# Pherkad

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**Pherkad** /f3rkæd/,[1][2] also known **as Gamma Ursae Minoris** **or γ Ursae Minoris**, abbreviated **Gamma UMi**, **γ UMi**, is a [star](/source/Star) in the northern [constellation](/source/Constellation) of [Ursa Minor](/source/Ursa_Minor). Together with [Beta Ursae Minoris](/source/Beta_Ursae_Minoris) (Kochab), it forms the end of the dipper pan of the "Little Dipper", which is an [asterism](/source/Asterism_(astronomy)) forming the tail of the bear. Based upon [parallax](/source/Stellar_parallax) measurements obtained during the [Hipparcos](/source/Hipparcos) mission, it is approximately 487 light-years (149 parsecs) from the [Sun](/source/Sun).[3]

## Nomenclature

*γ Ursae Minoris* ([Latinised](/source/Latinisation_of_names) to *Gamma Ursae Minoris*) is the star's [Bayer designation](/source/Bayer_designation). The fainter [11 Ursae Minoris](/source/11_Ursae_Minoris) has been called *γ1 Ursae Minoris*, in which case *Gamma Ursae Minoris* would be designated *γ2*. However this usage is rarely seen.[4]

Gamma Ursae Minoris bore the traditional name *Pherkad*, which derived from the Arabic فرقد *farqad* "calf", short for *aḫfa al farkadayn* "the dim one of the two calves", that is Pherkad and Kochab (the full name [Ahfa al Farkadain](/source/Ahfa_al_Farkadain) is traditionally applied to [Zeta Ursae Minoris](/source/Zeta_Ursae_Minoris)).[citation needed] Gamma Ursae Minoris was mostly called *Pherkad Major* to distinguish it from *Pherkad Minor* (11 Ursae Minoris). In 2016, the [International Astronomical Union](/source/International_Astronomical_Union) organized a [Working Group on Star Names](/source/IAU_Working_Group_on_Star_Names) (WGSN)[5] to catalogue and standardize proper names for stars. The WGSN approved the name *Pherkad* for Gamma Ursae Minoris on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.[2]

In [Chinese](/source/Chinese_astronomy), 北極 (*Běi Jí*), meaning *[North Pole](/source/Purple_Forbidden_enclosure)*, refers to an asterism consisting of Gamma Ursae Minoris, [Beta Ursae Minoris](/source/Beta_Ursae_Minoris), [5 Ursae Minoris](/source/5_Ursae_Minoris), [4 Ursae Minoris](/source/4_Ursae_Minoris) and [Σ 1694](/source/%CE%A3_1694).[6] Consequently, the [Chinese name](/source/Chinese_star_name) for Gamma Ursae Minoris itself is 北極一 (*Běi Jí yī*, English: *the First Star of North Pole*), representing 太子 (*Tàizǐ*), meaning *Crown Prince*.[7]

## Properties

Gamma Ursae Minoris has [apparent magnitude](/source/Apparent_magnitude) +3.05[8] and can be readily observed with the naked eye even in a [city-lit night sky](/source/Bortle_Dark-Sky_Scale). It has an [absolute magnitude](/source/Absolute_magnitude) of –2.84.[9] Measurement of the star's [spectrum](/source/Stellar_spectrum) resulted in a [stellar classification](/source/Stellar_classification) of A2 III,[10] with the [luminosity class](/source/Luminosity_class) of 'III' indicating this is an expanding [giant star](/source/Giant_star) that left the main sequence after exhausting its core supply of [hydrogen](/source/Hydrogen). Based on stellar evolutionary theory, Pherkad might become a [Cepheid variable](/source/Cepheid_variable) before settling as a [red giant](/source/Red_giant) similar to its neighbor Kochab, before becoming a [white dwarf](/source/White_dwarf) of roughly 0.85 [solar masses](/source/Solar_mass).[11] The [effective temperature](/source/Effective_temperature) of the star's outer envelope is 8,280 K,[12] giving it the typical white hue of an [A-type](/source/Stellar_classification#Class_A) star.[13] It is rotating rapidly, with the [projected rotational velocity](/source/Stellar_rotation) of 180 km s−1[14] providing a lower limit on the [azimuthal](/source/Azimuth) velocity along the star's equator.

This is classified as a [shell star](/source/Shell_star) that has a circumstellar disk of gas around the star's equator, which may be causing it to vary in magnitude.[15] It is 1100 times more luminous [than the Sun](/source/Solar_luminosity), and possesses a radius 15 times that [of the Sun](/source/Solar_radius).[11]

## Pherkad in fiction

Pherkad (spelled as *Pherkard*) features in [Cthulhu Mythos](/source/Cthulhu_Mythos).

## References

1. Rumrill, H. B. (June 1936). "Star Name Pronunciation". *Publications of the Astronomical Society of the Pacific*. **48** (283): 139. [Bibcode:1936PASP...48..139R](https://ui.adsabs.harvard.edu/abs/1936PASP...48..139R). [doi:10.1086/124681](https://doi.org/10.1086/124681). [S2CID 120743052](https://api.semanticscholar.org/CorpusID:120743052)

1. ["Naming Stars"](https://web.archive.org/web/20250310063743/https://www.iau.org/public/themes/naming_stars/). IAU.org. Archived from [the original](https://www.iau.org/public/themes/naming_stars/) on 10 March 2025. Retrieved 4 March 2018.

1. van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", *Astronomy and Astrophysics*. **474** (2): 653–664, [arXiv:0708.1752](https://arxiv.org/abs/0708.1752). [Bibcode:2007A&A...474..653V](https://ui.adsabs.harvard.edu/abs/2007A%26A...474..653V). [doi:10.1051/0004-6361:20078357](https://doi.org/10.1051/0004-6361:20078357). [S2CID 18759600](https://api.semanticscholar.org/CorpusID:18759600)

1. Kostjuk, N. D. (2004). "VizieR Online Data Catalog: HD-DM-GC-HR-HIP-Bayer-Flamsteed Cross Index (Kostjuk, 2002)". *VizieR On-line Data Catalog: IV/27A. Originally Published in: Institute of Astronomy of Russian Academy of Sciences (2002)*. **4027**. [Bibcode:2004yCat.4027....0K](https://ui.adsabs.harvard.edu/abs/2004yCat.4027....0K)

1. ["IAU Working Group on Star Names (WGSN)"](https://web.archive.org/web/20190330194042/https://www.iau.org/science/scientific_bodies/working_groups/280/), [International Astronomical Union](/source/International_Astronomical_Union), archived from [the original](https://www.iau.org/science/scientific_bodies/working_groups/280/) on 30 March 2019, retrieved 22 May 2016

1. (in Chinese) *中國星座神話*, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.

1. (in Chinese) [香港太空館 - 研究資源 - 亮星中英對照表](http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/e_research_chinengstarzone_b.htm#PrupleForbiddenEnclosure) [Archived](https://web.archive.org/web/20100810114313/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/e_research_chinengstarzone_b.htm#PrupleForbiddenEnclosure) August 10, 2010 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.

1. Fernie, J. D. (May 1983), "New UBVRI photometry for 900 supergiants", *Astrophysical Journal Supplement Series*. **52**: 7–22, [Bibcode:1983ApJS...52....7F](https://ui.adsabs.harvard.edu/abs/1983ApJS...52....7F). [doi:10.1086/190856](https://doi.org/10.1086/190856)

1. Verdugo, E. et al. (November 2005). "Do A-type Supergiants have Magnetic Fields?". *The Nature and Evolution of Disks Around Hot Stars; Proceedings of a meeting held 7-9 July 2004 in Johnson City, Tennessee, USA*. *The Nature and Evolution of Disks Around Hot Stars*. **337**: 324. ASP Conference Series. [Bibcode:2005ASPC..337..324V](https://ui.adsabs.harvard.edu/abs/2005ASPC..337..324V)

1. Abt, Helmut A. & Morrell, Nidia I. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". *Astrophysical Journal Supplement Series*. **99**: 135. [Bibcode:1995ApJS...99..135A](https://ui.adsabs.harvard.edu/abs/1995ApJS...99..135A). [doi:10.1086/192182](https://doi.org/10.1086/192182)

1. Kaler, James B., ["Pherkad (Gamma Ursae Minoris)"](http://stars.astro.illinois.edu/sow/pherkad.html), *Stars*, [University of Illinois](/source/University_of_Illinois), retrieved 2007-10-05

1. Zorec, J. et al. (July 2009), "Fundamental parameters of B supergiants from the BCD system. I. Calibration of the (λ_1, D) parameters into Teff", *Astronomy and Astrophysics*. **501** (1): 297–320, [arXiv:0903.5134](https://arxiv.org/abs/0903.5134). [Bibcode:2009A&A...501..297Z](https://ui.adsabs.harvard.edu/abs/2009A%26A...501..297Z). [doi:10.1051/0004-6361/200811147](https://doi.org/10.1051/0004-6361/200811147). [S2CID 14969137](https://api.semanticscholar.org/CorpusID:14969137)

1. ["The Colour of Stars"](https://web.archive.org/web/20120318151427/http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html), *Australia Telescope, Outreach and Education*, [Commonwealth Scientific and Industrial Research Organisation](/source/Commonwealth_Scientific_and_Industrial_Research_Organisation), December 21, 2004, archived from [the original](http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html) on 2012-03-18, retrieved 2012-01-16

1. Royer, F. et al. (October 2002), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i", *Astronomy and Astrophysics*. **393** (3): 897–911, [arXiv:astro-ph/0205255](https://arxiv.org/abs/astro-ph/0205255). [Bibcode:2002A&A...393..897R](https://ui.adsabs.harvard.edu/abs/2002A%26A...393..897R). [doi:10.1051/0004-6361:20020943](https://doi.org/10.1051/0004-6361:20020943). [S2CID 14070763](https://api.semanticscholar.org/CorpusID:14070763)

1. Hauck, B. & Jaschek, C. (February 2000), "A-shell stars in the Geneva system", *Astronomy and Astrophysics*. **354**: 157–162, [Bibcode:2000A&A...354..157H](https://ui.adsabs.harvard.edu/abs/2000A%26A...354..157H)

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