# 42 Draconis

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Star in the constellation Draco

42 Draconis / Fafnir Location of 42 Draconis (circled in red) Observation data Epoch J2000 Equinox J2000 Constellation Draco[1] Right ascension 18h 25m 59.13696s[2] Declination +65° 33′ 48.5313″[2] Apparent magnitude (V) 4.82[3] Characteristics Spectral type K1.5 III[3] B−V color index 1.18[1] Astrometry Radial velocity (Rv) 31.75±0.12[2] km/s Proper motion (μ) RA: +105.816 mas/yr[2] Dec.: −26.846 mas/yr[2] Parallax (π) 11.056±0.0841 mas[2] Distance 295 ± 2 ly (90.4 ± 0.7 pc) Absolute magnitude (MV) −0.10[1] Details[4] Mass 1.07±0.01 M☉ Radius 19.78±0.17 R☉ Luminosity 129.26+1.77 −1.05 L☉ Surface gravity (log g) 1.9±0.02 cgs Temperature 4,449+11 −17 K Metallicity [Fe/H] −0.43±0.01 dex Rotation 554±142 d (~479 or ~690 d) Rotational velocity (v sin i) 1.76±0.45 km/s Age 9.49±1.76[5] Gyr 13.19±1.92[3] Gyr Other designations Fafnir, BD+65°1271, GC 25212, HD 170693, HIP 90344, HR 6945, SAO 17888, PPM 20916, GCRV 10941 Database references SIMBAD data Exoplanet Archive data

**42 Draconis** (abbreviated **42 Dra**), formally named **Fafnir** ([/ˈfɑːvnər/](https://en.wikipedia.org/wiki/Help:IPA/English) or [/ˈfɑːfnɪər/](https://en.wikipedia.org/wiki/Help:IPA/English)),[6][7] is a 5th [magnitude](/source/Apparent_magnitude) [K-type](/source/K-type_star) [giant](/source/Giant_star) [star](/source/Star) located approximately 295 [light-years](/source/Light-year) away in the [constellation](/source/Constellation) of [Draco](/source/Draco_(constellation)). An [exoplanet](/source/Exoplanet) (designated 42 Draconis b, later named Orbitar) was once thought to be orbiting the star, but its existence has since been refuted.[4]

Of [spectral type](/source/Spectral_classification) K1.5III, the star has a mass similar to the [Sun](/source/Sun) but with a radius 22 times greater. It is a metal-poor star with metallicity as low as 35% that of the Sun and its age is 9.49 billion years. It is the southern [pole star](/source/Pole_star) of [Venus](/source/Venus).[8]

A 2019 study using [Gaia DR2](/source/Gaia_DR2) data found a companion star to 42 Draconis, about half the Sun's mass, at a separation of 24 [arcseconds](/source/Arcsecond), corresponding to 2220 [AU](/source/Astronomical_unit).[9]

## Nomenclature

42 Draconis in optical light

42 Draconis is the star's [Flamsteed designation](/source/Flamsteed_designation). Following its discovery the planet was designated 42 Draconis b. In July 2014 the [International Astronomical Union](/source/International_Astronomical_Union) launched [NameExoWorlds](/source/NameExoWorlds), a process for giving proper names to certain exoplanets and their host stars.[10] The process involved public nomination and voting for the new names.[11] In December 2015, the IAU announced the winning names were Fafnir for this star and Orbitar for its planet.[12]

The winning names were submitted by the Brevard Astronomical Society of [Brevard County, Florida](/source/Brevard_County%2C_Florida), [United States](/source/United_States).[13] [Fafnir](/source/Fafnir) was a [Norse mythological](/source/Norse_mythology) [dwarf](/source/Dwarf_(folklore)) who turned into a [Germanic dragon](/source/Germanic_dragon). It is also the name of a fictional planet in [Larry Niven](/source/Larry_Niven)'s [Known Space](/source/Known_Space) universe of similar description, ('Draco' is [Latin](/source/Latin) for 'dragon'); Orbitar is a contrived word paying homage to the space launch and orbital operations of [NASA](/source/NASA).[14]

In 2016, the IAU organized a [Working Group on Star Names](/source/IAU_Working_Group_on_Star_Names) (WGSN)[15] to catalog and standardize proper names for stars. In its first bulletin of July 2016,[16] the WGSN explicitly recognized the names of exoplanets and their host stars approved by the Executive Committee Working Group Public Naming of Planets and Planetary Satellites, including the names of stars adopted during the 2015 NameExoWorlds campaign. This star is now so entered in the IAU Catalog of Star Names.[7]

## Disproven planet

"Orbitar" redirects here. For the video game weapon, see [Kid Icarus: Uprising](/source/Kid_Icarus%3A_Uprising).

The discovery of 42 Draconis b (later named Orbitar) by the [radial velocity method](/source/Radial_velocity_method) was announced in 2009. It was thought to be a [super-Jupiter](/source/Super-Jupiter), with a [minimum mass](/source/Minimum_mass) 4 times that of Jupiter, an orbital period of 479 days, and an [eccentricity](/source/Orbital_eccentricity) of 0.38.[5] However, the existence of this planet was questioned in a 2021 study by the same authors, which found that more recent radial velocity measurements were inconsistent with the proposed planetary orbit.[17] With further observations, by 2025 the planet hypothesis could be conclusively ruled out.[4] The star appears to have intrinsic radial velocity variations that mimic a planetary companion, as observed in other giant stars such as [Gamma Draconis](/source/Gamma_Draconis) and [Aldebaran](/source/Aldebaran).[4]

In a 2024 study, 42 Draconis b was listed as one of several doubtful planets around giant stars, along with other named planets around [14 Andromedae](/source/14_Andromedae) and [41 Lyncis](/source/41_Lyncis).[18] With the 2025 refutation, it is now the second named exoplanet to be conclusively disproven, after [Fomalhaut b](/source/Fomalhaut_b) (Dagon) in 2020.[19]

## See also

- [HD 139357](/source/HD_139357)

- [Iota Draconis](/source/Iota_Draconis)

- [Lists of exoplanets](/source/Lists_of_exoplanets)

## 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=90344&-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) 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%3D2256800156349110528%26-go+%25%23Sesame%23%25%26) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-Ligi2016_3-0) [***b***](#cite_ref-Ligi2016_3-1) [***c***](#cite_ref-Ligi2016_3-2) Ligi, R.; et al. (February 2016), "Radii, masses, and ages of 18 bright stars using interferometry and new estimations of exoplanetary parameters", *Astronomy & Astrophysics*, **586**: 23, [arXiv](/source/ArXiv_(identifier)):[1511.03197](https://arxiv.org/abs/1511.03197), [Bibcode](/source/Bibcode_(identifier)):[2016A&A...586A..94L](https://ui.adsabs.harvard.edu/abs/2016A&A...586A..94L), [doi](/source/Doi_(identifier)):[10.1051/0004-6361/201527054](https://doi.org/10.1051%2F0004-6361%2F201527054), [S2CID](/source/S2CID_(identifier)) [15941645](https://api.semanticscholar.org/CorpusID:15941645), A94.

1. ^ [***a***](#cite_ref-Hatzes2025_4-0) [***b***](#cite_ref-Hatzes2025_4-1) [***c***](#cite_ref-Hatzes2025_4-2) [***d***](#cite_ref-Hatzes2025_4-3) Hatzes, Artie P.; Perdelwitz, Volker; et al. (May 2025). "No Planet around the K Giant Star 42 Draconis". *[Astronomy & Astrophysics](/source/Astronomy_%26_Astrophysics)*. **699**: A260. [arXiv](/source/ArXiv_(identifier)):[2505.05260](https://arxiv.org/abs/2505.05260). [Bibcode](/source/Bibcode_(identifier)):[2025A&A...699A.260H](https://ui.adsabs.harvard.edu/abs/2025A&A...699A.260H). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202554197](https://doi.org/10.1051%2F0004-6361%2F202554197).

1. ^ [***a***](#cite_ref-Döllinger2009_5-0) [***b***](#cite_ref-Döllinger2009_5-1) Döllinger, M. P.; et al. (2009). ["Planetary companion candidates around the K giant stars 42 Draconis and HD 139 357"](http://www.aanda.org/articles/aa/full_html/2009/21/aa10837-08/aa10837-08.html). *Astronomy and Astrophysics*. **499** (3): 935–942. [arXiv](/source/ArXiv_(identifier)):[0903.3593](https://arxiv.org/abs/0903.3593). [Bibcode](/source/Bibcode_(identifier)):[2009A&A...499..935D](https://ui.adsabs.harvard.edu/abs/2009A&A...499..935D). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/200810837](https://doi.org/10.1051%2F0004-6361%2F200810837). [S2CID](/source/S2CID_(identifier)) [15677079](https://api.semanticscholar.org/CorpusID:15677079).

1. **[^](#cite_ref-6)** ["Fafnir"](https://www.merriam-webster.com/dictionary/Fafnir). *[Merriam-Webster.com Dictionary](/source/Merriam-Webster)*. Merriam-Webster. [OCLC](/source/OCLC_(identifier)) [1032680871](https://search.worldcat.org/oclc/1032680871).

1. ^ [***a***](#cite_ref-IAU-CSN_7-0) [***b***](#cite_ref-IAU-CSN_7-1) ["IAU Catalog of Star Names"](http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt). Retrieved 28 July 2016.

1. **[^](#cite_ref-8)** [""Is Polaris the north star for all the other planets just like it is for Earth?" | Planetarium | University of Southern Maine"](https://web.archive.org/web/20221103123242/https://usm.maine.edu/planet/polaris-north-star-all-other-planets-just-it-earth). *usm.maine.edu*. Archived from [the original](https://usm.maine.edu/planet/polaris-north-star-all-other-planets-just-it-earth) on 2022-11-03. Retrieved 2022-07-12.

1. **[^](#cite_ref-Mugrauer2019_9-0)** Mugrauer, M. (December 2019). ["Search for stellar companions of exoplanet host stars by exploring the second ESA-Gaia data release"](https://doi.org/10.1093%2Fmnras%2Fstz2673). *[Monthly Notices of the Royal Astronomical Society](/source/Monthly_Notices_of_the_Royal_Astronomical_Society)*. **490** (4): 5088–5102. [Bibcode](/source/Bibcode_(identifier)):[2019MNRAS.490.5088M](https://ui.adsabs.harvard.edu/abs/2019MNRAS.490.5088M). [doi](/source/Doi_(identifier)):[10.1093/mnras/stz2673](https://doi.org/10.1093%2Fmnras%2Fstz2673).

1. **[^](#cite_ref-10)** [NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars](http://www.iau.org/news/pressreleases/detail/iau1404/). IAU.org. 9 July 2014

1. **[^](#cite_ref-11)** ["NameExoWorlds The Process"](https://web.archive.org/web/20150815025117/http://www.nameexoworlds.iau.org/process). Archived from [the original](http://nameexoworlds.iau.org/process) on 2015-08-15. Retrieved 2015-09-05.

1. **[^](#cite_ref-12)** [Final Results of NameExoWorlds Public Vote Released](http://www.iau.org/news/pressreleases/detail/iau1514/), International Astronomical Union, 15 December 2015.

1. **[^](#cite_ref-13)** [Website](http://www.brevardastro.org/)

1. **[^](#cite_ref-14)** ["NameExoWorlds The Approved Names"](https://web.archive.org/web/20180201043609/http://nameexoworlds.iau.org/names). Archived from [the original](http://nameexoworlds.iau.org/names) on 2018-02-01. Retrieved 2015-12-18.

1. **[^](#cite_ref-WGSN_15-0)** ["IAU Working Group on Star Names (WGSN)"](https://www.iau.org/science/scientific_bodies/working_groups/280/). Retrieved 22 May 2016.

1. **[^](#cite_ref-WGSN1_16-0)** ["Bulletin of the IAU Working Group on Star Names, No. 1"](http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf) (PDF). Retrieved 28 July 2016.

1. **[^](#cite_ref-DöllingerHartmann2021_17-0)** Döllinger, M. P.; Hartmann, M. (September 2021). ["A Sanity Check for Planets around Evolved Stars"](https://doi.org/10.3847%2F1538-4365%2Fac081a). *[The Astrophysical Journal Supplement Series](/source/The_Astrophysical_Journal_Supplement_Series)*. **256** (1): 10. [Bibcode](/source/Bibcode_(identifier)):[2021ApJS..256...10D](https://ui.adsabs.harvard.edu/abs/2021ApJS..256...10D). [doi](/source/Doi_(identifier)):[10.3847/1538-4365/ac081a](https://doi.org/10.3847%2F1538-4365%2Fac081a). [S2CID](/source/S2CID_(identifier)) [237369556](https://api.semanticscholar.org/CorpusID:237369556).

1. **[^](#cite_ref-Spaeth2024_18-0)** Spaeth, Dane; Reffert, Sabine; et al. (September 2024). "Non-radial oscillations mimicking a brown dwarf orbiting the cluster giant NGC 4349 No. 127". *[Astronomy & Astrophysics](/source/Astronomy_%26_Astrophysics)*. **689**: A91. [arXiv](/source/ArXiv_(identifier)):[2407.21583](https://arxiv.org/abs/2407.21583). [Bibcode](/source/Bibcode_(identifier)):[2024A&A...689A..91S](https://ui.adsabs.harvard.edu/abs/2024A&A...689A..91S). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202450163](https://doi.org/10.1051%2F0004-6361%2F202450163).

1. **[^](#cite_ref-Gaspar2020_19-0)** Gáspár, András; Rieke, George H. (April 20, 2020). ["New HST data and modeling reveal a massive planetesimal collision around Fomalhaut"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7211925). *[PNAS](/source/PNAS)*. **117** (18): 9712–9722. [arXiv](/source/ArXiv_(identifier)):[2004.08736](https://arxiv.org/abs/2004.08736). [Bibcode](/source/Bibcode_(identifier)):[2020PNAS..117.9712G](https://ui.adsabs.harvard.edu/abs/2020PNAS..117.9712G). [doi](/source/Doi_(identifier)):[10.1073/pnas.1912506117](https://doi.org/10.1073%2Fpnas.1912506117). [PMC](/source/PMC_(identifier)) [7211925](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7211925). [PMID](/source/PMID_(identifier)) [32312810](https://pubmed.ncbi.nlm.nih.gov/32312810).

## External links

- Jean Schneider (2011). ["Notes for star 42 Dra"](https://web.archive.org/web/20090819031259/http://exoplanet.eu/star.php?st=42+Dra). *[Extrasolar Planets Encyclopaedia](/source/Extrasolar_Planets_Encyclopaedia)*. Archived from [the original](http://exoplanet.eu/star.php?st=42+Dra) on August 19, 2009. Retrieved 3 October 2011.

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 [42 Draconis](https://en.wikipedia.org/wiki/42_Draconis) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/42_Draconis?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.