Binary star system in the constellation Ursa Major
78 Ursae Majoris is abinary star system in the northerncircumpolar constellation ofUrsa Major. It is visible to the naked eye as a faint point of light with a combinedapparent visual magnitude of 4.93.[13]Parallax estimates byHipparcos put it at a distance of 83 light-years (25 pc),[1] but it is drifting closer with aradial velocity of −5 km/s.[2] The system is a candidate member of theUrsa Major Moving Group.[14]
The binary nature of this system was announced byS. W. Burnham in 1894.[15] The pair orbit each other with aperiod of 105 years and aneccentricity of 0.39. Theirsemimajor axis has anangular size of1.2″ and theorbital plane isinclined by 47°.[8]
The primary member, designated component A, has a magnitude of 5.02[3] and is anF-type main-sequence star with astellar classification of F2V.[4] It is 785[9] million years old and is spinning with aprojected rotational velocity of 92 km/s.[12] The star has 1.34[9] times themass of the Sun and is radiating 5.75[2] times theSun's luminosity from itsphotosphere at aneffective temperature of 6,908 K.[9]
The secondary, designated component B, has a visual magnitude of 7.88.[3] It is aG-type main-sequence star with a class of G6V.[5] The star is a suspectedvariable.[16]
- ^abcdefvan Leeuwen, F. (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.
- ^abcdefAnderson, 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.
- ^abcFabricius, C.; et al. (2002)."The Tycho double star catalogue".Astronomy and Astrophysics.384:180–189.Bibcode:2002A&A...384..180F.doi:10.1051/0004-6361:20011822.
- ^abGray, R. O.; et al. (2003). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I".The Astronomical Journal.126 (4): 2048.arXiv:astro-ph/0308182.Bibcode:2003AJ....126.2048G.doi:10.1086/378365.S2CID 119417105.
- ^abEdwards, T. W. (April 1976), "MK classification for visual binary components",Astronomical Journal,81:245–249,Bibcode:1976AJ.....81..245E,doi:10.1086/111879.
- ^Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)".Catalogue of Eggen's UBV Data.Bibcode:1986EgUBV........0M.
- ^Eggen, Olin J. (August 1998), "The Sirius Supercluster and Missing Mass near the Sun",The Astronomical Journal,116 (2):782–788,Bibcode:1998AJ....116..782E,doi:10.1086/300465.
- ^abDrummond, Jack D. (March 2014), "Binary Stars Observed with Adaptive Optics at the Starfire Optical Range",The Astronomical Journal,147 (3): 10,Bibcode:2014AJ....147...65D,doi:10.1088/0004-6256/147/3/65, 65.
- ^abcdefgDavid, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets",The Astrophysical Journal,804 (2): 146,arXiv:1501.03154,Bibcode:2015ApJ...804..146D,doi:10.1088/0004-637X/804/2/146,S2CID 33401607.
- ^abJustesen, A. B.; Albrecht, S. (October 2020). "The spin-orbit alignment of visual binaries".Astronomy & Astrophysics.642: 10.arXiv:2008.12068.Bibcode:2020A&A...642A.212J.doi:10.1051/0004-6361/202039138.S2CID 221340982. A212.
- ^Gáspár, András; et al. (2016), "The Correlation between Metallicity and Debris Disk Mass",The Astrophysical Journal,826 (2): 171,arXiv:1604.07403,Bibcode:2016ApJ...826..171G,doi:10.3847/0004-637X/826/2/171,S2CID 119241004.
- ^abAmmler-von Eiff, Matthias; Reiners, Ansgar (June 2012), "New measurements of rotation and differential rotation in A-F stars: are there two populations of differentially rotating stars?",Astronomy & Astrophysics,542: A116,arXiv:1204.2459,Bibcode:2012A&A...542A.116A,doi:10.1051/0004-6361/201118724,S2CID 53666672.
- ^ab"* 78 UMa".SIMBAD.Centre de données astronomiques de Strasbourg. Retrieved19 August 2017.
- ^Nakajima, Tadashi; Morino, Jun-Ichi (2012), "Potential Members of Stellar Kinematic Groups within 30 pc of the Sun",The Astronomical Journal,143 (1): 2,Bibcode:2012AJ....143....2N,doi:10.1088/0004-6256/143/1/2.
- ^"Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Archived fromthe original on 1 August 2017. Retrieved19 August 2017.
- ^Baize, P.; Petit, M. (March 1989), "Etoiles doubles orbitales à composantes variables",Astronomy and Astrophysics, Supplemental Series,77:497–511,Bibcode:1989A&AS...77..497B.
