View source for Astronomy:65 Ursae Majoris

{{short description|Star system in the constellation Ursa Major}}
{{Starbox begin|name=65 Ursae Majoris}}
{{Starbox image
 | image=
{{Location mark
|image=Ursa Major constellation map.svg|alt=|float=center|width=280
|label=|position=right
|mark=Red circle.svg|mark_width=8|mark_link=65 UMa
|x=420|y=623
}}
|caption=Location of 65 Ursae Majoris (circled)
}}
{{Starbox observe 2s
|epoch=[[Astronomy:J2000|J2000]]
|constell=[[Astronomy:Ursa Major|Ursa Major]]
|component1=65 UMa ABC
|ra1={{RA|11|55|05.74925}}<ref name=HIP>{{cite journal|title=Validation of the new Hipparcos reduction|url=http://www.aanda.org/index.php?option=com_article&access=bibcode&Itemid=129&bibcode=2007A%2526A...474..653VFUL|author1=van Leeuwen, F.|display-authors=0|journal=Astronomy and Astrophysics|volume=474|issue=2|pages=653–664|date=2007|arxiv=0708.1752|bibcode=2007A&A...474..653V|doi=10.1051/0004-6361:20078357|s2cid = 18759600}}</ref>
|dec1={{DEC|+46|28|36.6408}}<ref name=HIP/>
|appmag_v1=+6.54<ref name=UBV>{{cite journal|bibcode=1964ApJ...139.1105T|title=A UBV Study of 94 Wide Visual Binaries|journal=Astrophysical Journal|volume=139|page=1105|author1=Tolbert, C. R.|year=1964|doi=10.1086/147852|doi-access=free}}</ref> {{nowrap begin}}(A/B/C = 6.7 / 8.5 / 8.32)<ref name=tokovinin>{{cite journal|bibcode=1997A&AS..124...75T|title=MSC - a catalogue of physical multiple stars|journal=Astronomy & Astrophysics Supplement Series|volume=124|pages=75–84|last1=Tokovinin|first1=A. A.|year=1997|doi=10.1051/aas:1997181|doi-access=free}}</ref>{{nowrap end}}
|component2=65 UMa D
|ra2={{RA|11|55|11.33152}}<ref name=HIP/>
|dec2={{DEC|+46|28|11.2150}}<ref name=HIP/>
|appmag_v2=+6.965<ref name=TYC2>{{cite journal|title=The Tycho-2 catalogue of the 2.5 million brightest stars|author1=Høg, E.|display-authors=0|date=2000|journal=Astronomy and Astrophysics|volume=355|pages=L27–L30|bibcode=2000A&A...355L..27H}}</ref>
}}
{{Starbox character
|component1=65 UMa ABC
|class=A7 / A7 / A3 / ? / ?<ref name=Zasche/>
|b-v=+0.11<ref name=UBV/>
|u-b=+0.08<ref name=UBV/>
|variable=[[Astronomy:Algol variable|Algol]]<ref name=Zasche/>
|component2=65 UMa D
|class2=A0p<ref name=Pandey>{{cite journal|title=Abundance and stratification analysis of the CP star HD 103498|author1=Pandey, Chhavi P.|author2=Shulyak, Denis V.|author3=Ryabchikova, Tanya|author4=Kochukhov, Oleg|date=2012|journal=Astronomical Society of India Conference Series|volume=6|page=225|doi=10.1111/j.1365-2966.2011.19281.x|bibcode=2012ASInC...6..225P|arxiv=1106.3727|s2cid=56288919}}</ref>
|b-v2=+0.02<ref name=UBV/>
|u-b2=+0.01<ref name=UBV/>
}}
{{Starbox astrometry
|component1=65 UMa ABC
|radial_v={{val|-3.90|4.4}}<ref name=RV>{{cite journal|title=Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system|author=Gontcharov, G. A.|date=2006|journal=Astronomy Letters|volume=32|issue=11|pages=759–771|bibcode=2006AstL...32..759G|doi=10.1134/S1063773706110065|arxiv=1606.08053|s2cid=119231169}}</ref>
|prop_mo_ra=10.41<ref name=HIP/>
|prop_mo_dec=2.38<ref name=HIP/>
|parallax=4.72
|p_error=0.58
|parallax_footnote=<ref name=HIP/>
|absmag_v=−0.05<ref name=xhip>{{cite journal
 | title=XHIP: An extended hipparcos compilation
 | last1=Anderson | first1=E. | last2=Francis | first2=Ch.
 | journal=Astronomy Letters
 | volume=38 | issue=5 | pages=331 | year=2012
 | bibcode=2012AstL...38..331A | arxiv=1108.4971
 | doi=10.1134/S1063773712050015 | s2cid=119257644 }}</ref>
|component2=65 UMa D
|radial_v2={{val|-7.00|3.7}}<ref>{{cite journal|title=Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations|author1=Kharchenko, N. V.|display-authors=0|journal=Astronomische Nachrichten|volume=328|issue=9|page=889|date=2007|bibcode=2007AN....328..889K|doi=10.1002/asna.200710776|arxiv=0705.0878|s2cid=119323941}}</ref>
|prop_mo_ra2=11.82<ref name=HIP/>
|prop_mo_dec2=0.39<ref name=HIP/>
|parallax2=3.37
|p_error2=0.56
|parallax_footnote2=<ref name=HIP/>
|absmag_v2=−0.1<ref name=gomez1999>{{cite journal
 | bibcode=1998A&A...336..953G
| title=The HR-diagram from HIPPARCOS data. Absolute magnitudes and kinematics of BP - AP stars
| journal=Astronomy and Astrophysics
| volume=336
| pages=953
| last1=Gomez
| first1=A. E.
| last2=Luri
| first2=X.
| last3=Grenier
| first3=S.
| last4=Figueras
| first4=F.
| last5=North
| first5=P.
| last6=Royer
| first6=F.
| last7=Torra
| first7=J.
| last8=Mennessier
| first8=M. O.
| year=1998
}}</ref>
}}
{{Starbox orbit
|reference=<ref name=Zasche>{{cite journal|title=Unique sextuple system: 65 Ursae Majoris|author1=Zasche, P.|author2=Uhlář, R.|author3=Šlechta, M.|author4=Wolf, M.|author5=Harmanec, P.|author6=Nemravová, J. A.|author7=Korčáková, D.|journal=Astronomy & Astrophysics|volume=542|pages=A78|date=2012|bibcode=2012A&A...542A..78Z|doi=10.1051/0004-6361/201219134|arxiv=1207.0651|s2cid=56328797}}</ref>
|primary=65 UMa Aa1
|name=65 UMa Aa2
|period_unitless={{val|1.73043|u=days}}
|axis_unitless=
|periastron=
|node=
|periarg=
|inclination={{val|86.5|0.2}}
|eccentricity=
|k1={{val|133.3|4.2}}
|k2={{val|135.7|4.2}}
}}
{{Starbox orbit
|reference=<ref name=Zasche/>
|primary=65 UMa Aa
|name=65 UMa Ab
|period_unitless={{val|641.5|16.7}}
|axis_unitless=
|periastron=
|node=
|periarg=
|inclination=47
|eccentricity={{val|0.169|0.048}}
|k1=13.7<ref name=tokovinin/>
|k2={{val|19.9|2.7}}
}}
{{Starbox orbit
|reference=<ref name=Zasche/>
|primary=65 UMa A
|name=65 UMa B
|period={{val|118.209|0.690}}
|axis_unitless={{val|208.2|9.7|ul=mas}}
|periastron={{val|2447516.9|126.8}}
|node={{val|92.1|4.2}}
|periarg={{val|202.7|1.3}}
|inclination={{val|38.1|2.4}}
|eccentricity={{val|0.504|0.006}}
}}
{{Starbox detail
|component1=65 UMa Aa1
|mass={{val|1.74|0.06}}<ref name=Zasche/>
|temperature=8,000<ref name=Zasche/>
|radius={{val|1.86|0.08}}<ref name=Zasche/>
|component2=65 UMa Aa2
|mass2={{val|1.71|0.06}}<ref name=Zasche/>
|temperature2={{val|7948|20|fmt=commas}}<ref name=Zasche/>
|radius2={{val|1.81|0.08}}<ref name=Zasche/>
}}
{{Starbox detail|no_heading=y
|component1=65 UMa Ab
|mass={{val|2.4|0.4}}<ref name=Zasche/>
}}
{{Starbox detail|no_heading=y
|component1=65 UMa B
|mass={{val|2.4|2.0}}<ref name=Zasche/>
}}
{{Starbox detail|no_heading=y
|component1=65 UMa C
|mass=2.01<ref name=tokovinin/>
}}
{{Starbox detail|no_heading=y
|component1=65 UMa D
|mass=2.31<ref name=yu2019>{{cite journal |bibcode=2019AstBu..74...66G |title=On Properties of Main Sequence Magnetic Stars |last1=Glagolevskij |first1=Yu. V. |journal=Astrophysical Bulletin |year=2019 |volume=74 |issue=1 |page=66 |doi=10.1134/S1990341319010073 |s2cid=149900274 }}</ref>{{nowrap|(3.02 + 1.64<ref name=tokovinin/>)}}
|radius=2.93<ref name=yu2019/>
|temperature=8,600<ref name=yu2019/>
|luminosity=79<ref name=yu2019/>
|gravity=3.85<ref name=yu2019/>
|age_myr=525<ref name=yu2019/>
}}
{{Starbox catalog
|names=[[Astronomy:Flamsteed designation|65]]&nbsp;UMa, ADS&nbsp;8347, CCDM&nbsp;J11551+4629
|component1=65 UMa ABC
|names1=[[Astronomy:Variable star designation|DN]]&nbsp;UMa, BD+47°1913, HD&nbsp;103483, HIP&nbsp;58112, [[Astronomy:Bright Star Catalogue|HR]]&nbsp;4560, [[Astronomy:Smithsonian Astrophysical Observatory Star Catalog|SAO]]&nbsp;43945
|component2=65 UMa D
|names2=BD+47°1914, HD&nbsp;103498, HIP&nbsp;58117, [[Astronomy:Bright Star Catalogue|HR]]&nbsp;4561, [[Astronomy:Smithsonian Astrophysical Observatory Star Catalog|SAO]]&nbsp;43946
}}
{{Starbox reference
|Simbad2=DN+UMa|sn2=65 UMa AB
|Simbad3=ADS+8347+C|sn3=65 UMa C
|Simbad4=HR+4561|sn4=65 UMa D
}}
{{Starbox end}}
'''65 Ursae Majoris''', abbreviated as '''65 UMa''', is a [[Astronomy:Star system|star system]] in the [[Astronomy:Constellation|constellation]] of [[Astronomy:Ursa Major|Ursa Major]]. With a combined [[Astronomy:Apparent magnitude|apparent magnitude]] of about 6.5,<ref name=UBV/> it is at the [[Astronomy:Bortle scale|limit of human eyesight]] and is just barely visible to the naked eye in ideal conditions. It is about 760 [[Light year|light year]]s away from Earth.

65 Ursae Majoris is a sextuple star system. It contains six stars in a hierarchical orbit where each star [[Physics:Orbit|orbit]]s its inner stars. Such systems are uncommon, with only a few sextuple stars known.<ref name=Zasche/> Higher-multiplicity star systems are uncommon because they are less stable than their simpler counterparts, and often decay into smaller systems.

==Multiplicity==
<div style="float:left; width:260px; border:solid black 1px; text-align: center; margin: 8px; padding: 4px; font-size: 90%;">
{{chart/start}}
{{chart|border=1| | |  |  |  |, |S1|S1='''Aa1''' }}
{{chart|border=0| | |  |  |, |( |PA|PA=Period&nbsp;=&nbsp;1.73d<br/>a&nbsp;=&nbsp;0.2&nbsp;mas }}
{{chart|border=1| | |  |, |( |` |S2|S2='''Aa2''' }}
{{chart|border=0| | |  |! |! |PB|  |PB=Period = 641d<br/>a&nbsp;=&nbsp;11&nbsp;mas }}
{{chart|border=1| | |, |( |` |S3|  |S3='''Ab''' }}
{{chart|border=0| | |! |! |PC|  |  |PC=Period = 118y<br/>a&nbsp;=&nbsp;0.18″ }}
{{chart|border=1| |,|( |` |S4|  |  |S4='''B''' }}
{{chart|border=0| |!|! |PD|  |  |  |PD=3.4″&nbsp;separation }}
{{chart|border=1| |(|` |S5|  |  |  |S5='''C''' }}
{{chart|border=0| |!|PE|  |  |  |  |PE=63″&nbsp;separation }}
{{chart|border=1| |`|S6|  |  |  |  |S6='''D''' }}
{{chart/end}}
Hierarchy of orbits in the 65 Ursae Majoris system
</div>
The central pair of stars, 65 Ursae Majoris Aa1 and Aa2, are both A-type main-sequence stars. These are relatively bright, white-colored stars that typically have masses from {{solar mass|1.6|link=yes}} to {{solar mass|2.4}}.<ref>{{cite journal|title=The physical properties of normal A stars|author=Adelman, Saul J.|journal=Proceedings of the International Astronomical Union|volume=2004|pages=1–11|date=2004|bibcode=2004IAUS..224....1A|doi=10.1017/S1743921304004314|doi-access=free}}</ref> They have relatively low masses for A-type main sequence stars and have spectral types of A7V.<ref name=Zasche/> Its [[Astronomy:Orbital period|orbital period]] is 1.73 days.<ref name=Zasche/>

The innermost binary pair 65 Ursae Majoris Aa is orbited by another star, designated 65 Ursae Majoris Ab. It is a [[Astronomy:Spectroscopic binary|spectroscopic binary]]: while the pair cannot be [[Angular resolution|resolved]], periodic Doppler shifts in their [[Spectrum|spectra]] indicate that there must be orbital motion. 65 Ursae Majoris Ab orbits the inner pair with a period of 641 days (1.76 years) and an [[Astronomy:Orbital eccentricity|eccentricity]] of 0.169.<ref name=Zasche/>

65 Ursae Majoris B orbits the three inner stars every 118 years. It is separated from the triple by {{val|0.18|ul=″}}, and an [[Astronomy:Astrometric binary|astrometric]] orbit has been calculated. 65 Ursae Majoris C and D are common [[Astronomy:Proper motion|proper motion]] companions and are separated {{val|4|u=″}} and {{val|63|u=″}} respectively from the central system.<ref name=Zasche/> 65 Ursae Majoris D also appears to be a [[Chemistry:Chemically peculiar star|chemically peculiar star]] with higher amounts of [[Chemistry:Chromium|chromium]], [[Chemistry:Strontium|strontium]], and [[Chemistry:Europium|europium]] than normal.<ref name=Abt>{{cite journal|title=The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars|author1=Abt, Helmut A.|author2=Morrell, Nidia I.|journal=Astrophysical Journal Supplement|volume=95|page=135|date=1995|bibcode=1995ApJS...99..135A|doi=10.1086/192182|doi-access=free}}</ref> Because of its unusual composition, determination of its stellar parameters is difficult; the [[Astronomy:Effective temperature|effective temperature]] of this star may be 9,300 or {{val|9500|ul=K|fmt=commas}}, with the radius and the [[Physics:Surface gravity|surface gravity]] determined for the star dependent on the effective temperature.<ref name=Pandey/>  [[Physics:Speckle interferometry|Speckle interferometry]] results have resolved 65 Ursae Majoris D into two components separated by {{val|138|ul=mas}} but this has not been confirmed by other observers.  The two stars resolved differ in brightness by about two magnitudes.<ref name=balega2012>{{cite journal |bibcode=2012AstBu..67...44B |title=Speckle interferometry of magnetic stars with the BTA. I. First results |last1=Balega |first1=Yu. Yu |last2=Dyachenko |first2=V. V. |last3=Maksimov |first3=A. F. |last4=Malogolovets |first4=E. V. |last5=Rastegaev |first5=D. A. |last6=Romanyuk |first6=I. I. |journal=Astrophysical Bulletin |year=2012 |volume=67 |issue=1 |page=44 |doi=10.1134/S199034131201004X |s2cid=122554107 }}</ref>  An orbit for two stars has been estimated to have a period of about 79 years.<ref name=tokovinin/>
{{clear left}}

==Variability==
[[File:DNUMaLightCurve.png|thumb|left|A [[Astronomy:Light curve|light curve]] for DN Ursae Majoris, plotted from ''TESS'' data<ref name=MAST/>]]
65 Ursae Majoris A is a [[Astronomy:Variable star|variable star]] with the [[Astronomy:Variable star designation|variable star designation]] '''DN Ursae Majoris'''.  The pair Aa1 and Aa2 form an [[Astronomy:Eclipsing binary|eclipsing binary]] as they periodically pass in front of each other while orbiting.  The primary and secondary eclipses are almost identical and the [[Astronomy:Apparent magnitude|apparent magnitude]] of the system varies between 6.55 and 6.65 twice during each orbit of 1.73 days.<ref name=GCVS>{{cite journal|bibcode=2009yCat....102025S|title=VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)|journal=VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S|volume=1|display-authors=0|author1=Samus, N. N.|author2=Durlevich, O. V.|year=2009}}</ref>  The brightness variation is very small because the non-eclipsing component Ab is the brightest of the three stars and contributes 80% of the visible light.<ref name=Zasche/>

==Distance==
[[Astronomy:Stellar parallax|Trigonometric parallax]] measurements made by the [[Astronomy:Hipparcos|Hipparcos]] [[Engineering:Spacecraft|spacecraft]] put the 65 Ursae Majoris ABC system at a distance of about 690 [[Light year|light year]]s (210 [[Astronomy:Parsec|parsec]]s), and component D at about 1,000 [[Light year|light year]]s (300 [[Astronomy:Parsec|parsec]]s).<ref name=HIP/>  The [[Astronomy:Dynamical parallax|dynamical parallax]] determined from the calculated orbits of the stars gives a distance of {{convert|234|+/-|29|pc|ly|order=flip}}.<ref name=Zasche/>  [[Engineering:Gaia (spacecraft)|Gaia]] has published measurements for the AB system and for component D, but they are both highly uncertain.  Gaia Early Data Release 3 includes a somewhat more reliable measurement for the parallax of component C at {{val|4.3897|0.0245|ul=mas}},<ref name=edr3c>{{cite Gaia EDR3|774274748251116672}}</ref> implying a distance of about 740 light years.<ref name=bailer-jones>{{cite journal |bibcode=2021AJ....161..147B |title=Estimating Distances from Parallaxes. V. Geometric and Photogeometric Distances to 1.47 Billion Stars in Gaia Early Data Release 3 |last1=Bailer-Jones |first1=C. A. L. |last2=Rybizki |first2=J. |last3=Fouesneau |first3=M. |last4=Demleitner |first4=M. |last5=Andrae |first5=R. |journal=The Astronomical Journal |year=2021 |volume=161 |issue=3 |page=147 |doi=10.3847/1538-3881/abd806 |arxiv=2012.05220 |s2cid=228063812 |doi-access=free }}</ref>
{{clear left}}

==See also==
*[[Astronomy:Castor (star)|Castor]], another multiple star system with six stars
*[[Astronomy:Zeta Phoenicis|Zeta Phoenicis]], a multiple star system including an eclipsing binary

==References==
{{reflist|refs=

<ref name=MAST>{{cite web |title=MAST: Barbara A. Mikulski Archive for Space Telescopes |url=https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html |publisher=Space Telescope Science Institute |access-date=8 December 2021}}</ref>

}}

{{Sky|11|55|05.75|+|46|28|37|763}}

{{Stars of Ursa Major}}

[[Category:Spectroscopic binaries]]
[[Category:Algol variables]]
[[Category:Multiple star systems|6]]
[[Category:Hipparcos objects|058112]]
[[Category:Henry Draper Catalogue objects|103483]]
[[Category:Bright Star Catalogue objects|4560]]
[[Category:Durchmusterung objects]]
[[Category:Objects with variable star designations|Ursae Majoris, DN]]
[[Category:Flamsteed objects|Ursae Majoris, 65]]
[[Category:A-type main-sequence stars]]

{{Sourceattribution|65 Ursae Majoris}}