Ursa Minor

{{anchor|History}}

File:Sidney Hall - Urania's Mirror - Draco and Ursa Minor.jpg,{{cite web|url=http://www.ianridpath.com/atlases/urania.html |title=Urania's Mirror c.1825 – Ian Ridpath's Antique Star Atlases |author=Ridpath, Ian |author-link=Ian Ridpath |publisher=Self-published |access-date=13 February 2012}} a set of constellation maps published in London c. 1825]]

In the Babylonian star catalogues, Ursa Minor was known as the "Wagon of Heaven" ({{lang|akk|^MULMAR.GÍD.DA.AN.NA}}, also associated with the goddess Damkina). It is listed in the MUL.APIN catalogue, compiled around 1000 BC, among the "Stars of Enlil"—that is, the northern sky.{{cite journal |author=Rogers, John H. |title= Origins of the Ancient Constellations: I. The Mesopotamian Traditions |journal=Journal of the British Astronomical Association |volume=108 |date=1998 |pages= 9–28 |bibcode= 1998JBAA..108....9R }}

According to Diogenes Laërtius, citing Callimachus, Thales of Miletus "measured the stars of the Wagon by which the Phoenicians sail". Diogenes identifies these as the constellation of Ursa Minor, which for its reported use by the Phoenicians for navigation at sea were also named Phoinikē.Hermann Hunger, David Edwin Pingree, Astral Sciences in Mesopotamia (1999), [https://books.google.com/books?id=7hnTZ8tdOS0C&pg=PA68 p. 68].{{cite journal|last=Albright|first=William F. |date=1972|title=Neglected Factors in the Greek Intellectual Revolution|journal=Proceedings of the American Philosophical Society |volume=116|issue=3|pages= 225–42|jstor=986117}}

The tradition of naming the northern constellations "bears" appears to be genuinely Greek, although Homer refers to just a single "bear".{{cite web| url=http://www.ianridpath.com/startales/ursaminor.html | title=Ursa Minor |last1=Ridpath|first1=Ian|publisher=Self-published |work=Star Tales | access-date= 7 March 2015}}

{{cite book|last=Blomberg|first=Peter E.|title=Archaeoastronomy in Archaeology and Ethnography: Papers from the Annual Meeting of SEAC (European Society for Astronomy in Culture), held in Kecskemét in Hungary in 2004|editor=Pásztor, Emília |publisher=Archaeopress|location=Oxford, UK|date=2007|pages=129–32|chapter=How Did the Constellation of the Bear Receive its Name?|isbn=978-1-4073-0081-8|chapter-url=http://minoanastronomy.mikrob.com/pdf/2007b%20Peter%20Kecs.pdf}}

The original "bear" is thus Ursa Major, and Ursa Minor was admitted as the second, or "Phoenician Bear" (Ursa Phoenicia, hence Φοινίκη, Phoenice)

only later, according to Strabo (I.1.6, C3) due to a suggestion by Thales, who suggested it as a navigation aid to the Greeks, who had been navigating by Ursa Major. In classical antiquity, the celestial pole was somewhat closer to Beta Ursae Minoris than to Alpha Ursae Minoris, and the entire constellation was taken to indicate the northern direction. Since the medieval period, it has become convenient to use Alpha Ursae Minoris (or "Polaris") as the North Star. (Even though, in the medieval period, Polaris was still several degrees away from the celestial pole.{{cite book|author=Kenneth R. Lang|title=Essential Astrophysics|url=https://books.google.com/books?id=PVJEAAAAQBAJ&pg=PA10|year= 2013|publisher=Springer Science & Business Media|isbn=978-3-642-35963-7|pages=10–15}}{{efn| The position of the north celestial pole moves in accordance with the Earth's axial precession such that in 12,000 years' time, Vega will be the Pole Star.}} ) Now, Polaris is within 1° of the north celestial pole and remains the current Pole star. Its Neo-Latin name of stella polaris was coined only in the early modern period.

The ancient name of the constellation is Cynosura (Greek Κυνοσούρα "dog's tail").

The origin of this name is unclear (Ursa Minor being a "dog's tail" would imply that another constellation nearby is "the dog", but no such constellation is known).{{cite book|title=Star Names: Their Lore and Meaning|url=https://archive.org/details/StarNamesAndTheirMeanings|author=Allen, Richard Hinckley|date=1899}} [https://penelope.uchicago.edu/Thayer/e/gazetteer/topics/astronomy/_texts/secondary/allsta/home.html 447f.]

"The origin of this word is uncertain, for the star group does not answer to its name unless the dog himself be attached; still some, recalling a variant legend of Kallisto and her Dog instead of Arcas, have thought that here lay the explanation. Others have drawn this title from that of the Attican promontory east of Marathon, because sailors, on their approach to it from the sea, saw these stars shining above it and beyond; but if there be any connection at all here, the reversed derivation is more probable; while Bournouf asserted that it is in no way associated with the Greek word for "dog."

Instead, the mythographic tradition of Catasterismi makes Cynosura the name of an Oread nymph described as a nurse of Zeus, honoured by the god with a place in the sky.[http://articles.adsabs.harvard.edu/full/1970ASPL...10..361C Condos, T., The Katasterismoi (Part 1), 1967]. Also mentioned by Servius On Virgilius' Georgics 1. 246, c. AD 400; a mention of doubtful authenticity is Hyginus, De astronomia 2.2.

There are various proposed explanations for the name Cynosura. One suggestion connects it to the myth of Callisto, with her son Arcas replaced by her dog being placed in the sky by Zeus.

Others have suggested that an archaic interpretation of Ursa Major was that of a cow, forming a group with Boötes as herdsman, and Ursa Minor as a dog.[https://archive.org/stream/researchesintoo01browgoog#page/n284/mode/2up/search/Syoronos 265f. Robert Brown, Researches into the origin of the primitive constellations of the Greeks, Phoenicians and Babylonians (1899)],

"M. Syoronos (Types Mon. des anciens p. 116) is of opinion that in the case of some Kretan coin-types, Ursa Maj. is represented as a Cow, hence Boôtês as 'the Herdsman', and Ursa Min. as a Dog ('Chienne' cf. Kynosoura, Kynoupês), a Zeus-suckler."

A supposed Latin tradition of naming Ursa Minor Catuli "whelps" or Canes Laconicae "Spartan dogs", recorded in Johann Heinrich Alsted (1649, [https://books.google.com/books?id=KGkp6GNTCOQC&pg=PA408 408]), is probably an early modern innovation. George William Cox explained it as a variant of Λυκόσουρα, understood as "wolf's tail" but by him etymologized as "trail, or train, of light" (i.e. λύκος "wolf" vs. λύκ- "light"). Allen points to the Old Irish name of the constellation, drag-blod "fire trail", for comparison.

Brown (1899) suggested a non-Greek origin of the name (a loan from an Assyrian An‑nas-sur‑ra "high-rising")."Very recently, however, Brown [Robert Brown, Researches into the origin of the primitive constellations of the Greeks, Phoenicians and Babylonians] has suggested that the word is not Hellenic in origin, but Euphratean; and, in confirmation of this, mentions a constellation title from that valley, transcribed by Sayce as An‑ta-sur‑ra, the Upper Sphere. Brown reads this An‑nas-sur‑ra, High in Rising, certainly very appropriate to Ursa Minor; and he compares it with Κ‑υν‑όσ‑ου‑ρα, or, the initial consonant being omitted, Unosoura." (Allen, Richard Hinckley. "Star Names: Their Lore and Meaning." New York, Dover Editions, 1963, p. 448.)

Brown points out that Aratus fittingly describes "Cynosura" as "high-running" ("at the close of night Cynosura's head runs very high", κεφαλὴ Κυνοσουρίδος ἀκρόθι νυκτὸς

ὕψι μάλα τροχάει v. 308f).

An alternative myth tells of two bears that saved Zeus from his murderous father Cronus by hiding him on Mount Ida. Later Zeus set them in the sky, but their tails grew long from their being swung up into the sky by the god.{{cite journal| author=Rogers, John H. |title= Origins of the Ancient Constellations: II. The Mediterranean traditions |journal=Journal of the British Astronomical Association |volume=108 |date=1998|pages= 79–89|bibcode = 1998JBAA..108...79R}}

Because Ursa Minor consists of seven stars, the Latin word for "north" (i.e., where Polaris points) is septentrio, from septem (seven) and triones (oxen), from seven oxen driving a plough, which the seven stars also resemble. This name has also been attached to the main stars of Ursa Major.{{cite book | last = Wagman | first = Morton | date = 2003 | title = Lost Stars: Lost, Missing and Troublesome Stars from the Catalogues of Johannes Bayer, Nicholas Louis de Lacaille, John Flamsteed, and Sundry Others | publisher = The McDonald & Woodward Publishing Company | location = Blacksburg, Virginia | isbn = 978-0-939923-78-6 |pages=312, 518}}

In Inuit astronomy, the three brightest stars — Polaris, Kochab, and Pherkad — were known as Nuutuittut ("never moving"), though the term is more frequently used in the singular to refer to Polaris alone. The Pole Star is too high in the sky at far northern latitudes to be of use in navigation.{{cite book | last = MacDonald | first = John | date = 1998 | title = The Arctic Sky: Inuit Astronomy, Star Lore, and Legend | url = https://archive.org/details/arcticskyinuitas0000macd | url-access = registration | publisher = Royal Ontario Museum/Nunavut Research Institute |location=Toronto, Ontario | isbn = 978-0-88854-427-8 |page=[https://archive.org/details/arcticskyinuitas0000macd/page/61 61]}} In Chinese astronomy, the main stars of Ursa Minor are divided between two asterisms:

勾陳 Gòuchén (Curved Array) (including α UMi, δ UMi, ε UMi, ζ UMi, η UMi, θ UMi, λ UMi) and

北極 Běijí (Northern Pole) (including β UMi and γ UMi).{{Cite web|title=Ursa Minor – Chinese associations|website=Star Tales|url=http://www.ianridpath.com/startales/ursaminor.html#chinese|access-date=2023-01-13}}

File:Book of the Fixed Stars Auv0043 ursa minor cropped.jpg, ca. 1009-1010. Unlike in western representations, the bear is drawn with its tail drooping down.]]

Ursa Minor is bordered by Camelopardalis to the west, Draco to the west, and Cepheus to the east. Covering 256 square degrees, it ranks 56th of the 88 constellations in size. Ursa Minor is colloquially known in the US as the Little Dipper because its seven brightest stars seem to form the shape of a dipper (ladle or scoop). The star at the end of the dipper handle is Polaris. Polaris can also be found by following a line through the two stars—Alpha and Beta Ursae Majoris, popularly called the Pointers—that form the end of the "bowl" of the Big Dipper, for 30 degrees (three upright fists at arms' length) across the night sky.{{cite book | author=O'Meara, Stephen James | title=The Messier Objects | series=Deep-sky Companions | publisher=Cambridge University Press |location=Cambridge, UK| year=1998 | isbn=978-0-521-55332-2 | url=https://archive.org/details/messierobjectsfi00omea | url-access=registration | page=[https://archive.org/details/messierobjectsfi00omea/page/10 10]}} The four stars constituting the bowl of the Little Dipper are of second, third, fourth, and fifth magnitudes, respectively, and provide an easy guide to determining what magnitude stars are visible, useful for city dwellers or testing one's eyesight.{{cite book | author=Olcott, William Tyler | author-link1=William Tyler Olcott | title=Star Lore of All Ages: A Collection of Myths, Legends, and Facts Concerning the Constellations of the Northern Hemisphere | publisher=Courier Corporation |location=New York, New York | date=2012 | orig-year=1911 | page=377 | url=https://books.google.com/books?id=ODJM51UvfzEC&pg=PA377| isbn=978-0-486-14080-3 }}

The three-letter abbreviation for the constellation, as adopted by the IAU (International Astronomical Union) in 1922, is "UMi".{{cite journal | last=Russell | first=Henry Norris |author-link=Henry Norris Russell | title=The New International Symbols for the Constellations | journal=Popular Astronomy | volume=30 | page=469 | bibcode=1922PA.....30..469R | date=1922}} The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of 22 segments (illustrated in infobox). In the equatorial coordinate system, the right ascension coordinates of these borders lie between {{RA|08|41.4}} and {{RA|22|54.0}}, while the declination coordinates range from the north celestial pole to 65.40° in the south.{{Cite journal | title=Ursa Minor, Constellation Boundary | journal=The Constellations | publisher=International Astronomical Union | url=https://www.iau.org/public/themes/constellations/#umi | access-date=12 May 2014}} Its position in the far northern celestial hemisphere means that the whole constellation is visible only to observers in the northern hemisphere.{{cite web| url=http://www.ianridpath.com/constellations2.html | title=Constellations: Lacerta–Vulpecula | work= Star Tales |author=Ridpath, Ian |publisher=Self-published | access-date= 21 June 2014}}{{efn|1=While parts of the constellation technically rise above the horizon to observers between the equator and 24°S, stars within a few degrees of the horizon are to all intents and purposes unobservable.}}

File:UrsaMinorCC.jpg

{{See also|List of stars in Ursa Minor}}

The German cartographer Johann Bayer used the Greek letters alpha to theta to label the most prominent stars in the constellation, while his countryman Johann Elert Bode subsequently added iota through phi. Only lambda and pi remain in use, likely because of their proximity to the north celestial pole. Within the constellation's borders, there are 39 stars brighter than or equal to apparent magnitude 6.5.{{efn|1=Objects of magnitude 6.5 are among the faintest visible to the unaided eye in suburban-rural transition night skies.{{cite web|url=http://www.skyandtelescope.com/resources/darksky/3304011.html?page=1&c=y|title=The Bortle Dark-Sky Scale|last=Bortle|first=John E.|date=February 2001|work=Sky & Telescope|access-date=29 November 2014|archive-date=31 March 2014|archive-url=https://web.archive.org/web/20140331202746/http://www.skyandtelescope.com/resources/darksky/3304011.html?page=1&c=y|url-status=dead}}}}

The traditional names of the main seven in Johann Bayer's ordering are:

1. Polaris
2. Kochab
3. Pherkad
4. Yildun
5. Epsilon Ursae Minoris has no traditional name.
6. Zeta Ursae Minoris has no traditional name.
7. Eta Ursae Minoris has no traditional name.

Marking the Little Bear's tail, Polaris, or Alpha Ursae Minoris, is the brightest star in the constellation, varying between apparent magnitudes 1.97 and 2.00 over a period of 3.97 days. Located around 432 light-years away from Earth,{{cite web |url = http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Alf+UMi&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title = Alpha Ursae Minoris – Classical Cepheid (Delta Cep Type) |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 19 August 2014}} it is a yellow-white supergiant that varies between spectral types F7Ib and F8Ib,{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=37413 |title=Alpha Ursae Minoris |author=Otero, Sebastian Alberto |date=4 December 2007 |work=The International Variable Star Index |publisher=American Association of Variable Star Observers|access-date=16 May 2014}} and has around 6 times the Sun's mass, 2,500 times its luminosity, and 45 times its radius. Polaris is the brightest Cepheid variable star visible from Earth. It is a triple star system, the supergiant primary star having two yellow-white main-sequence star companions that are 17 and 2,400 astronomical units (AU) distant and take 29.6 and 42,000 years respectively to complete one orbit.{{cite web| first1=James B. | last1=Kaler | title=Polaris | work=Stars | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/polaris.html | access-date=19 August 2014}}

Traditionally called Kochab, Beta Ursae Minoris, at apparent magnitude 2.08, is slightly less bright than Polaris. Located around 131 light-years away from Earth,{{cite journal | first=F. | last=van Leeuwen | title=Validation of the New Hipparcos Reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–64 | date=2007 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 | arxiv=0708.1752| s2cid=18759600 }}{{efn|1=Or more specifically 130.9±0.6 light-years by parallax measurement.}} it is an orange giant—an evolved star that has used up the hydrogen in its core and moved off the main sequence—of spectral type K4III.{{cite web |url = http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Bet+UMi&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title = Beta Ursae Minoris – Variable Star |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 18 May 2014}} Slightly variable over a period of 4.6 days, Kochab has had its mass estimated at 1.3 times that of the Sun via measurement of these oscillations.{{cite journal | last1 = Tarrant | first1 = N.J. | last2 = Chaplin| first2 = W.J.| last3 = Elsworth| first3 = Y.| last4 = Spreckley | first4 = S.A.| last5 = Stevens| first5 = I.R.| title = Oscillations in ß Ursae Minoris. Observations with SMEI | journal = Astronomy and Astrophysics | volume = 483 | issue = #3 | pages = L43–L46 |date=June 2008 | doi = 10.1051/0004-6361:200809738 | bibcode = 2008A&A...483L..43T | arxiv = 0804.3253 | s2cid = 53546805 }} Kochab is 450 times more luminous than the Sun and has 42 times its diameter, with a surface temperature of approximately 4,130 K.{{cite web| first1=James B. | last1=Kaler | title=Kochab | work=Stars | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/kochab.html | access-date=19 August 2014}} Estimated to be around 2.95 billion years old, ±1 billion years, Kochab was announced to have a planetary companion around 6.1 times as massive as Jupiter with an orbit of 522 days.{{cite journal |title=Planetary Companions in K giants β Cancri, μ Leonis, and β Ursae Minoris | author=Lee, B.-C. | author2=Han, I. | author3=Park, M.-G. | author4=Mkrtichian, D.E. | author5=Hatzes, A.P. | author6=Kim, K.-M.| journal = Astronomy and Astrophysics| volume = 566| id=A67 | pages=7 | date = 2014| doi =10.1051/0004-6361/201322608 | bibcode=2014A&A...566A..67L|arxiv = 1405.2127 | s2cid=118631934 }}

File:Ursa Major - Ursa Minor - Polaris.jpg

Traditionally known as Pherkad, Gamma Ursae Minoris has an apparent magnitude that varies between 3.04 and 3.09 roughly every 3.4 hours.{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=37414 |title=Gamma Ursae Minoris |author=Watson, Christopher |date=4 January 2010 |work=The International Variable Star Index |publisher=American Association of Variable Star Observers|access-date=18 May 2014}} It and Kochab have been termed the "guardians of the pole star". A white bright giant of spectral type A3II-III, with around 4.8 times the Sun's mass, 1,050 times its luminosity and 15 times its radius,{{cite web| first1=James B. | last1=Kaler | title=Pherkad | work=Stars | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/pherkad.html | access-date=18 May 2014 |date=20 December 2013}} it is 487±8 light-years distant from Earth. Pherkad belongs to a class of stars known as Delta Scuti variables—short period (six hours at most) pulsating stars that have been used as standard candles and as subjects to study asteroseismology.{{cite web|url=http://www.aavso.org/vsots_delsct|title=Delta Scuti and the Delta Scuti Variables|last=Templeton|first=Matthew |date=16 July 2010|work=Variable Star of the Season|publisher=AAVSO (American Association of Variable Star Observers)|access-date=19 August 2014}} Also possibly a member of this class is Zeta Ursae Minoris, a white star of spectral type A3V,{{cite web |url = http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Zet+UMi&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title = Zeta Ursae Minoris – Variable Star |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 21 June 2014}} which has begun cooling, expanding and brightening. It is likely to have been a B3 main-sequence star and is now slightly variable.{{cite web| first1=James B. | last1=Kaler | title=Alifa al Farkadain | work=Stars | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/alifa.html | access-date=21 June 2014}} At magnitude 4.95 the dimmest of the seven stars of the Little Dipper is Eta Ursae Minoris. A yellow-white main-sequence star of spectral type F5V, it is 97 light-years distant.{{cite web |url = http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=Eta+Ursae+Minoris&submit=SIMBAD+search |title = Eta Ursae Minoris |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 30 July 2014}} It is double the Sun's diameter, 1.4 times as massive, and shines with 7.4 times its luminosity.{{cite web| first1=James B. | last1=Kaler | title=Anwar al Farkadain | work=Stars | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/anwar.html | access-date=21 June 2014}} Nearby Zeta lies 5.00-magnitude Theta Ursae Minoris. Located 860 ± 80 light-years distant,{{cite web |url = http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=Theta+Ursae+Minoris&submit=SIMBAD+search |title = Theta Ursae Minoris – Variable Star |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 30 July 2014}} it is an orange giant of spectral type K5III that has expanded and cooled off the main sequence, and has an estimated diameter around 4.8 times that of the Sun.{{cite journal | last1=Pasinetti Fracassini | first1=L. E. | last2=Pastori | first2=L. | last3=Covino | first3=S. | last4=Pozzi | first4=A. | title=Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) – Third edition – Comments and statistics | journal=Astronomy and Astrophysics | volume=367 | pages=521–24 |date=February 2001 | issue=2 | doi=10.1051/0004-6361:20000451 | bibcode=2001A&A...367..521P | arxiv=astro-ph/0012289| s2cid=425754 }}

Making up the handle of the Little Dipper are Delta Ursae Minoris, or Yildun,{{cite web | url=https://www.iau.org/public/themes/naming_stars/ | title=Naming Stars |publisher=IAU.org |access-date=8 August 2018}} and Epsilon Ursae Minoris. Just over 3.5 degrees from the north celestial pole, Delta is a white main-sequence star of spectral type A1V with an apparent magnitude of 4.35,{{cite web |url = http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Delta+UMi&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title = Delta Ursae Minoris |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 21 June 2014}} located 172±1 light-years from Earth. It has around 2.8 times the diameter and 47 times the luminosity of the Sun.{{cite web| first1=James B. | last1=Kaler | title=Yildun | work=Stars | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/yildun.html | access-date=30 July 2014}} A triple star system,{{cite web| first1=James B. | last1=Kaler | title=Epsilon Ursae Minoris | work=Stars | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/epsumi.html | access-date=21 June 2014}} Epsilon Ursae Minoris shines with a combined average light of magnitude 4.22.{{cite web |url = http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Eps+UMi&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title = Epsilon Ursae Minoris – Variable of RS CVn type |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 21 June 2014}} A yellow giant of spectral type G5III, the primary is a RS Canum Venaticorum variable star. It is a spectroscopic binary, with a companion 0.36 AU distant, and a third star—an orange main-sequence star of spectral type K0—8100 AU distant.

Located close to Polaris is Lambda Ursae Minoris, a red giant of spectral type M1III. It is a semiregular variable varying between magnitudes 6.35 and 6.45.{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=37416 |title=Lambda Ursae Minoris |author=Watson, Christopher |date=4 January 2010 |work=The International Variable Star Index|publisher=American Association of Variable Star Observers|access-date=21 June 2014}} The northerly nature of the constellation means that the variable stars can be observed all year: The red giant R Ursae Minoris is a semiregular variable varying from magnitude 8.5 to 11.5 over 328 days, while S Ursae Minoris is a long-period variable that ranges between magnitudes 8.0 and 11 over 331 days.{{cite book|last=Levy|first=David H.|title=Observing Variable Stars: A Guide for the Beginner|publisher=Cambridge University Press|location=Cambridge, UK|date=1998|page=133|isbn=978-0-521-62755-9|url=https://books.google.com/books?id=5-O2cd937FMC&pg=PA133}} Located south of Kochab and Pherkad towards Draco is RR Ursae Minoris,{{cite book|author=Arnold, H. J. P.|author2= Doherty, Paul|author3= Moore, Patrick |title=The Photographic Atlas of the Stars|publisher=CRC Press|location=Boca Raton, Florida|date=1999|page=148|isbn=978-0-7503-0654-6|url=https://books.google.com/books?id=YjcvJUfnWBAC&pg=PA148}} a red giant of spectral type M5III that is also a semiregular variable ranging from magnitude 4.44 to 4.85 over a period of 43.3 days.{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=37384 |title=RR Ursae Minoris |author=Otero, Sebastian Alberto |date=16 November 2009 |work=The International Variable Star Index |publisher=American Association of Variable Star Observers|access-date=18 May 2014}} T Ursae Minoris is another red-giant variable star that has undergone a dramatic change in status—from being a long-period (Mira) variable ranging from magnitude 7.8 to 15 over 310–315 days, to being a semiregular variable.{{cite journal|author=Uttenthaler, S.|author2=van Stiphout, K.|author3=Voet, K.|author4=van Winckel, H.|author5=van Eck, S.|author6=Jorissen, A.|author7=Kerschbaum, F.|author8=Raskin, G.|author9=Prins, S.|author10=Pessemier, W.|author11=Waelkens, C.|author12=Frémat, Y.|author13=Hensberge, H.|author14=Dumortier, L.|author15=Lehmann, H.|date=2011|title=The Evolutionary State of Miras with Changing Pulsation Periods|journal=Astronomy and Astrophysics|volume=531|pages=A88|bibcode=2011A&A...531A..88U|arxiv = 1105.2198 |doi = 10.1051/0004-6361/201116463 |s2cid=56226953}} The star is thought to have undergone a shell helium flash—a point where the shell of helium around the star's core reaches a critical mass and ignites—marked by its abrupt change in variability in 1979.{{cite journal|author=Mattei, Janet A.|author2=Foster, Grant|date=1995|title=Dramatic Period Decrease in T Ursae Minoris|journal=The Journal of the American Association of Variable Star Observers|volume=23|issue=2|pages=106–16|bibcode=1995JAVSO..23..106M}} Z Ursae Minoris is a faint variable star that suddenly dropped 6 magnitudes in 1992 and was identified as one of a rare class of stars—R Coronae Borealis variables.{{cite journal|author= Benson, Priscilla J.|author2= Clayton, Geoffrey C.|author3= Garnavich, Peter|author4= Szkody, Paula |title= Z Ursa Minoris – a New R Coronae Borealis Variable |journal= The Astronomical Journal | volume= 108|issue= #1| pages= 247–50 | date=1994 |bibcode=1994AJ....108..247B|doi = 10.1086/117063 |doi-access= free}}

Eclipsing variables are star systems that vary in brightness because of one star passing in front of the other rather than from any intrinsic change in luminosity. W Ursae Minoris is one such system, its magnitude ranging from 8.51 to 9.59 over 1.7 days.{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=37380 |title=W Ursae Minoris |author=Watson, Christopher |date=4 January 2010 |work=The International Variable Star Index |publisher=American Association of Variable Star Observers|access-date=18 July 2015}} The combined spectrum of the system is A2V, but the masses of the two component stars are unknown. A slight change in the orbital period in 1973 suggests there is a third component of the multiple star system—most likely a red dwarf—with an orbital period of 62.2±3.9 years.{{cite journal | title=Period Analysis of Three Close Binary Systems: TW And, TT Her and W UMi |author1=Kreiner, J. M. |author2=Pribulla, T. |author3=Tremko, J. |author4=Stachowski, G. S. |author5=Zakrzewski, B. | journal =Monthly Notices of the Royal Astronomical Society | volume = 383 | issue = #4 |pages= 1506–12|date=2008 |doi=10.1111/j.1365-2966.2007.12652.x |bibcode=2008MNRAS.383.1506K|doi-access=free }} RU Ursae Minoris is another example, ranging from 10 to 10.66 over 0.52 days.{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=37387 |title=RU Ursae Minoris |author=Watson, Christopher |date=4 January 2010 |work=The International Variable Star Index |publisher=American Association of Variable Star Observers|access-date=18 July 2015}} It is a semidetached system, as the secondary star is filling its Roche lobe and transferring matter to the primary.{{cite journal|title=A Photometric Study of the Near-contact System RU Ursae Minoris |author1=Manimanis, V. N. |author2=Niarchos, P. G. | journal=Astronomy and Astrophysics |volume=369 |issue=3 |pages=960–64 |date=2001|doi=10.1051/0004-6361:20010178 |bibcode=2001A&A...369..960M|doi-access=free }}

RW Ursae Minoris is a cataclysmic variable star system that flared up as a nova in 1956, reaching magnitude 6. In 2003, it was still two magnitudes brighter than its baseline, and dimming at a rate of 0.02 magnitude a year. Its distance has been calculated as 5,000±800 parsecs (16,300 light-years), which puts its location in the galactic halo.{{cite journal |title = RW Ursae Minoris (1956): An Evolving Postnova System |author =Bianchini, A. |author2 =Tappert, C. |author3 = Canterna, R. |author4 =Tamburini, F. |author5 =Osborne, H. |author6 =Cantrell, K. |journal= Publications of the Astronomical Society of the Pacific |volume =115 |issue= #809 | pages = 811–18 | bibcode=2003PASP..115..811B|doi = 10.1086/376434 |year =2003 |doi-access =free }}

Taken from the villain in The Magnificent Seven, Calvera is the nickname given to an X-ray source known as 1RXS J141256.0+792204 in the ROSAT All-Sky Survey Bright Source Catalog (RASS/BSC).{{cite news|url=http://news.bbc.co.uk/2/hi/science/nature/6955769.stm|title=Rare Dead Star Found Near Earth|publisher=BBC |work= BBC News: Science/Nature |date=20 August 2007|access-date=21 August 2007|archive-date=13 July 2014 |archive-url=https://web.archive.org/web/20140713133234/http://news.bbc.co.uk/2/hi/science/nature/6955769.stm|url-status=live}} It has been identified as an isolated neutron star, one of the closest of its kind to Earth.{{cite journal| author=Rutledge, Robert| author2=Fox, Derek| author3=Shevchuk, Andrew |date=2008 |title=Discovery of an Isolated Compact Object at High Galactic Latitude | journal=The Astrophysical Journal| volume= 672| issue= #2 |pages= 1137–43 |bibcode=2008ApJ...672.1137R|arxiv = 0705.1011 |doi = 10.1086/522667 | s2cid=7915388}} Ursa Minor has two enigmatic white dwarfs. Documented on January 27, 2011, H1504+65 is a faint (magnitude 15.9) star with the hottest surface temperature—200,000 K—yet discovered for a white dwarf. Its atmosphere, composed of roughly half carbon, half oxygen and 2% neon, is devoid of hydrogen and helium—its composition unexplainable by current models of stellar evolution.{{cite journal|last=Werner|first=K.|author2=Rauch, T.|date=2011|title=UV Spectroscopy of the Hot Bare Stellar Core H1504+65 with the HST Cosmic Origins Spectrograph|journal=Astrophysics and Space Science|volume=335|issue=1|pages=121–24|doi=10.1007/s10509-011-0617-x|bibcode = 2011Ap&SS.335..121W |s2cid=116910726}} WD 1337+705 is a cooler white dwarf that has magnesium and silicon in its spectrum, suggesting a companion or circumstellar disk, though no evidence for either has come to light.{{cite journal|author1=Dickinson, N. J. |author2=Barstow, M. A. |author3=Welsh, B. Y. |author4=Burleigh, M. |author5=Farihi, J. |author6=Redfield, S. |author7=Unglaub, K. |date=2012|title=The Origin of Hot White Dwarf Circumstellar Features|journal=Monthly Notices of the Royal Astronomical Society |volume=423|issue=2|pages=1397–1410| doi=10.1111/j.1365-2966.2012.20964.x |doi-access=free |bibcode=2012MNRAS.423.1397D|arxiv = 1203.5226 |s2cid=119212643 }} WISE 1506+7027 is a brown dwarf of spectral type T6 that is a mere {{val|11.1|+2.3|-1.3}} light-years away from Earth.{{cite journal | last=Marsh |first=Kenneth A. | author2=Wright, Edward L. | author3=Kirkpatrick, J. Davy | author4=Gelino, Christopher R. | author5=Cushing, Michael C. | author6=Griffith, Roger L. | author7=Skrutskie, Michael F. | author8=Eisenhardt, Peter R. | date=2013 | title=Parallaxes and Proper Motions of Ultracool Brown Dwarfs of Spectral Types Y and Late T | journal=The Astrophysical Journal | volume=762 | issue=2 | pages=119 | arxiv=1211.6977 | bibcode=2013ApJ...762..119M | doi=10.1088/0004-637X/762/2/119|s2cid=42923100 }} A faint object of magnitude 14, it was discovered by the Wide-field Infrared Survey Explorer (WISE) in 2011.{{cite journal |doi=10.1088/0067-0049/197/2/19 |author-link=J. Davy Kirkpatrick |last1=Kirkpatrick |first1=J. Davy |last2=Cushing |first2=Michael C. |last3=Gelino |first3=Christopher R. |last4=Griffith |first4=Roger L. |last5=Skrutskie |first5=Michael F. |last6=Marsh |first6=Kenneth A. |last7=Wright |first7=Edward L. |last8=Mainzer |first8=Amy K. |last9=Eisenhardt |first9=Peter R. |last10=McLean |first10=Ian S. |last11=Thompson |first11=Maggie A. |last12=Bauer |first12=James M. |last13=Benford |first13=Dominic J. |last14=Bridge |first14=Carrie R. |last15=Lake |first15=Sean E. |last16=Petty |first16=Sara M. |last17=Stanford |first17=Spencer Adam |last18=Tsai |first18=Chao-Wei |last19=Bailey |first19=Vanessa |last20=Beichman |first20=Charles A. |last21=Bloom |first21=Joshua S. |last22=Bochanski |first22=John J. |last23=Burgasser |first23=Adam J. |last24=Capak |first24=Peter L. |last25=Cruz |first25=Kelle L. |last26=Hinz |first26=Philip M. |last27=Kartaltepe |first27=Jeyhan S. |last28=Knox |first28=Russell P. |last29=Manohar |first29=Swarnima |last30=Masters |first30=Daniel |last31=Morales-Calderon |first31=Maria |last32=Prato |first32=Lisa A. |last33=Rodigas |first33=Timothy J. |last34=Salvato |first34=Mara |last35=Schurr |first35=Steven D. |last36=Scoville |first36=Nicholas Z. |last37=Simcoe |first37=Robert A. |last38=Stapelfeldt |first38=Karl R. |last39=Stern |first39=Daniel |last40=Stock |first40=Nathan D. |last41=Vacca |first41=William D. |title=The First Hundred Brown Dwarfs Discovered by the Wide-field Infrared Survey Explorer (WISE) |date=2011 |journal=The Astrophysical Journal Supplement |volume=197 |issue=2 |pages=19 |arxiv=1108.4677v1 |bibcode=2011ApJS..197...19K |s2cid=16850733 }}

Kochab aside, three more stellar systems have been discovered to contain planets. 11 Ursae Minoris is an orange giant of spectral type K4III around 1.8 times as massive as the Sun. Around 1.5 billion years old, it has cooled and expanded since it was an A-type main-sequence star. Around 390 light-years distant, it shines with an apparent magnitude of 5.04. A planet around 11 times the mass of Jupiter was discovered in 2009 orbiting the star with a period of 516 days.{{cite journal | title=Planetary Companions around the K Giant Stars 11 Ursae Minoris and HD 32518 | last1=Döllinger | first1=M. P. | last2=Hatzes | first2=A.P. | last3=Pasquini | first3=L. | last4=Guenther | first4=E. W. | last5=Hartmann | first5=M. | journal=Astronomy and Astrophysics | volume=505 | issue=3 | pages=1311–17 | date=2009 | arxiv=0908.1753 | bibcode=2009A&A...505.1311D | doi=10.1051/0004-6361/200911702 | s2cid=9686080 }} HD 120084 is another evolved star, a yellow giant of spectral type G7III, around 2.4 times the mass of the Sun. It has a planet 4.5 times the mass of Jupiter, with one of the most eccentric planetary orbits (e = 0.66), discovered by precisely measuring the radial velocity of the star in 2013.{{cite journal | arxiv=1304.4328 |title=Planetary Companions to Three Evolved Intermediate-Mass Stars: HD 2952, HD 120084, and omega Serpentis| url=https://archive.org/details/arxiv-1304.4328 |author= Sato, Bun'ei|author2= Omiya, Masashi|author3= Harakawa, Hiroki|author4= Liu, Yu-Juan|author5= Izumiura, Hideyuki|author6= Kambe, Eiji|author7= Takeda, Yoichi|author8= Yoshida, Michitoshi|author9= Itoh, Yoichi|author10= Ando, Hiroyasu|author11= Kokubo, Eiichiro|author12= Ida, Shigeru | journal= Publications of the Astronomical Society of Japan |pages = [https://archive.org/details/arxiv-1304.4328/page/n0 1]–15 |date=2013|volume=65|issue=4|bibcode = 2013PASJ...65...85S |doi = 10.1093/pasj/65.4.85 |s2cid=119248666}} HD 150706 is a sunlike star of spectral type G0V some 89 light-years distant from the Solar System. It was thought to have a planet as massive as Jupiter at a distance of 0.6 AU, but this was discounted in 2007.{{cite journal|author=Wright, J.T.|author2=Marcy, G.W.|author3=Fischer, D. A.|author4=Butler, R. P.|author5=Vogt, S. S.|author6=Tinney, C. G.|author7=Jones, H. R. A.|author8=Carter, B. D.|author9=Johnson, J. A.|author10=McCarthy, C.|author11=Apps, K.|date=2007|title=Four New Exoplanets and Hints of Additional Substellar Companions to Exoplanet Host Stars|journal=The Astrophysical Journal|volume=657|issue=1|pages=533–45|doi=10.1086/510553 |bibcode=2007ApJ...657..533W|arxiv = astro-ph/0611658 |s2cid=35682784}} A further study published in 2012 showed that it has a companion around 2.7 times as massive as Jupiter that takes around 16 years to complete an orbit and is 6.8 AU distant from its star.{{citation |doi=10.1051/0004-6361/201118419 |arxiv=1205.5835 |url=http://www.aanda.org/articles/aa/full_html/2012/09/aa18419-11/aa18419-11.html |title=The SOPHIE search for northern extrasolar planets V. Follow-up of ELODIE candidates: Jupiter-analogs around Sun-like stars |year=2012 |last1=Boisse |first1=Isabelle |last2=Pepe |first2=Francesco |last3=Perrier |first3=Christian |last4=Queloz |first4=Didier |last5=Bonfils |first5=Xavier |last6=Bouchy |first6=François |last7=Santos |first7=Nuno C. |last8=Arnold |first8=Luc |last9=Beuzit |first9=Jean-Luc |last10=Dìaz |first10=Rodrigo F. |last11=Delfosse |first11=Xavier |last12=Eggenberger |first12=Anne |last13=Ehrenreich |first13=David |last14=Forveille |first14=Thierry |last15=Hébrard |first15=Guillaume |last16=Lagrange |first16=Anne-Marie |last17=Lovis |first17=Christophe |last18=Mayor |first18=Michel |last19=Moutou |first19=Claire |last20=Naef |first20=Dominique |last21=Santerne |first21=Alexandre |last22=Ségransan |first22=Damien |last23=Sivan |first23=Jean-Pierre |last24=Udry |first24=Stéphane |journal=Astronomy and Astrophysics |volume=545 |pages=A55 |bibcode=2012A&A...545A..55B |s2cid=119109836 }}

File:NGC 6217 hs-2009-25-bc-full.jpg

Ursa Minor is rather devoid of deep-sky objects. The Ursa Minor Dwarf, a dwarf spheroidal galaxy, was discovered by Albert George Wilson of the Lowell Observatory in the Palomar Sky Survey in 1955.{{cite book|last=Bergh|first=Sidney |title=The Galaxies of the Local Group|publisher=Cambridge University Press|location=Cambridge, UK|date=2000|page=257|isbn=978-1-139-42965-8|url=https://books.google.com/books?id=H0JMeoqFqEcC&q=variable+stars+ursa+minor&pg=PA257}} Its centre is around {{val|225,000}} light-years distant from Earth.{{cite journal|author=Grebel, Eva K.|author2=Gallagher, John S., III|author3=Harbeck, Daniel|title=The Progenitors of Dwarf Spheroidal Galaxies|journal=The Astronomical Journal|date=2003|volume=125|issue=4|pages=1926–39|doi=10.1086/368363 | bibcode=2003AJ....125.1926G|arxiv = astro-ph/0301025 |s2cid=18496644}} In 1999, Kenneth Mighell and Christopher Burke used the Hubble Space Telescope to confirm that the galaxy had had a single burst of star formation that took place around 14 billion years ago and lasted around 2 billion years,{{Cite journal | last1 = van den Bergh | first1 = Sidney | author-link1 = Sidney van den Bergh | title = Updated Information on the Local Group | date = April 2000 | journal = The Publications of the Astronomical Society of the Pacific | volume = 112 | issue = #770 | bibcode = 2000PASP..112..529V | pages = 529–36 | doi = 10.1086/316548 |arxiv = astro-ph/0001040 | s2cid = 1805423 }} and that the galaxy was probably as old as the Milky Way itself.{{cite journal|author=Mighell, Kenneth J.|author2=Burke, Christopher J.|date=1999|title=WFPC2 Observations of the Ursa Minor Dwarf Spheroidal Galaxy|journal=The Astronomical Journal|volume=118|issue=366|pages=366–380|doi=10.1086/300923|arxiv = astro-ph/9903065 |bibcode = 1999AJ....118..366M |s2cid=119085245}}

NGC 3172 (also known as Polarissima Borealis) is a faint, magnitude-14.9 galaxy that happens to be the closest NGC object to the north celestial pole.{{Cite web|title=NGC 3172|url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=%40331138&Name=NGC++3172&submit=display+all+measurements#lab_meas%20SIMBAD:%20NGC%203054%20--%20Galaxy|website=sim-id|access-date=2020-05-29}} It was discovered by John Herschel in 1831.{{Cite web|title=New General Catalog Objects: NGC 3150 - 3199|url=https://cseligman.com/text/atlas/ngc31a.htm#3172|website=cseligman.com|access-date=2020-05-30}}

NGC 6217 is a barred spiral galaxy located some 67 million light-years away,{{Cite journal | last1 = Gusev | first1 = A. S. | last2 = Pilyugin | first2 = L. S. | last3 = Sakhibov | first3 = F. | last4 = Dodonov | first4 = S. N. | last5 = Ezhkova | first5 = O. V. | last6 = Khramtsova | first6 = M. S. | last7 = Garzónhuhed | first7 = F. | title = Oxygen and Nitrogen Abundances of H II regions in Six Spiral Galaxies | journal = Monthly Notices of the Royal Astronomical Society | volume = 424 | issue = #3 | pages = 1930–40 |date=2012 | arxiv = 1205.3910 | doi = 10.1111/j.1365-2966.2012.21322.x | doi-access = free | bibcode = 2012MNRAS.424.1930G| s2cid = 118437910 }} which can be located with a {{Convert|4|in|cm|abbr=on|order=flip}} or larger telescope as an 11th-magnitude object about 2.5° east-northeast of Zeta Ursae Minoris.{{Cite book | first1 = Stephen James | last1= O'Meara | title= Steve O'Meara's Herschel 400 Observing Guide | publisher = Cambridge University Press |location=Cambridge, UK| page= 227 | date = 2007 | isbn= 978-0-521-85893-9 | url = https://books.google.com/books?id=Nyh9fAC_tpIC&pg=PA227}} It has been characterized as a starburst galaxy, which means it is undergoing a high rate of star formation compared with a typical galaxy.{{cite journal|last= Calzetti|first=Daniela|author-link= Daniela Calzetti |date=1997|title=Reddening and Star Formation in Starburst Galaxies|journal=Astronomical Journal|volume=113|pages=162–84|doi=10.1086/118242 | bibcode=1997AJ....113..162C|arxiv = astro-ph/9610184 |s2cid=16526015}}

NGC 6251 is an active supergiant elliptical radio galaxy more than 340 million light-years away from Earth. It has a Seyfert 2 active galactic nucleus, and is one of the most extreme examples of a Seyfert galaxy. This galaxy may be associated with gamma-ray source 3EG J1621+8203, which has high-energy gamma-ray emission.{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=QSO+B1637%2B826 |title = NGC 6251 – Seyfert 2 Galaxy |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 21 July 2015}} It is also noted for its one-sided radio jet—one of the brightest known—discovered in 1977.{{cite journal|author1=Perley, R. A. |author2=Bridle, A. H. |author3=Willis, A. G. |date=1984|title=High-resolution VLA Observations of the Radio Jet in NGC 6251|journal=Astrophysical Journal Supplement Series|volume=54|pages=291–334|doi=10.1086/190931 | bibcode=1984ApJS...54..291P}}

The Ursids, a prominent meteor shower that occurs in Ursa Minor, peaks between December 18 and 25. Its parent body is the comet 8P/Tuttle.{{cite journal |last = Jenniskens |first = Peter |date = September 2012 |title = Mapping Meteoroid Orbits: New Meteor Showers Discovered | journal = Sky & Telescope |page = 24}}

• Polaris Flare
• Ursa Minor Beta, fictional planet in The Hitchhiker's Guide to the Galaxy
• Ursa Minor (Chinese astronomy)

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• [http://www.allthesky.com/constellations/ursaminor/ The Deep Photographic Guide to the Constellations: Ursa Minor]
• [http://astrojan.nhely.hu/ursami.htm The clickable Ursa Minor]
• [https://iconographic.warburg.sas.ac.uk/category/vpc-taxonomy-017039 Warburg Institute Iconographic Database (ca 160 medieval and early modern images of Ursa Minor)]

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{{Stars of Ursa Minor}}

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Category:Constellations

Category:Northern constellations

Category:Constellations listed by Ptolemy