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Denebola

From Wikipedia, the free encyclopedia
This article is about the star. For other uses, seeDenebola (disambiguation).
Not to be confused withDeneb,a star in the constellation Cygnus.
Denebola
Location of β Leonis (circled)
Observation data
EpochJ2000EquinoxJ2000
Constellation Leo
Pronunciation /dəˈnɛbələ/,[1]
Right ascension 11h49m03.57834s[2]
Declination +14° 34′ 19.4090″[2]
Apparent magnitude(V) 2.14[3]
Characteristics
Spectral type A3Va[4]
U−Bcolor index +0.07[5]
B−Vcolor index +0.09[5]
Variable type δ Sct[3]
Astrometry
Radial velocity(Rv)−0.2[6]km/s
Proper motion(μ)RA:−497.68[2]mas/yr
Dec.:−114.67[2]mas/yr
Parallax(π)90.91 ± 0.52mas[2]
Distance35.9 ± 0.2ly
(11.00 ± 0.06pc)
Absolute magnitude(MV)+1.93[7]
Details
Mass1.78[8]M☉
Radius1.75±0.02[9]R☉
Luminosity12.9±0.1[9]L☉
Surface gravity(logg)4.0[10]cgs
Temperature8,262±36[9]K
Metallicity[Fe/H]+0.00[8]dex
Rotational velocity(vsini)128[11]km/s
Age100–380[8]Myr
Other designations
Deneb Aleet,β Leonis,94 Leo,BD+15°2383,FK5444,GJ448,HD102647,HIP57632,HR4534,SAO99809,LHS2462,LTT13249[12][13]
Database references
SIMBADdata

Denebolais thesecond-brightest individual starin thezodiacconstellationofLeo.[14]It is the easternmost of the bright stars of Leo. It has theBayer designationBeta Leonisorβ Leonis,which are abbreviatedBeta Leoorβ Leo.Denebola is anA-type main sequence starwith 75% more mass than theSunand 15 times the Sun's luminosity. Based onparallaxmeasurements from theHipparcosastrometry satellite, the star is at a distance of 36light-years(11parsecs) from the Sun. Itsapparent visual magnitudeis 2.14, making it readily visible to the naked eye. Denebola is aDelta Scuti typevariable star,meaning its luminosity varies very slightly over a period of a few hours.

Nomenclature

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Denebola is the most eastward (left) bright star in this stick-figure diagram overlaid on a constellation photograph of Leo

β Leonis(LatinisedtoBetaLeonis) is the star'sBayer designation.InJohann Bayer'sUranometria(1603), it was designated β (Beta) as the second-brightest star in the constellation. It also bears theFlamsteed designationof94 Leonis(assigned on the basis of increasingright ascensionrather than luminosity) and additional designations followed as the star was recorded in subsequentstar catalogues.

The traditional nameDenebolais shortened fromDeneb Alased,from theArabicphraseذنب الاسدðanab al-asad'tail of the lion', as it represents the lion's tail, the star's position in the Leo constellation.[15](DenebinCygnushas a similar name origin.) In theAlphonsine Tablesit was recorded as Denebalezeth.[16]OnR. A. Proctor's 1871 star chart of theNorthern Hemisphereit was designatedDeneb Aleet.In 2016, theInternational Astronomical Unionorganized 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 includedDenebolafor this star. It is now so entered in the IAU Catalog of Star Names.[19]

15th century astronomerUlugh Beg,gives the nameAl Ṣarfah,the Changer (i.e. of the weather), as the star's individual title.[20]Al-Biruni,a Muslim scholar and polymath of the 11th century, wrote of it: "The heat turns away when it rises, and the cold turns away when it disappears."[20]

Ancient Chinese astronomers designated it the first star of the five-star asterism "Seat of the Five Emperors", hence itsChinese nameNgũ đế tọa nhất (Wǔdìzuò-yī).

InHinduastronomy,Denebola corresponds to theNakshatra(a sector along theecliptic) namedUttara Phalgunī(second reddish one).

Denebola, along withSpicaandArcturus,is part of theSpring Triangleasterism, and by extension, also of theGreat Diamondtogether with the starCor Caroli.[21]

Properties

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Denebola is a relatively young star with an age estimated at less than 400 million years. Interferometric observations give a radius that is about 173% that of the Sun. Its high rate of rotation results in an oblate shape with anequatorial bulge.It has 75% more mass than the Sun, which results in a much higher overall luminosity and a shorter life span on themain sequence.[8]

Based upon the star'sspectrum,it has astellar classificationof A3 Va,[4]with theluminosity class'Va' indicating this is a particularly luminous dwarf, amain sequencestar that is generating energy through thenuclear fusionof hydrogen at its core. Theeffective temperatureof Denebola's outer envelope is about8,500K,which results in the white hue typical ofA-type stars.Denebola has a highprojected rotational velocityof 128 km/s, which is of the sameorder of magnitudeas for the very rapidly rotating starAchernar.The Sun, in comparison, has an equatorial rotation velocity of 2 km/s.[10]This star is believed to be aDelta Scuti variablestar that exhibits fluctuations in luminosity of 0.025 magnitudes roughly ten times per day.[22]

Denebola shows a stronginfrared excess,indicating there is a circumstellardebris diskof cool dust in orbit around it.[23]This dust has a temperature of about 120 K (−153 °C). Observations with theHerschel Space Observatoryhave provided resolved images, which show the disk to be located at a mean radius of 39astronomical unitsfrom the star.[24]As theSolar Systemis believed to have formed out of such a disk, Denebola and similar stars such asVegaandBeta Pictorismay be candidate locations forextrasolar planets.

Kinematicstudies have shown that Denebola is part of astellar associationdubbed theIC 2391supercluster. All the stars of this group share a roughly common motion through space, although they are not gravitationally bound. This suggests that they were born in the same location, and perhaps initially formed anopen cluster.Other stars in this association includeAlpha Pictoris,Beta Canis Minorisand theopen clusterIC 2391. In total more than sixty probable members of the group have been identified.[25]

See also

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References

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  1. ^"Denebola".Merriam-Webster.com Dictionary.
  2. ^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.S2CID18759600.
  3. ^abSamus, N. N.; et al. (2017). "General Catalogue of Variable Stars".Astronomy Reports.5.1.61(1): 80–88.Bibcode:2017ARep...61...80S.doi:10.1134/S1063772917010085.S2CID125853869.
  4. ^abGray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Robinson, P. E. (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.S2CID119417105.
  5. ^abHoffleit, D.;Jaschek, C.,eds. (1991).The Bright Star Catalogue.New Haven: Yale University Observatory.Bibcode:1991bsc..book.....H.
  6. ^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.
  7. ^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.S2CID119257644.
  8. ^abcdDi Folco, E.; et al. (2004)."VLTI near-IR interferometric observations of Vega-like stars".Astronomy and Astrophysics.426(2): 601–617.Bibcode:2004A&A...426..601D.doi:10.1051/0004-6361:20047189.
  9. ^abc Baines, Ellyn K.; Clark III, James H.; Schmitt, Henrique R.; Stone, Jordan M.; von Braun, Kaspar (2023-12-01)."33 New Stellar Angular Diameters from the NPOI, and Nearly 180 NPOI Diameters as an Ensemble".The Astronomical Journal.166(6): 268.Bibcode:2023AJ....166..268B.doi:10.3847/1538-3881/ad08be.ISSN0004-6256.
  10. ^abAcke, B.; Waelkens, C. (2004). "Chemical analysis of 24 dusty (pre-)main sequence stars".Astronomy and Astrophysics.427(3): 1009–1017.arXiv:astro-ph/0408221.Bibcode:2004A&A...427.1009A.doi:10.1051/0004-6361:20041460.S2CID16615394.
  11. ^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.S2CID18475298.
  12. ^"* bet Leo".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2007-06-18.
  13. ^"Denebola".Alcyone.Retrieved2006-08-10.
  14. ^The two components of theγ Leonisdouble star, which are unresolved to the naked eye, have a combined magnitude brighter than it.
  15. ^Allen, R. H.(1963).Star Names: Their Lore and Meaning(Reprint ed.). New York, NY: Dover Publications Inc. p.258.ISBN0-486-21079-0.Retrieved2010-12-12.
  16. ^Kunitzsch, Paul (1986). "The Star Catalogue Commonly Appended to the Alfonsine Tables".Journal for the History of Astronomy.17(49): 89–98.Bibcode:1986JHA....17...89K.doi:10.1177/002182868601700202.S2CID118597258.
  17. ^"IAU Working Group on Star Names (WGSN)".Retrieved22 May2016.
  18. ^"Bulletin of the IAU Working Group on Star Names, No. 1"(PDF).Retrieved28 July2016.
  19. ^"IAU Catalog of Star Names".Retrieved28 July2016.
  20. ^ab"LacusCurtius • Allen's Star Names — Leo".Retrieved2024-06-02.
  21. ^Rao, Joe (June 11, 2012)."How to See Mars and Saturn in Night Sky's Spring Triangle".Space.com.Archivedfrom the original on 2023-05-29.Retrieved2024-01-29.
  22. ^Mkrtichian, D. E.; Yurkov, A. (5–7 November 1997). "β Leo - Back to Delta Scuti Stars?".Proceedings of the 20th Stellar Conference of the Czech and Slovak Astronomical Institutes.Brno, Czech Republic: Dordrecht, D. Reidel Publishing Co. p. 172.Bibcode:1998vsr..conf..143M.ISBN80-85882-08-6.
  23. ^Cote, J. (1987). "B and A type stars with unexpectedly large colour excesses at IRAS wavelengths".Astronomy and Astrophysics.181(1): 77–84.Bibcode:1987A&A...181...77C.
  24. ^Matthews, B. C.; et al. (2010). "Resolving debris discs in the far-infrared: Early highlights from the DEBRIS survey".Astronomy and Astrophysics.518:L135.arXiv:1005.5147.Bibcode:2010A&A...518L.135M.doi:10.1051/0004-6361/201014667.S2CID54013449.
  25. ^Eggen, O. J. (1991). "The IC 2391 supercluster".Astronomical Journal.102:2028–2040.Bibcode:1991AJ....102.2028E.doi:10.1086/116025.

Further reading

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  • Kaler, Jim."Denebola".Stars.University of Illinois.Retrieved2012-01-14.
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