View source for Astronomy:Omicron Ursae Majoris

{{short description|Star in the constellation Ursa Major}}
{{Starbox begin
 | name = Omicron Ursae Majoris
}}
{{Starbox image
| image = {{Location map|100x100
|AlternativeMap=Ursa Major IAU.svg
|caption=
|alt=Diagram showing star positions and boundaries of the Ursa Major constellation and its surroundings
|width=320
|lat=76 |long=72
|mark=Cercle rouge 100%.svg | marksize=12
|float=center
}}| caption=Location of ο Ursa Major (circled)
}}
{{Starbox observe
 | epoch    = [[Astronomy:J2000.0|J2000.0]]
 | constell = [[Astronomy:Ursa Major|Ursa Major]]
 | ra       = {{RA|08|30|15.87064}}<ref name=aaa474_2_653/>
 | dec      = {{DEC|+60|43|05.4115}}<ref name=aaa474_2_653/>
 | appmag_v = +3.35<ref name=aaa352_495/>
}}
{{Starbox character
 | class    = G5III:<ref name=perkins/>
 | b-v      = +0.85<ref name=clpl4/>
 | u-b      = +0.52<ref name=clpl4/>
 | variable = 
}}
{{Starbox astrometry
 | radial_v = +19.8<ref name=gcsrv/>
 | prop_mo_ra  = -133.644<ref name=edr3>{{Cite Gaia EDR3|1041808368494264576}}</ref>
 | prop_mo_dec = -107.664<ref name=edr3/>
 | parallax = 17.9335
 | p_error  = 0.1456
 | parallax_footnote = <ref name=edr3/>
 | absmag_v = –0.40<ref name=pasj60_4_781/>
}}
{{Starbox detail
 | mass     = 3.09<ref name=pasj60_4_781/>
 | radius   = 14<ref name=lang2006/>
 | gravity  = 2.64<ref name=pasj60_4_781/>
 | metal_fe = –0.09<ref name=pasj60_4_781/>
 | age_myr  = {{nowrap|360 ± 30}}<ref name=aaa480_1_91/>
 | luminosity  = 138<ref name=pasj60_4_781/>
 | temperature = 5,242<ref name=pasj60_4_781/>
 | rotational_velocity = 3.83<ref name="Sato2012"/>
}}
{{Starbox catalog
 | names = Muscida, ο&nbsp;Ursae Majoris, ο&nbsp;UMa, Omicron&nbsp;UMa, 1&nbsp;Ursae Majoris, [[Astronomy:Star catalogue#BD/CD/CPD|BD]]+61&nbsp;1054, CCDM&nbsp;J08303+6043A, FK5&nbsp;317, [[Astronomy:Boss General Catalogue|GC]]&nbsp;11593, HD&nbsp;71369, [[Astronomy:Hipparcos#Published catalogues|HIP]]&nbsp;41704, [[Astronomy:Bright Star Catalogue|HR]]&nbsp;3323, [[Astronomy:PPM Star Catalogue|PPM]]&nbsp;16654, [[Astronomy:Smithsonian Astrophysical Observatory Star Catalog|SAO]]&nbsp;14573, [[Astronomy:Washington Double Star Catalog|WDS]]&nbsp;J08303+6043A, [[Astronomy:2MASS|2MASS]] J08301592+6043056, Gaia EDR3 1041808368494264576<ref name=SIMBAD/>
}}
{{Starbox reference
| Simbad = Omi+UMa
}}
{{Starbox end}}

'''Omicron Ursae Majoris''' ('''ο&nbsp;Ursae Majoris''', abbreviated '''Omicron&nbsp;UMa''', '''ο&nbsp;UMa'''), formally named '''Muscida''' {{IPAc-en|'|m|juː|s|I|d|@}},<ref name=Kunitzsch>{{cite book
  |last1=Kunitzsch |first1=Paul
  |last2=Smart |first2=Tim
  |date = 2006  |edition = 2nd rev.
  |title = A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations
  |publisher = Sky Pub |location = Cambridge, Massachusetts
  |isbn = 978-1-931559-44-7
}}</ref><ref name="IAU-CSN">{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |access-date=28 July 2016}}</ref> is a [[Astronomy:Star system|star system]] in the northern [[Astronomy:Circumpolar constellation|circumpolar constellation]] of [[Astronomy:Ursa Major|Ursa Major]]. It has an [[Astronomy:Apparent visual magnitude|apparent visual magnitude]] of +3.35<ref name=aaa352_495/> and is located at a distance of around {{Convert|179|ly|pc|abbr=off|lk=on}} from the [[Astronomy:Sun|Sun]].<ref name=aaa474_2_653/> In 2012, an [[Astronomy:Exoplanet|exoplanet]] designated Omicron Ursae Majoris Ab was found to be orbiting the primary.<ref name="Sato2012"/>

==Nomenclature==
''ο&nbsp;Ursae Majoris'' ([[Social:Latinisation of names|Latinised]] to ''Omicron Ursae Majoris'') is the star's [[Astronomy:Bayer designation|Bayer designation]].

The traditional name ''Muscida'' was shared with the optical [[Astronomy:Double star|double star]] [[Astronomy:Pi Ursae Majoris|Pi Ursae Majoris]]. In 2016, the [[Organization:International Astronomical Union|International Astronomical Union]] organized a [[Astronomy:IAU Working Group on Star Names|Working Group on Star Names]] (WGSN)<ref name="WGSN">{{cite web | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN)|access-date=22 May 2016}}</ref> to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016<ref name="WGSN1">{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf | title=Bulletin of the IAU Working Group on Star Names, No. 1 |access-date=28 July 2016}}</ref> included a table of the first two batches of names approved by the WGSN; which included ''Muscida'' for this star.

In [[Astronomy:Chinese astronomy|Chinese]], {{lang|zh|內階}} ({{lang|zh-Latn|Nèi Jiē}}), meaning ''[[Astronomy:Purple Forbidden enclosure|Inner Steps]]'', refers to an [[Astronomy:Asterism|asterism]] consisting of ο Ursae Majoris, 16 Ursae Majoris, 6 Ursae Majoris, [[Astronomy:23 Ursae Majoris|23 Ursae Majoris]], 5 Ursae Majoris and 17 Ursae Majoris. Consequently, the [[Astronomy:Chinese star names|Chinese name]] for ο Ursae Majoris itself is {{lang|zh|內階一}} ({{lang|zh-Latn|Nèi Jiē yī}}, {{lang-en|the First Star of Inner Steps}}.).<ref>{{in lang|zh}} [http://aeea.nmns.edu.tw/2006/0606/ap060616.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 16 日]</ref>

==Properties and observations==
The [[Astronomy:Stellar classification|stellar classification]] of this star, G5&nbsp;III, indicates that it is in the [[Astronomy:Giant star|giant]] stage of its [[Astronomy:Stellar evolution|evolution]]. The [[Astronomy:Interferometry|interferometry]]-measured [[Astronomy:Angular diameter|angular diameter]] of this star is about 2.42&nbsp;mas,<ref name=aaa431_773/> which, at its estimated distance, equates to a physical radius of about 14 times the [[Astronomy:Solar radius|radius of the Sun]].<ref name=lang2006/> It has about three<ref name=pasj60_4_781/> times the mass of the Sun and radiates 138<ref name=pasj60_4_781/> times the Sun's luminosity from its [[Astronomy:Stellar atmosphere|outer atmosphere]] at an [[Astronomy:Effective temperature|effective temperature]] of 5,282&nbsp;K,<ref name=aaa352_495/> giving it the yellowish hue of a G-type star.<ref name=csiro/>

In 1963, East German astronomer Gerhard Jakisch reported this star as a [[Astronomy:Variable star|variable]] with a period of 358 days and an amplitude of 0.08 magnitude. The 1982 edition of the ''[[Astronomy:New Catalogue of Suspected Variable Stars|New Catalogue of Suspected Variable Stars]]'' listed it with a variability from 3.30 to 3.36 in the visual band. However, in 1992 American astronomer Dorrit Hoffleit noted that the two comparison stars used to determine the variability may themselves be variable. Hence the actual variability of this star may be suspect.<ref name=ibvs3789/>

Muscida has a magnitude 15.2 common proper motion companion at an angular separation of 7.1&nbsp;[[Arcsecond|arcsecond]]s.<ref name=mnras389_2_869/> With a probability of 99.4%, this companion is the source for the X-ray emission from the system.<ref name=apjss184_1_138/> Omicron Ursae Majoris is sometimes listed with two more companions, but, based on [[Astronomy:Proper motion|proper motion]] data, these appear to be optical companions. No other companions were detected by 2016.<ref>{{cite journal|arxiv=1601.01524|title=A lucky imaging multiplicity study of exoplanet host stars II|year=2016|doi=10.1093/mnras/stw049|last1=Ginski|first1=C.|last2=Mugrauer|first2=M.|last3=Seeliger|first3=M.|last4=Buder|first4=S.|last5=Errmann|first5=R.|last6=Avenhaus|first6=H.|last7=Mouillet|first7=D.|last8=Maire|first8=A.-L.|last9=Raetz|first9=S.|journal=Monthly Notices of the Royal Astronomical Society|volume=457|issue=2|pages=2173–2191|bibcode=2016MNRAS.457.2173G |s2cid=53626523}}</ref>

This system is a member of the thin disk population and is following an orbit through the [[Astronomy:Milky Way|Milky Way]] galaxy with an [[Astronomy:Orbital eccentricity|eccentricity]] of 0.12. It comes as close to the [[Galactic Center]] as {{Convert|23.5|kly|kpc|abbr=on}} and as distant as {{Convert|30.2|kly|kpc|abbr=on}}. This orbit carries it no more than about 330&nbsp;ly (100&nbsp;pc) above the [[Astronomy:Galactic plane|galactic plane]].<ref name=aaa480_1_91/> It is considered a [[Astronomy:Runaway star|runaway star]] because it has a high [[Astronomy:Peculiar velocity|peculiar velocity]] of 35.5&nbsp;km s<sup>−1</sup> relative to the typical motion of stars in its vicinity.<ref name=mnras410_1_190/>

The star has no detectable magnetic fields.<ref>{{cite journal|arxiv=1701.02891|year=2017|title=High-resolution Spectroscopy and Spectropolarimetry of Selected δ-Sct Pulsating Variables|doi=10.1093/mnras/stx087|last1=Joshi|first1=Santosh|last2=Semenko|first2=Eugene|last3=Moiseeva|first3=A.|last4=Sharma|first4=Kaushal|last5=Joshi|first5=Y. C.|last6=Sachkov|first6=M.|last7=Singh|first7=Harinder P.|last8=Kumar|first8=Yerra Bharat|journal=Monthly Notices of the Royal Astronomical Society|pages=stx087|s2cid=119006112}}</ref>

==Planetary system==
In 2012, an [[Astronomy:Exoplanet|exoplanet]] designated Omicron Ursae Majoris Ab and orbiting the primary at 3.9 astronomical units, was found. This gas giant (4.1 times as massive as Jupiter) completes an orbit in 1630 days.<ref name="Sato2012"/>

{{OrbitboxPlanet begin
| table_ref = <ref name="Sato2012"/>
}}
{{OrbitboxPlanet
| exoplanet = b
| mass = >4.1
| period = 1630±35
| semimajor = 3.9
| eccentricity = 0.130 ± 0.065
}}
{{Orbitbox end}}

==References==
{{Reflist|refs=

<ref name=perkins>{{cite journal
 | title=The Perkins catalog of revised MK types for the cooler stars
 | journal=Astrophysical Journal Supplement Series
 | last1=Keenan | first1=Philip C. | last2=McNeil | first2=Raymond C.
 | volume=71 |pages=245 | year=1989
 | bibcode=1989ApJS...71..245K | doi=10.1086/191373 | s2cid=123149047
 }}</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 }}</ref>

<ref name=aaa352_495>{{cite journal | last1=Mallik | first1=Sushma V. | title=Lithium abundance and mass | journal=Astronomy and Astrophysics | volume=352 | pages=495–507 |date=December 1999 | bibcode=1999A&A...352..495M }}</ref>

<ref name=gcsrv>{{cite journal | last=Wilson | first=Ralph Elmer | date=1953 | title=General Catalogue of Stellar Radial Velocities | journal=Carnegie Institute Washington D.C. Publication | publisher=Carnegie Institution of Washington | location=Washington | bibcode=1953GCRV..C......0W }}</ref>

<ref name=clpl4>{{cite journal | display-authors=1 | last1=Johnson | first1=H. L. | last2=Iriarte | first2=B. | last3=Mitchell | first3=R. I. | last4=Wisniewskj | first4=W. Z. | title=UBVRIJKL photometry of the bright stars | journal=Communications of the Lunar and Planetary Laboratory | volume=4 | issue=99 | pages=99 | date=1966 | bibcode=1966CoLPL...4...99J }}</ref>

<ref name=pasj60_4_781>{{cite journal | last1=Takeda | first1=Yoichi | last2=Sato | first2=Bun'ei | last3=Murata | first3=Daisuke | title=Stellar parameters and elemental abundances of late-G giants | journal=Publications of the Astronomical Society of Japan | volume=60 | issue=4 | pages=781–802 |date=August 2008 | bibcode=2008PASJ...60..781T |arxiv = 0805.2434 | doi=10.1093/pasj/60.4.781| s2cid=16258166 }}</ref>

<ref name=SIMBAD>{{cite simbad | title=bet CMi | access-date=2012-01-09 }}</ref>

<ref name=aaa480_1_91>{{cite journal | display-authors=1 | last1=Soubiran | first1=C. | last2=Bienaymé | first2=O. | last3=Mishenina | first3=T. V. | last4=Kovtyukh | first4=V. V. | title=Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants | journal=Astronomy and Astrophysics | date=2008 | volume=480 | issue=1 | pages=91–101 | bibcode=2008A&A...480...91S | doi=10.1051/0004-6361:20078788 |arxiv = 0712.1370 | s2cid=16602121 }}</ref>

<ref name=mnras410_1_190>{{cite journal | last1=Tetzlaff | first1=N. | last2=Neuhäuser | first2=R. | last3=Hohle | first3=M. M. | title=A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun | journal=[[Organization:Monthly Notices of the Royal Astronomical Society|Monthly Notices of the Royal Astronomical Society]] | volume=410 | issue=1 | pages=190–200 |date=January 2011 | doi=10.1111/j.1365-2966.2010.17434.x | bibcode=2011MNRAS.410..190T |arxiv = 1007.4883 | s2cid=118629873 }}</ref>

<ref name=aaa431_773>{{cite journal | last1=Richichi | first1=A. | last2=Percheron | first2=I. | last3=Khristoforova | first3=M. | title=CHARM2: An updated Catalog of High Angular Resolution Measurements | journal=Astronomy and Astrophysics | volume=431 | issue=2 | pages=773–777 |date=February 2005 | doi=10.1051/0004-6361:20042039 | bibcode=2005A&A...431..773R | doi-access=free }}</ref>

<ref name=lang2006>{{cite book | first1=Kenneth R. | last1=Lang | title=Astrophysical formulae | volume=1 | series=Astronomy and astrophysics library | edition=3rd | publisher=Birkhäuser | date=2006 | isbn=3-540-29692-1 | url=https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41 }}. The radius (R<sub>*</sub>) is given by:
:<math>\begin{align} 2\cdot R_*
 & = \frac{(10^{-3}\cdot 54.9\cdot 2.42)\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\
 & \approx 28.6\cdot R_{\bigodot}
\end{align}</math></ref>

<ref name=csiro>{{cite web | title=The Colour of Stars | date=December 21, 2004 | work=Australia Telescope, Outreach and Education | publisher=Commonwealth Scientific and Industrial Research Organisation | url=http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html | access-date=2012-01-16 | archive-url=https://web.archive.org/web/20120318151427/http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html | archive-date=March 18, 2012 | url-status=dead }}</ref>

<ref name=ibvs3789>{{cite journal | last1=Hoffleit | first1=D. | title=Do all Three Vary: omicron UMa, 23 UMa and HR 3245? | journal=Information Bulletin on Variable Stars | volume=3789 | page=1 |date=October 1992 | bibcode=1992IBVS.3789....1H }}</ref>

<ref name=mnras389_2_869>{{cite journal | last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A. | title=A catalogue of multiplicity among bright stellar systems | journal=Monthly Notices of the Royal Astronomical Society | volume=389 | issue=2 | pages=869–879 |date=September 2008 | doi=10.1111/j.1365-2966.2008.13596.x | bibcode=2008MNRAS.389..869E |arxiv = 0806.2878 | s2cid=14878976 }}</ref>

<ref name=apjss184_1_138>{{cite journal | last1=Haakonsen | first1=Christian Bernt | last2=Rutledge | first2=Robert E. | title=XID II: Statistical Cross-Association of ROSAT Bright Source Catalog X-ray Sources with 2MASS Point Source Catalog Near-Infrared Sources | journal=The Astrophysical Journal Supplement |volume=184 | issue=1 | pages=138–151 |date=September 2009 | doi=10.1088/0067-0049/184/1/138 | bibcode=2009ApJS..184..138H |arxiv = 0910.3229 | s2cid=119267456 }}</ref>

<ref name="Sato2012">{{cite journal | title=Substellar Companions to Seven Evolved Intermediate-Mass Stars | last1=Sato | first1=Bun'ei | last2=Omiya | first2=Masashi | last3=Harakawa | first3=Hiroki | last4=Izumiura | first4=Hideyuki | last5=Kambe | first5=Eiji | last6=Takeda | first6=Yoichi | last7=Yoshida | first7=Michitoshi | last8=Itoh | first8=Yoichi | last9=Ando | first9=Hiroyasu | last10=Kokubo | first10=Eiichiro | last11=Ida | first11=Shigeru | display-authors=1 | journal=Publications of the Astronomical Society of Japan | volume=64 | issue=6 | at=135 | year=2012 | arxiv=1207.3141 | bibcode=2012PASJ...64..135S | doi=10.1093/pasj/64.6.135 | s2cid=119197073 }}</ref>

}}

{{Stars of Ursa Major}}
<!-- Properties -->
[[Category:G-type giants]]
[[Category:Planetary systems with one confirmed planet]]
[[Category:Binary stars]]
[[Category:Runaway stars]]
<!-- Identifiers -->
[[Category:Bayer objects|Ursae Majoris, Omicron]]
[[Category:Durchmusterung objects]]
[[Category:Flamsteed objects|Ursae Majoris, 01]]
[[Category:Hipparcos objects|041704]]
[[Category:Henry Draper Catalogue objects|071369]]
[[Category:Bright Star Catalogue objects|3323]]
[[Category:Stars with proper names|Muscida]]
[[Category:2MASS objects|J08301592+6043056]]

{{Sourceattribution|Omicron Ursae Majoris}}