Star in the constellation Ursa Minor
RR Ursae Minoris Observation dataEpoch J2000 Equinox J2000 Constellation Ursa Minor Right ascension 14h 57m 35.00959s [ 2] Declination +65° 55′ 56.8146″[ 2] Apparent magnitude (V)4.44 - 4.85[ 3] Characteristics Spectral type M5 III[ 4] B−Vcolor index ± 0.017[ 5] Variable type SRb [ 6] Astrometry Radial velocity (Rv )± 0.30[ 7] km/s Proper motion (μ)RA: mas /yr [ 8] Dec.: +32.5mas /yr [ 8] Parallax (π)7.1± 0.37 mas [ 8] Distance 460 ± 20 ly pc ) Absolute magnitude (MV )−1.11[ 5] Orbit [ 9] Period (P)748.9 d Eccentricity (e)± 0.05Inclination (i)± 2.4[ 10] Longitude of the node (Ω)± 2.5[ 10] Periastron epoch (T)± 46 JDArgument of periastron (ω)± 22Semi-amplitude 1 )± 0.3Details Mass ± 0.1[ 11] M ☉ Radius +5.4 [ 12] R ☉ Luminosity ± 172[ 12] L ☉ Surface gravity (log g )0.00[ 13] cgs Temperature ± 37[ 12] K Other designations AAVSO 1456+66,Tau Ursae Minoris (τ UMi) [ 14] RR UMi ,BD +66°878FK5 554HD 132813HIP 73199HR 5589SAO 16558[ 2] Database references SIMBAD data
RR Ursae Minoris , abbreviatedRR UMi , is abinary star [ 13] circumpolar constellation ofUrsa Minor . It can be viewed with thenaked eye , typically having anapparent visual magnitude of around 4.710.[ 10] parallax shift ofmas [ 8] light years away. The system is moving further from the Sun with a heliocentricradial velocity of +6 km/s.[ 7]
This star was found to have a variable radial velocity byJ. H. Moore in 1910. It is a single-linedspectroscopic binary system with anorbital period of 2.05 years and aneccentricity (ovalness) of 0.13. Thea sini value is 84 Gm (0.56 AU ),[ 9] a is thesemimajor axis andi is theorbital inclination to the line of sight from the Earth. This gives a lower bound on the physical size of the orbit. The system is a source forX-ray andfar-UV emission, with the latter most likely coming from the companion.[ 13]
The visible component is an agingred giant star on theasymptotic giant branch [ 13] stellar classification of M4.5 III.[ 4] variable star byJ. Ashbrook in 1946,[ 15] semiregular variable of subtype SRb[ 6] [ 3] [ 16] [ 11] mass of the Sun and has expanded to 110 times theSun's radius . It is radiating 1,580 times theluminosity of the Sun from its enlargedphotosphere at aneffective temperature of 3,410 K.[ 12]
^ "Hipparcos Tools Interactive Data Access" .Hipparcos . ESA. Retrieved8 December 2021 .^a b c "RR UMi" .SIMBAD Centre de données astronomiques de Strasbourg . RetrievedSeptember 7, 2018 .^a b Otero, Sebastian Alberto (16 November 2009)."RR Ursae Minoris" .AAVSO Website .American Association of Variable Star Observers . Retrieved18 May 2014 . ^a b Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars".Astrophysical Journal Supplement Series .71 : 245.Bibcode :1989ApJS...71..245K .doi :10.1086/191373 .S2CID 123149047 . ^a b Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation".Astronomy Letters .38 (5): 331.arXiv :1108.4971 Bibcode :2012AstL...38..331A .doi :10.1134/S1063773712050015 .S2CID 119257644 . ^a b Samus', N. N; Kazarovets, E. V; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N (2017). "General catalogue of variable stars: Version GCVS 5.1".Astronomy Reports .61 (1): 80.Bibcode :2017ARep...61...80S .doi :10.1134/S1063772917010085 .S2CID 125853869 . ^a b de Bruijne, J. H. J.; Eilers, A.-C. (October 2012). "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project".Astronomy & Astrophysics .546 : 14.arXiv :1208.3048 Bibcode :2012A&A...546A..61D .doi :10.1051/0004-6361/201219219 .S2CID 59451347 . A61. ^a b c van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction",Astronomy and Astrophysics ,474 (2):653– 664,arXiv :0708.1752 Bibcode :2007A&A...474..653V ,doi :10.1051/0004-6361:20078357 ,S2CID 18759600 RR UMi's database entry atVizieR .^a b Batten, A. H.; Fletcher, J. M. (July 1986)."A revised spectroscopic orbit for RR Ursae Minoris" .Publications of the Astronomical Society of the Pacific .98 :647– 650.Bibcode :1986PASP...98..647B .doi :10.1086/131808 ^a b c Ren, Shulin; Fu, Yanning (March 2013)."Hipparcos Photocentric Orbits of 72 Single-lined Spectroscopic Binaries" .The Astronomical Journal .145 (3): 7.Bibcode :2013AJ....145...81R .doi :10.1088/0004-6256/145/3/81 S2CID 120199240 . 81. ^a b Halabi, Ghina M.; Eid, Mounib El (2015)."Exploring masses and CNO surface abundances of red giant stars" .Monthly Notices of the Royal Astronomical Society .451 (3): 2957.arXiv :1507.01517 Bibcode :2015MNRAS.451.2957H .doi :10.1093/mnras/stv1141 S2CID 118707332 . ^a b c d Baines, Ellyn K.; Thomas Armstrong, J.; Clark, James H.; Gorney, Jim; Hutter, Donald J.; Jorgensen, Anders M.; Kyte, Casey; Mozurkewich, David; Nisley, Ishara; Sanborn, Jason; Schmitt, Henrique R.; Van Belle, Gerard T. (2021)."Angular Diameters and Fundamental Parameters of Forty-four Stars from the Navy Precision Optical Interferometer" .The Astronomical Journal .162 (5): 198.arXiv :2211.09030 Bibcode :2021AJ....162..198B .doi :10.3847/1538-3881/ac2431 ^a b c d Ortiz, Roberto; Guerrero, Martín A. (2016)."Ultraviolet emission from main-sequence companions of AGB stars" .Monthly Notices of the Royal Astronomical Society .461 (3): 3036.arXiv :1606.09086 Bibcode :2016MNRAS.461.3036O .doi :10.1093/mnras/stw1547 S2CID 118619933 . ^ "Ursa Minor - Constellation Guide" .freestarcharts.com .^ Dettmar, R. -J.; Gieseking, F. (December 1983). "The intrinsically variable spectroscopic binary RR UMi".Astronomy and Astrophysics, Supplemental Series .54 :541– 543.Bibcode :1983A&AS...54..541D . ^ Lloyd, C.; West, K. W. (May 1996). "Observations of Low-amplitude Late-Type Variables".Information Bulletin on Variable Stars .4335 : 1.Bibcode :1996IBVS.4335....1L .
