# HIP 56948

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Star in the constellation Draco

HIP 56948 Observation data Epoch J2000 Equinox J2000 Constellation Draco[1] Right ascension 11h 40m 28.48394s[2] Declination +69° 00′ 30.5978″[2] Apparent magnitude (V) 8.67[1] Characteristics Evolutionary stage main sequence[2] Spectral type G5V[3] B−V color index 0.647±0.014[4] Astrometry Radial velocity (Rv) +5.4[5] km/s Proper motion (μ) RA: −126.843[2] mas/yr Dec.: −2.470[2] mas/yr Parallax (π) 16.7935±0.0139 mas[2] Distance 194.2 ± 0.2 ly (59.55 ± 0.05 pc) Absolute magnitude (MV) +4.65[1] Details Mass 0.98[6] M☉ Radius 0.99[6] R☉ Luminosity 1.01[6] L☉ Surface gravity (log g) 4.409[7] cgs Temperature 5,774[6] K Metallicity [Fe/H] 0.02[7] dex Rotational velocity (v sin i) 1.0[8] km/s Age ~7.1[9] Gyr Other designations HD 101364, BD+69 620, SAO 15590. Database references SIMBAD data

**HIP 56948** (also known as **HD 101364**) is a [solar twin](/source/Solar_analog) star of type [G5V](/source/Stellar_classification).[3] 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](/source/Main_sequence).[9][10]

Cross-section of a solar-type star ([NASA](/source/NASA))

It is 208 [light years](/source/Light_years) away in the constellation of [Draco](/source/Draco_(constellation)),[11] lying about halfway between [Polaris](/source/Polaris) and [Dubhe](/source/Dubhe) on the celestial sphere.[12] Astronomers have looked for planets in the system, so far without finding any. These observations suggest that the star does not have any [hot Jupiters](/source/Hot_Jupiter).[13]

[Jorge Meléndez](https://en.wikipedia.org/w/index.php?title=Jorge_Mel%C3%A9ndez_(astronomer)&action=edit&redlink=1) of the [Australian National University](/source/Australian_National_University) and [Iván Ramírez](https://en.wikipedia.org/w/index.php?title=Iv%C3%A1n_Ram%C3%ADrez_(astronomer)&action=edit&redlink=1) of the [University of Texas](/source/University_of_Texas) analysed the star in 2007 using the 2.7 metre [Harlan J. Smith telescope](/source/Harlan_J._Smith_telescope) at [McDonald Observatory](/source/McDonald_Observatory).[14]

Most other solar analogs such as [18 Scorpii](/source/18_Scorpii) are unlike the Sun in that they have several times the [lithium](/source/Lithium) abundance. HIP 56948 is among the best candidates for a [solar twin](/source/Solar_twin) because of the known possible contenders, its lithium abundance most resembles that of the Sun.[7][15] A 2009 high-dispersion spectroscopic study from the Astronomical Society of Japan confirms this.[7]

In the abstract to their paper, the star's discoverers say:[10]

For more than a decade, [18 Sco](/source/18_Scorpii) (HD 146233) has been considered the star that most closely resembles the [Sun](/source/Sun), even though significant differences such as its [Li](/source/Lithium) content, which is about 3 times solar, exist. Using high-resolution, high-S/N spectra obtained at [McDonald Observatory](/source/McDonald_Observatory), we show that the stars HIP 56948 and [HIP 73815](/source/HD_133600) 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](/source/Solar_twin) known to date. HIP 56948 is also similar to the Sun in its lack of [hot Jupiters](/source/Hot_Jupiter). Considering the age of this star (~1 ± 1 Gyr older than the Sun)[Notes 1] and its location and orbit around the [Galaxy](/source/Milky_Way_Galaxy), if [terrestrial planets](/source/Terrestrial_planet) exist around it, they may have had enough time to develop complex life, making it a prime target for [SETI](/source/SETI).

— Jorge Meléndez and Iván Ramírez, 8 October 2007

## See also

- [Planetary habitability](/source/Planetary_habitability)

- [Rare Earth hypothesis](/source/Rare_Earth_hypothesis)

## Notes

1. **[^](#cite_ref-16)** The star's age estimate has been revised several times in different studies, most recently (as of February 2020) to 7.1 Gyr.[9]

## References

1. ^ [***a***](#cite_ref-xhip_1-0) [***b***](#cite_ref-xhip_1-1) [***c***](#cite_ref-xhip_1-2) Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". *[Astronomy Letters](/source/Astronomy_Letters)*. **38** (5): 331. [arXiv](/source/ArXiv_(identifier)):[1108.4971](https://arxiv.org/abs/1108.4971). [Bibcode](/source/Bibcode_(identifier)):[2012AstL...38..331A](https://ui.adsabs.harvard.edu/abs/2012AstL...38..331A). [doi](/source/Doi_(identifier)):[10.1134/S1063773712050015](https://doi.org/10.1134%2FS1063773712050015). [XHIP record for this object](https://vizier.cds.unistra.fr/viz-bin/VizieR-4?-ref=VIZ681510a8389ecb&-out.src=V%2F137D%2FXHIP&-nav=cat%3AV%2F137D%26tab%3A{V%2F137D%2FXHIP}%26key%3Asource%3DV%2F137D%2FXHIP%26HTTPPRM%3A&-source=V%2F137D%2FXHIP&-out=HIP&HIP=56948&-out=Comp&-out=Gr&-out=RAJ2000&-out=DEJ2000&-out=Dist&-out=X&-out=Y&-out=Z&-out=SpType&-out=Simbad&-out=Hpmag&-out=Lum&-out=Cst) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-dr3_2-0) [***b***](#cite_ref-dr3_2-1) [***c***](#cite_ref-dr3_2-2) [***d***](#cite_ref-dr3_2-3) [***e***](#cite_ref-dr3_2-4) [***f***](#cite_ref-dr3_2-5) Vallenari, A.; et al. (Gaia collaboration) (2023). ["*Gaia* Data Release 3. Summary of the content and survey properties"](https://doi.org/10.1051%2F0004-6361%2F202243940). *Astronomy and Astrophysics*. **674**: A1. [arXiv](/source/ArXiv_(identifier)):[2208.00211](https://arxiv.org/abs/2208.00211). [Bibcode](/source/Bibcode_(identifier)):[2023A&A...674A...1G](https://ui.adsabs.harvard.edu/abs/2023A&A...674A...1G). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202243940](https://doi.org/10.1051%2F0004-6361%2F202243940). [S2CID](/source/S2CID_(identifier)) [244398875](https://api.semanticscholar.org/CorpusID:244398875). [Gaia DR3 record for this source](https://vizier.cds.unistra.fr/viz-bin/VizieR-4?-source=+I%2F355&-from=nav&-nav=cat%3AI%2F355%26tab%3A%7BI%2F355%2Fgaiadr3%7D%26key%3Asource%3D1355%2Fgaiadr3%26HTTPPRM%3A%26-out.add%3D.%26Source%3D%3D%3D1061266013453102080%26-go+%25%23Sesame%23%25%26) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-vazquez_et_al_2010_3-0) [***b***](#cite_ref-vazquez_et_al_2010_3-1) Vázquez, M.; Pallé, E.; Rodríguez, P. Montañés (2010). "Is Our Environment Special?". [*The Earth as a Distant Planet: A Rosetta Stone for the Search of Earth-Like Worlds*](https://archive.org/details/earthasdistantpl00vazq). Astronomy and Astrophysics Library. Springer New York. pp. [391](https://archive.org/details/earthasdistantpl00vazq/page/n405)–418. [doi](/source/Doi_(identifier)):[10.1007/978-1-4419-1684-6](https://doi.org/10.1007%2F978-1-4419-1684-6). [ISBN](/source/ISBN_(identifier)) [978-1-4419-1683-9](https://en.wikipedia.org/wiki/Special:BookSources/978-1-4419-1683-9). See table 9.1.

1. **[^](#cite_ref-aaa474_2_653_4-0)** van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". *Astronomy and Astrophysics*. **474** (2): 653–664. [arXiv](/source/ArXiv_(identifier)):[0708.1752](https://arxiv.org/abs/0708.1752). [Bibcode](/source/Bibcode_(identifier)):[2007A&A...474..653V](https://ui.adsabs.harvard.edu/abs/2007A&A...474..653V). [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20078357](https://doi.org/10.1051%2F0004-6361%3A20078357). [S2CID](/source/S2CID_(identifier)) [18759600](https://api.semanticscholar.org/CorpusID:18759600).[Vizier catalog entry](http://vizier.cfa.harvard.edu/viz-bin/VizieR-5?-ref=VIZ56aafaa66eee&-out.add=.&-source=I/311/hip2&recno=56763)

1. **[^](#cite_ref-aaa418_989_5-0)** Nordström, B.; et al. (May 2004). "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14 000 F and G dwarfs". *Astronomy and Astrophysics*. **418** (3): 989–1019. [arXiv](/source/ArXiv_(identifier)):[astro-ph/0405198](https://arxiv.org/abs/astro-ph/0405198). [Bibcode](/source/Bibcode_(identifier)):[2004A&A...418..989N](https://ui.adsabs.harvard.edu/abs/2004A&A...418..989N). [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20035959](https://doi.org/10.1051%2F0004-6361%3A20035959). [S2CID](/source/S2CID_(identifier)) [11027621](https://api.semanticscholar.org/CorpusID:11027621).

1. ^ [***a***](#cite_ref-hu2023_6-0) [***b***](#cite_ref-hu2023_6-1) [***c***](#cite_ref-hu2023_6-2) [***d***](#cite_ref-hu2023_6-3) Hardegree-Ullman, Kevin K.; Apai, Dániel; Bergsten, Galen J.; Pascucci, Ilaria; López-Morales, Mercedes (2023). ["Bioverse: A Comprehensive Assessment of the Capabilities of Extremely Large Telescopes to Probe Earth-like O2 Levels in Nearby Transiting Habitable-zone Exoplanets"](https://doi.org/10.3847%2F1538-3881%2Facd1ec). *The Astronomical Journal*. **165** (6): 267. [arXiv](/source/ArXiv_(identifier)):[2304.12490](https://arxiv.org/abs/2304.12490). [Bibcode](/source/Bibcode_(identifier)):[2023AJ....165..267H](https://ui.adsabs.harvard.edu/abs/2023AJ....165..267H). [doi](/source/Doi_(identifier)):[10.3847/1538-3881/acd1ec](https://doi.org/10.3847%2F1538-3881%2Facd1ec).

1. ^ [***a***](#cite_ref-pasj61_3_471_7-0) [***b***](#cite_ref-pasj61_3_471_7-1) [***c***](#cite_ref-pasj61_3_471_7-2) [***d***](#cite_ref-pasj61_3_471_7-3) Takeda, Yoichi; Tajitsu, Akito (June 2009). "High-Dispersion Spectroscopic Study of Solar Twins: HIP 56948, HIP 79672, and HIP 100963". *Publications of the Astronomical Society of Japan*. **61** (3): 471–480. [arXiv](/source/ArXiv_(identifier)):[0901.2509](https://arxiv.org/abs/0901.2509). [Bibcode](/source/Bibcode_(identifier)):[2009PASJ...61..471T](https://ui.adsabs.harvard.edu/abs/2009PASJ...61..471T). [doi](/source/Doi_(identifier)):[10.1093/pasj/61.3.471](https://doi.org/10.1093%2Fpasj%2F61.3.471).

1. **[^](#cite_ref-marsden2014_8-0)** Marsden, S. C.; Petit, P.; Jeffers, S. V.; Morin, J.; Fares, R.; Reiners, A.; Do Nascimento, J. -D.; Aurière, M.; Bouvier, J.; Carter, B. D.; Catala, C.; Dintrans, B.; Donati, J. -F.; Gastine, T.; Jardine, M.; Konstantinova-Antova, R.; Lanoux, J.; Lignières, F.; Morgenthaler, A.; Ramìrez-Vèlez, J. C.; Théado, S.; Van Grootel, V.; BCool Collaboration (2014). ["A BCool magnetic snapshot survey of solar-type stars"](https://doi.org/10.1093%2Fmnras%2Fstu1663). *Monthly Notices of the Royal Astronomical Society*. **444** (4): 3517. [arXiv](/source/ArXiv_(identifier)):[1311.3374](https://arxiv.org/abs/1311.3374). [Bibcode](/source/Bibcode_(identifier)):[2014MNRAS.444.3517M](https://ui.adsabs.harvard.edu/abs/2014MNRAS.444.3517M). [doi](/source/Doi_(identifier)):[10.1093/mnras/stu1663](https://doi.org/10.1093%2Fmnras%2Fstu1663).

1. ^ [***a***](#cite_ref-aaa2018_9-0) [***b***](#cite_ref-aaa2018_9-1) [***c***](#cite_ref-aaa2018_9-2) M. Mittag; K.-P. Schröder; A. Hempelmann; J.N. González-Pérez & J.H.M.M. Schmitt (3 September 2018). "Chromospheric activity and evolutionary age of the Sun and foursolar twins". *[Astronomy & Astrophysics](/source/Astronomy_%26_Astrophysics)*. **591**: A89. [arXiv](/source/ArXiv_(identifier)):[1607.01279v1](https://arxiv.org/abs/1607.01279v1). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/201527542](https://doi.org/10.1051%2F0004-6361%2F201527542). [S2CID](/source/S2CID_(identifier)) [54765864](https://api.semanticscholar.org/CorpusID:54765864).

1. ^ [***a***](#cite_ref-hip_10-0) [***b***](#cite_ref-hip_10-1) Meléndez, Jorge; Iván Ramírez (2007). "HIP 56948: A Solar Twin with a Low Lithium Abundance (abstract)". *[Astrophysical Journal Letters](/source/Astrophysical_Journal_Letters)*. **669** (2): L89. [arXiv](/source/ArXiv_(identifier)):[0709.4290](https://arxiv.org/abs/0709.4290). [Bibcode](/source/Bibcode_(identifier)):[2007ApJ...669L..89M](https://ui.adsabs.harvard.edu/abs/2007ApJ...669L..89M). [doi](/source/Doi_(identifier)):[10.1086/523942](https://doi.org/10.1086%2F523942). [S2CID](/source/S2CID_(identifier)) [15952981](https://api.semanticscholar.org/CorpusID:15952981).

1. **[^](#cite_ref-11)** Shiga, David (2007-10-03). ["Sun's 'twin' an ideal hunting ground for alien life"](https://www.newscientist.com/article/dn12725). *[New Scientist](/source/New_Scientist)*. Retrieved 2009-05-28.

1. **[^](#cite_ref-12)** [The Telegraph](https://web.archive.org/web/20100909202924/http://www.telegraph.co.uk/science/space/7808214/Night-Sky-in-June-2010.html), retrieved 5 November 2010.

1. **[^](#cite_ref-13)** [New Scientist](https://www.newscientist.com/article/dn12725), retrieved 5 October 2009.

1. **[^](#cite_ref-14)** ["Light of the Dragon: Astronomers Discover Sun's Twin at McDonald Observatory"](http://www.astrobio.net/news/modules.php?op=modload&name=News&file=article&sid=2522). *[Astrobiology Magazine](/source/Astrobiology_Magazine)*. 2007-11-13. Retrieved 2009-05-28.

1. **[^](#cite_ref-15)** Mosher, Dave (2007-11-09). ["Astronomers find the sun's long-lost twin: Happy reunion unlikely, as the star is about 200 light-years away"](http://www.nbcnews.com/id/21714413). [NBC News](/source/NBC_News). Retrieved 2009-05-28.[*[dead link](https://en.wikipedia.org/wiki/Wikipedia:Link_rot)*]

v t e Constellation of Draco List of stars in Draco Draco in Chinese astronomy Stars Bayer α (Thuban) β (Rastaban) γ (Eltanin) δ (Altais) ε (Tyl) ζ (Aldhibah) η (Athebyne) θ ι (Edasich) κ λ (Giausar) μ (Alrakis) ν (Kuma) ξ (Grumium) ο π ρ σ (Alsafi) τ υ φ χ ψ1 (Dziban) ψ2 ω Flamsteed 4 6 7 (Tianyi) 8 (Taiyi) 10 (i) 15 (A) 18 (g) 19 (h) 26 36 39 (b) 42 (Fafnir) 45 (d) 50 59 64 (e) 68 Variable TW YY AG BY CL CM CX DO EK HP V581 HR 3751 4126 4934 5811 6237 6518 6618 (Alruba) 6817 7137 7783 HD 109246 (Funi) 101364 128717 147379 156279 158259 176693 191939 Other 2MASS 1237+6526 2MASS J17554042+6551277 G 240-72 GD 356 Gliese 420 Gliese 625 Gliese 687 GRW +70 8247 Kepler-4 Kepler-10 Kepler-12 Kepler-90 Kepler-296 KOI-256 LP 71-82 Qatar-1 SDSS J1240+6710 Struve 2398 TOI-1136 WD 1856+534 WISE 1647+5632 WISE 1841+7000 Exoplanets HD 139357 b HD 167042 b ι Dra b (Hypatia) Kepler-4b Kepler-10b c Kepler-12b Kepler-90e f g h i Kepler-296b c d e f TOI-1452 b TrES-2b Star clusters LAMOST 1 Nebulae Cat's Eye Nebula NGC 6742 Galaxies NGC 3147 3197 3735 4121 4125 4221 4236 4319 4331 4332 4363 4441 4513 4545 4589 5678 5777 5866 5866B 5879 5905 5907 5949 5963 5965 5982 5985 6090 6248 6285 6286 6338 6340 6365 6373 6394 6412 6503 6505 6566 6621 6622 6670 6676 6786 6789 Other 1ES 1927+654 1ES 1959+650 3C 249.1 3C 305 3C 319 3C 343 3C 343.1 3C 351 3C 356 3C 371 3C 380 3C 390.3 3C 401 4C +72.26 4C 73.08 8C 1241+735 Abell 2218 BCG Bean galaxy Beaver galaxy BZQ J1727+5510 Draco Dwarf Draco II GB 1508+5714 Goldfish galaxy H1821+643 HFLS3 IERS B1946+708 IRAS F17179+5444 IRAS 18580+6527 J120011.1+680924.8 KKR 25 Markarian 817 Markarian 876 Original TRG PGC 39058 Porphyrion QSO B1823+568 RGZ J172749.5+534647 S5 1803+784 S5 2007+777 SDSS J1715+6008 Tadpole Galaxy UGC 9391 UGC 9405 UGC 11241 UGC 11411 WISEA J145223.62+611707.5 WN B1851+5707 Galaxy clusters Abell 2218 CL1358+62 Draco Supercluster NGC 5866 Group Astronomical events SN 2003jb SN 2005B SN 2016aps Swift J1644+57 Category

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Adapted from the Wikipedia article [HIP 56948](https://en.wikipedia.org/wiki/HIP_56948) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/HIP_56948?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.