date=May 2004 | doi=10.1051/0004-6361:20035959 | bibcode=2004A&A...418..989N |arxiv = astro-ph/0405198 | issue=3 | s2cid=11027621 }}</ref>

<ref name=vazquez_et_al_2010>{{cite book |author1=Vázquez, M. |author2=Pallé, E. |author3=Rodríguez, P. Montañés | chapter=Is Our Environment Special? | date=2010 | pages=[https://archive.org/details/earthasdistantpl00vazq/page/n405 391]–418 | title=The Earth as a Distant Planet: A Rosetta Stone for the Search of Earth-Like Worlds |url=https://archive.org/details/earthasdistantpl00vazq |url-access=limited | series=Astronomy and Astrophysics Library | publisher=Springer New York | doi=10.1007/978-1-4419-1684-6 | isbn=978-1-4419-1683-9 }} See table 9.1.</ref>

<ref name=pasj61_3_471>{{cite journal | last1=Takeda | first1=Yoichi | last2=Tajitsu | first2=Akito | title=High-Dispersion Spectroscopic Study of Solar Twins: HIP 56948, HIP 79672, and HIP 100963 | journal=Publications of the Astronomical Society of Japan | volume=61 | issue=3 | pages=471–480 |date=June 2009 | bibcode=2009PASJ...61..471T |arxiv = 0901.2509 | doi=10.1093/pasj/61.3.471}}</ref>

<ref name=aaa2018>{{cite journal | author=M. Mittag | author2=K.-P. Schröder | author3=A. Hempelmann | author4=J.N. González-Pérez | author5=J.H.M.M. Schmitt | name-list-style=amp | title= Chromospheric activity and evolutionary age of the Sun and foursolar twins | journal=[[Astronomy & Astrophysics]] | date= 3 September 2018 | volume= 591 | pages= A89 | doi= 10.1051/0004-6361/201527542 | arxiv = 1607.01279v1| s2cid=54765864 }}</ref>

}}

[[Category:Draco (constellation)]] [[Category:G-type main-sequence stars]] [[Category:Solar twins]] [[Category:Henry Draper Catalogue objects|101364]] [[Category:Hipparcos objects|056948]] [[Category:Durchmusterung objects|BD+69 0620]] [[Category:Population I stars]]