4 Ursae Majoris: Difference between revisions

| name = Pi²² Ursae Majoris

}}| caption=Location of π²² Ursae Majoris (circled) near the center

| prop_mo_ra = –60−60.05<ref name=aaa474_2_653/>

| names = π²²&nbsp;Ursae Majoris, π²²&nbsp;UMa, Pi²²&nbsp;UMa, 4&nbsp;Ursae Majoris, [[Star catalogue#BD/CD/CPD|BD]]+64°698, [[Fifth Fundamental Catalogue|FK5]]&nbsp;2677, [[Boss General Catalogue|GC]]&nbsp;11850, [[Henry Draper Catalogue|HD]]&nbsp;73108, [[Hipparcos catalogue|HIP]]&nbsp;42527, [[Bright Star Catalogue|HR]]&nbsp;3403, [[PPM Star Catalogue|PPM]]&nbsp;16713, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]]&nbsp;14616.

'''4 Ursae Majoris''' (sometimes abbreviated '''4 UmaUMa''') is the [[Flamsteed designation]] of a [[star]] in the [[Northern celestial hemisphere|northern]] [[circumpolar constellation]] of [[Ursa Major]]. It also bears the [[Bayer designation]] of '''Pi²² Ursae Majoris''' ('''Pi²²&nbsp;UMa''', '''π²²&nbsp;Ursae Majoris''', '''π²²&nbsp;UMa''') and is traditionally named [[Muscida]]. With an [[apparent visual magnitude]] of +4.6,<ref name=mnras172_667/> this star is visible from suburban or darker skies based upon the [[Bortle Dark-Sky Scale]]. From [[parallax]] measurements made during the ''[[Hipparcos]]'' mission, this star is at a distance of {{Convert|256|ly|pc|abbr=off|lk=on}} from Earth.<ref name=aaa474_2_653/> {{As of|2011}}, one [[extrasolar planet]] has been confirmed to be orbiting the star.

This star has a [[stellar classification]] of K2&nbsp;III,<ref name=aaa480_1_91/> indicating that, at an estimated age of around four billion years,<ref name=aaa480_1_91/> it is an [[stellar evolution|evolved star]] that has reached the [[giant star|giant]] stage. It has a mass about 1.2 times larger [[solar mass|than the Sun]], but has expanded to 18 times the Sun's girth.<ref name=aaa472_2_649/> The [[effective temperature]] of the star's [[stellar atmosphere|outer atmosphere]] is 4,415&nbsp;{{val|4415|fmt=commas|ul=K}}.<ref name=aaa472_2_649/> This heat gives it the cool, orange-hued glow of a [[K-type star]].<ref name=csiro/>

Pi²² Ursae Majoris is a member of the [[Milky Way]] galaxy's [[thin disk population]]. It is following an orbit through the galaxy with an [[Orbital eccentricity|eccentricity]] of 0.10, which carries it as close to the [[Galactic Center]] as {{Convertconvert|27.7|kly|kpc|abbr=onoff}} and as far as {{Convertcvt|34.1|kly|kpc|abbr=on}}. The inclination of this orbit lies close to the [[galactic plane]], so it departs this plane by no more than {{cvt|260|ly|pc}}.<ref name=aaa480_1_91/>

Based upon observed [[radial velocity]] changes in the star, in 2007 the presence of a planetary companion was announced. The planet, designated [[4 Ursae Majoris b]], is at least seven times more massive than [[Jupiter]]. Its orbit is [[eccentricity (orbit)|eccentric]], orbiting 4 Ursae Majoris at 87% the distance from [[Sun]] to [[Earth]]. Compared to the Sun, this star has a lower abundance of elements other than hydrogen and helium, what astronomers term the star's [[metallicity]]. This is curious, because most [[main -sequence star]]s with planets tend to have a higher abundance of metals.<ref name=aaa472_2_649/>

| exoplanet = [[4 Ursae Majoris b|b]]

With [[Pi1 Ursae Majoris|π¹]], [[Sigma2Sigma1 Ursae Majoris|σ¹]], [[Sigma1Sigma2 Ursae Majoris|σ²]], [[Rho Ursae Majoris|ρ]], [[2 Ursae Majoris|A]] and [[24 Ursae Majoris|d]], it composed the Arabic [[Asterism (astronomy)|asterism]] '''Al Ṭhibā᾽''', the Gazelle.<ref name="allen1899"/>. According to the catalogue of stars in the ''Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars'', ''Al Ṭhibā'' were the title for seven stars : [[2 Ursae Majoris|A]] as ''Althiba I'', [[Pi1 Ursae Majoris|π¹]] as ''Althiba II'', this star (π²) as ''Althiba III'', [[Rho Ursae Majoris|ρ]] as ''Althiba IV'', [[Sigma2 Ursae Majoris|σ¹]] as ''Althiba V'', [[Sigma1 Ursae Majoris|σ²]] as ''Althiba VI'', and [[24 Ursae Majoris|d]] as ''Althiba VII''.<ref name=rhoads1971/>.

<ref name=aaa474_2_653>{{citation | last1=van Leeuwen | first1=F. | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | doi=10.1051/0004-6361:20078357 | bibcode=2007A&A...474..653V | arxiv=0708.1752 |date=November 2007| s2cid=18759600 }}</ref>

<ref name=aaa480_1_91>{{citation | 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 | year=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=aaa430_165>{{citation | display-authors=1 | last1=Famaey | first1=B. | last2=Jorissen | first2=A. | last3=Luri | first3=X. | last4=Mayor | first4=M. | last5=Udry | first5=S. | last6=Dejonghe | first6=H. | last7=Turon | first7=C. | title=Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters | journal=Astronomy and Astrophysics | volume=430 | pages=165–186 | doi=10.1051/0004-6361:20041272 | bibcode=2005A&A...430..165F |arxiv = astro-ph/0409579 |date=January 2005| s2cid=17804304 }}</ref>

<ref name=mnras172_667>{{citation | last1=Jennens | first1=P. A. | last2=Helfer | first2=H. L. | title=A new photometric metal abundance and luminosity calibration for field G and K giants. | journal=[[Monthly Notices of the Royal Astronomical Society]] | volume=172 | issue=3 | pages=667–679 | bibcode=1975MNRAS.172..667J |date=September 1975 | doi=10.1093/mnras/172.3.667| doi-access=free }}</ref>

<ref name="Baines2010">{{cite journal | title=Angular Diameters and Effective Temperatures of 25 K Giant Stars from the CHARA Array | url=http://iopscience.iop.org/article/10.1088/0004-637X/710/2/1365/meta | last1=Baines | first1=Ellyn K. | last2=Döllinger | first2=Michaela P. | last3=Cusano | first3=Felice | last4=Guenther | first4=Eike W. | last5=Hatzes | first5=Artie P. | last6=McAlister | first6=Harold A. | last7=ten Brummelaar | first7=Theo A. | last8=Turner | first8=Nils H. | last9=Sturmann | first9=Judit | last10=Sturmann | first10=Laszlo | last11=Goldfinger | first11=P. J. | last12=Farrington | first12=Christopher D. | last13=Ridgway | first13=Stephen T. | display-authors=1 | journal=Astrophysical Journal | volume=710 | issue=2 | pages=1365–1374 | year=2010 | arxiv=0912.5491 | bibcode=2010ApJ...710.1365B | doi=10.1088/0004-637X/710/2/1365 | s2cid=799107 }}</ref>

<ref name="allen1899">{{citation | title=Star-Names and Their Meanings | last=Allen | first=Richard Hinckley | authorlinkauthor-link=Richard Hinckley Allen | date=1899 | publisher=G. E. Stechert | publication-placelocation=New York | page=444 }}</ref>

* {{cite webencyclopedia |url=http://exoplanet.eu/star.php?st=4+Uma |title=Notes for star 4 Uma |author=Jean Schneider |year=2011 |workaccess-date=3 October 2011 |publisherarchive-date=10 February 2012 |archive-url=https://web.archive.org/web/20120210042059/http://exoplanet.eu/star.php?st=4+Uma |encyclopedia=[[Extrasolar Planets Encyclopaedia]] |accessdateurl-status=3dead October 2011}}

[[Category:HRBright Star Catalogue objects|3403]]

[[Category:Ursa Major (constellation)]]

[[Category:Stars with proper names|MuscidaAlthiba III]]