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Lambda Ursae Majoris

From Wikipedia, the free encyclopedia
Star in the constellation Ursa Major
Lambda Ursae Majoris
Diagram showing star positions and boundaries of the Ursa Major constellation and its surroundings
Diagram showing star positions and boundaries of the Ursa Major constellation and its surroundings

Location of λ Ursae Majoris (circled)
Observation data
Epoch J2000      Equinox J2000
ConstellationUrsa Major
Right ascension10h 17m 05.78287s[1]
Declination+42° 54′ 51.6808″[1]
Apparent magnitude (V)+3.45[2]
Characteristics
Spectral typeA2 IV[3]
U−Bcolor index+0.06[2]
B−Vcolor index+0.03[2]
Astrometry
Radial velocity (Rv)+18.1[4] km/s
Proper motion (μ)RA: –180.65[1]mas/yr
Dec.: –46.07[1]mas/yr
Parallax (π)23.72±0.78 mas[1]
Distance138 ± 5 ly
(42 ± 1 pc)
Absolute magnitude (MV)+0.10[5]
Details
Mass2.11[6] M☉
Radius2.3[7] R☉
Luminosity37[7] L☉
Surface gravity (log g)3.76±0.14[6] cgs
Temperature9,247±314[6] K
Metallicity [Fe/H]+0.20[8] dex
Rotational velocity (v sin i)50[9] km/s
Age380[6] Myr
Other designations
Tania Borealis, λ Ursae Majoris, λ UMa, Lambda UMa, 33 Ursae Majoris,BD+43 2005,FK5 383,GC 14113,HD 89021,HIP 50372,HR 4033,PPM 51795,SAO 43268.[10]
Database references
SIMBADdata

Lambda Ursae Majoris (λ Ursae Majoris, abbreviatedLambda UMa,λ UMa), formally namedTania Borealis/ˈteɪniəˌbɒriˈælɪs/,[11][12] is astar in the northerncircumpolar constellation ofUrsa Major.

Properties

[edit]

This star has anapparent visual magnitude of +3.45,[2] making it one of thebrighter members of the constellation. The distance to this star has been measured directly using theparallax technique, which yields a value of roughly 138light-years (42parsecs) with a 4%margin of error. Thestellar classification of Lambda Ursae Majoris is A2 IV,[3] with theluminosity class of 'IV' indicating that, after 410 million years[13] on themain sequence, this star is in the process ofevolving into agiant star as the supply of hydrogen at its core becomes exhausted. Compared to the Sun it has 240% of the mass and 230% of the Sun's radius, but is radiating 37 times as much luminosity.[7] This energy is being emitted from the star'souter atmosphere at aneffective temperature of 9,280 K,[8] giving it the characteristic white-hot glow of anA-type star.[14]

Nomenclature

[edit]

λ Ursae Majoris (Latinised toLambda Ursae Majoris) is the star'sBayer designation.

It bore the traditional namesTania (shared withMu Ursae Majoris) andTania Borealis.Tania comes from theArabic phraseAl Fiḳrah al Thānia 'the Second Spring (of the Gazelle)'.[15] andBorealis (originallyborealis[16]) isLatin for 'the north side'. In 2016, theInternational Astronomical Union organized aWorking Group on Star Names (WGSN)[17] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[18] included a table of the first two batches of names approved by the WGSN; which includedTania Borealis for this star.

InChinese,三台 (Sān Tái), meaningThree Steps, refers to an asterism consisting of Lambda Ursae Majoris,Iota Ursae Majoris,Kappa Ursae Majoris,Mu Ursae Majoris,Nu Ursae Majoris andXi Ursae Majoris. Consequently, theChinese name for Lambda Ursae Majoris itself is中台一 (Zhōng Tái yī, English:Star of First Middle Step).[19]

References

[edit]
  1. ^abcdevan 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
  2. ^abcdJohnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars",Communications of the Lunar and Planetary Laboratory,4 (99): 99,Bibcode:1966CoLPL...4...99J
  3. ^abCowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications",Astronomical Journal,74:375–406,Bibcode:1969AJ.....74..375C,doi:10.1086/110819
  4. ^Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick (eds.),Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, vol. 30, University of Toronto:International Astronomical Union, p. 57,Bibcode:1967IAUS...30...57E
  5. ^Eggen, Olin J. (July 1998), "The Age Range of Hyades Stars",The Astronomical Journal,116 (1):284–292,Bibcode:1998AJ....116..284E,doi:10.1086/300413,S2CID 122285420.
  6. ^abcdDavid, 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.
  7. ^abcMalagnini, M. L.; Morossi, C. (November 1990), "Accurate absolute luminosities, effective temperatures, radii, masses and surface gravities for a selected sample of field stars",Astronomy and Astrophysics Supplement Series,85 (3):1015–1019,Bibcode:1990A&AS...85.1015M
  8. ^abHill, G. M. (February 1995), "Compositional differences among the A-type stars. 2: Spectrum synthesis up to V sin i = 110 km/s",Astronomy and Astrophysics,294 (2):536–546,Bibcode:1995A&A...294..536H
  9. ^Royer, F.; Zorec, J.; Gómez, A. E. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions",Astronomy and Astrophysics,463 (2):671–682,arXiv:astro-ph/0610785,Bibcode:2007A&A...463..671R,doi:10.1051/0004-6361:20065224,S2CID 18475298
  10. ^"lam UMa -- High proper-motion Star",SIMBAD,Centre de Données astronomiques de Strasbourg, retrieved2012-01-20
  11. ^Kunitzsch, Paul; Smart, Tim (2006).A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub.ISBN 978-1-931559-44-7.
  12. ^"IAU Catalog of Star Names". Retrieved28 July 2016.
  13. ^Su, K. Y. L.; et al. (December 2006), "Debris Disk Evolution around A Stars",The Astrophysical Journal,653 (1):675–689,arXiv:astro-ph/0608563,Bibcode:2006ApJ...653..675S,doi:10.1086/508649,S2CID 14116473
  14. ^"The Colour of Stars",Australia Telescope, Outreach and Education,Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived fromthe original on March 18, 2012, retrieved2012-01-16
  15. ^Richard Hinckley Allen :Star Names — Their Lore and Meaning - Ursa Major, the Greater Bear
  16. ^Piazzi, G.,The Palermo Catalogue, Palermo, 1814.
  17. ^"IAU Working Group on Star Names (WGSN)". Retrieved22 May 2016.
  18. ^"Bulletin of the IAU Working Group on Star Names, No. 1"(PDF). Retrieved28 July 2016.
  19. ^(in Chinese)(Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 21 日Archived 2016-03-03 at theWayback Machine
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