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Zeta Ursae Minoris

January 01, 1970

Zeta Ursae Minoris, which is Latinized from ζ Ursae Minoris, is a single[12] star in the northern circumpolar constellation of Ursa Minor, forming the northernmost part of the bowl in this "little dipper" asterism.[13] The star has a white hue and is faintly visible to the naked eye with an apparent visual magnitude of +4.28. It is located at a distance of approximately 369 light-years from the Sun based on parallax,[1] but is drifting further closer with a radial velocity of about –13 km/s.[6]

ζ Ursae Minoris
Location of ζ Ursae Minoris (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Minor
Right ascension 15h 44m 03.51892s[1]
Declination +77° 47′ 40.1788″[1]
Apparent magnitude (V) +4.29[2]
Characteristics
Spectral type A3Vn[3]
U−B color index +0.05[4]
B−V color index 0.038±0.005[2]
Variable type Suspected δ Sct[5]
Astrometry
Radial velocity (Rv)−13.1±4.1[6] km/s
Proper motion (μ) RA: 19.91[1] mas/yr
Dec.: −1.99[1] mas/yr
Parallax (π)8.84 ± 0.12 mas[1]
Distance369 ± 5 ly
(113 ± 2 pc)
Absolute magnitude (MV)−0.98[2]
Details
Mass~3.4[7] M☉
Radius6.15[8] R☉
Luminosity227[2] L☉
Temperature8,720[8] K
Rotational velocity (v sin i)210[9] km/s
Age180[10] Myr
Other designations
Zeta UMi, ζ UMi, 16 Ursae Minoris, NSV 7263, BD+78°527, FK5 590, GC 21243, HD 142105, HIP 77055, HR 5903, SAO 8328[11]
Database references
SIMBADdata
A light curve for Zeta Ursae Minoris, plotted from TESS data. The main plot shows the flux as a function of time, and the inset plot shows the same data (excluding the eclipse) folded with the pulsation period.[14]

The stellar classification of Zeta UMi is A3Vn,[3] a notation that indicates this is an A-type main-sequence star with broad "nebulous" absorption lines in its spectrum due to rapid rotation. Based on photometric data, some light variability was suspected by R. A. Baker in 1926, and it may be a Delta Scuti variable.[5] It is a pulsating variable star, with a period of 15.8 hours, and it also undergoes eclipses.[14] The star is spinning with a projected rotational velocity of 210 km/s, which is creating an equatorial bulge that is estimated to be 10% larger than the polar radius.[9]

Zeta Ursae Minoris is about 180[10] million years old with 6.15[8] times the radius of the Sun. It is radiating 227[2] times the luminosity of the Sun from its photosphere at an effective temperature of 8,720 K.[8] This anomalously high temperature and an absolute magnitude of –0.98[2] may indicate it is on the verge of evolving into a giant star.[7] An infrared excess has been detected from an orbiting circumstellar disk.[10] A black body fit to the data yields a mean dust temperature of 160 K and an orbital radius of 42.5 AU.[8]

In some Arabic star charts it is listed as أخفى الفرقدين ʼakhfā al-farqadayn, meaning "the dimmer of the two calves", and paired with η Ursae Minoris as ʼanwar al-farqadayn, "the brighter of the two calves". The names may originally refer to a pair of Ibexes, and are more properly applied to γ UMi and β UMi, respectively, the brighter two stars in the rectangle of Ursa Minor.[15]

References edit

  1. ^ a b c d e f van 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.
  2. ^ a b c d e f 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.
  3. ^ a b Cowley, 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. ^ Johnson, 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.
  5. ^ a b Frolov, M. S. (April 1970). "List of Probable Delta Scuti Stars". Information Bulletin on Variable Stars. 427: 1. Bibcode:1970IBVS..427....1F.
  6. ^ a b Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
  7. ^ a b Kaler, James B. "Alifa al Farkadain". Stars. University of Illinois. Retrieved 21 June 2014.
  8. ^ a b c d e Cotten, Tara H.; Song, Inseok (July 2016). "A Comprehensive Census of Nearby Infrared Excess Stars". The Astrophysical Journal Supplement Series. 225 (1): 24. arXiv:1606.01134. Bibcode:2016ApJS..225...15C. doi:10.3847/0067-0049/225/1/15. S2CID 118438871. 15.
  9. ^ a b van Belle, Gerard T. (March 2012). "Interferometric observations of rapidly rotating stars". The Astronomy and Astrophysics Review. 20 (1): 51. arXiv:1204.2572. Bibcode:2012A&ARv..20...51V. doi:10.1007/s00159-012-0051-2. S2CID 119273474.
  10. ^ a b c 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.
  11. ^ "zet UMi". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-01-08.
  12. ^ Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
  13. ^ Harrington, Philip S. (October 21, 2010). Cosmic Challenge: The Ultimate Observing List for Amateurs. Cambridge University Press. p. 38. ISBN 9781139493680.
  14. ^ a b "zet UMi". The International Variable Star Index. AAVSO. Retrieved 16 October 2022.
  15. ^ Allen, Richard Hinckley (1899). Star-names and Their Meanings. G. E. Stechert. pp. 447–460.

January 01, 1970
zeta, ursae, minoris, which, latinized, from, ursae, minoris, single, star, northern, circumpolar, constellation, ursa, minor, forming, northernmost, part, bowl, this, little, dipper, asterism, star, white, faintly, visible, naked, with, apparent, visual, magn. Zeta Ursae Minoris which is Latinized from z Ursae Minoris is a single 12 star in the northern circumpolar constellation of Ursa Minor forming the northernmost part of the bowl in this little dipper asterism 13 The star has a white hue and is faintly visible to the naked eye with an apparent visual magnitude of 4 28 It is located at a distance of approximately 369 light years from the Sun based on parallax 1 but is drifting further closer with a radial velocity of about 13 km s 6 z Ursae MinorisLocation of z Ursae Minoris circled Observation dataEpoch J2000 Equinox J2000 Constellation Ursa Minor Right ascension 15h 44m 03 51892s 1 Declination 77 47 40 1788 1 Apparent magnitude V 4 29 2 Characteristics Spectral type A3Vn 3 U B color index 0 05 4 B V color index 0 038 0 005 2 Variable type Suspected d Sct 5 AstrometryRadial velocity Rv 13 1 4 1 6 km sProper motion m RA 19 91 1 mas yr Dec 1 99 1 mas yrParallax p 8 84 0 12 mas 1 Distance369 5 ly 113 2 pc Absolute magnitude MV 0 98 2 DetailsMass 3 4 7 M Radius6 15 8 R Luminosity227 2 L Temperature8 720 8 KRotational velocity v sin i 210 9 km sAge180 10 Myr Other designationsZeta UMi z UMi 16 Ursae Minoris NSV 7263 BD 78 527 FK5 590 GC 21243 HD 142105 HIP 77055 HR 5903 SAO 8328 11 Database referencesSIMBADdata A light curve for Zeta Ursae Minoris plotted from TESS data The main plot shows the flux as a function of time and the inset plot shows the same data excluding the eclipse folded with the pulsation period 14 The stellar classification of Zeta UMi is A3Vn 3 a notation that indicates this is an A type main sequence star with broad nebulous absorption lines in its spectrum due to rapid rotation Based on photometric data some light variability was suspected by R A Baker in 1926 and it may be a Delta Scuti variable 5 It is a pulsating variable star with a period of 15 8 hours and it also undergoes eclipses 14 The star is spinning with a projected rotational velocity of 210 km s which is creating an equatorial bulge that is estimated to be 10 larger than the polar radius 9 Zeta Ursae Minoris is about 180 10 million years old with 6 15 8 times the radius of the Sun It is radiating 227 2 times the luminosity of the Sun from its photosphere at an effective temperature of 8 720 K 8 This anomalously high temperature and an absolute magnitude of 0 98 2 may indicate it is on the verge of evolving into a giant star 7 An infrared excess has been detected from an orbiting circumstellar disk 10 A black body fit to the data yields a mean dust temperature of 160 K and an orbital radius of 42 5 AU 8 In some Arabic star charts it is listed as أخفى الفرقدين ʼakhfa al farqadayn meaning the dimmer of the two calves and paired with h Ursae Minoris as ʼanwar al farqadayn the brighter of the two calves The names may originally refer to a pair of Ibexes and are more properly applied to g UMi and b UMi respectively the brighter two stars in the rectangle of Ursa Minor 15 References edit a b c d e f van Leeuwen F 2007 Validation of the new Hipparcos reduction Astronomy and Astrophysics 474 2 653 664 arXiv 0708 1752 Bibcode 2007A amp A 474 653V doi 10 1051 0004 6361 20078357 S2CID 18759600 a b c d e f 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 Cowley 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 Johnson 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 a b Frolov M S April 1970 List of Probable Delta Scuti Stars Information Bulletin on Variable Stars 427 1 Bibcode 1970IBVS 427 1F a b Gontcharov G A November 2006 Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system Astronomy Letters 32 11 759 771 arXiv 1606 08053 Bibcode 2006AstL 32 759G doi 10 1134 S1063773706110065 S2CID 119231169 a b Kaler James B Alifa al Farkadain Stars University of Illinois Retrieved 21 June 2014 a b c d e Cotten Tara H Song Inseok July 2016 A Comprehensive Census of Nearby Infrared Excess Stars The Astrophysical Journal Supplement Series 225 1 24 arXiv 1606 01134 Bibcode 2016ApJS 225 15C doi 10 3847 0067 0049 225 1 15 S2CID 118438871 15 a b van Belle Gerard T March 2012 Interferometric observations of rapidly rotating stars The Astronomy and Astrophysics Review 20 1 51 arXiv 1204 2572 Bibcode 2012A amp ARv 20 51V doi 10 1007 s00159 012 0051 2 S2CID 119273474 a b c 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 zet UMi SIMBAD Centre de donnees astronomiques de Strasbourg Retrieved 2021 01 08 Eggleton P P Tokovinin A A September 2008 A catalogue of multiplicity among bright stellar systems Monthly Notices of the Royal Astronomical Society 389 2 869 879 arXiv 0806 2878 Bibcode 2008MNRAS 389 869E doi 10 1111 j 1365 2966 2008 13596 x S2CID 14878976 Harrington Philip S October 21 2010 Cosmic Challenge The Ultimate Observing List for Amateurs Cambridge University Press p 38 ISBN 9781139493680 a b zet UMi The International Variable Star Index AAVSO Retrieved 16 October 2022 Allen Richard Hinckley 1899 Star names and Their Meanings G E Stechert pp 447 460 Retrieved from https en wikipedia org w index php title Zeta Ursae Minoris amp oldid 1186890334, wikipedia, wiki, book, books, library,

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