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Zeta Pegasi

From Wikipedia, the free encyclopedia
Star in the constellation Pegasus
Zeta Pegasi
Location of ζ Pegasi (circled)
Observation data
EpochJ2000.0      EquinoxJ2000.0
ConstellationPegasus
Right ascension22h 41m 27.72072s[1]
Declination+10° 49′ 52.9079″[1]
Apparent magnitude (V)+3.414[2]
Characteristics
Spectral typeB8 V[3]
U−Bcolor index−0.181[2]
B−Vcolor index−0.088[2]
Variable typeSPB[4]
Astrometry
Radial velocity (Rv)+7.0[5] km/s
Proper motion (μ)RA: +77.22[1]mas/yr
Dec.: −11.38[1]mas/yr
Parallax (π)15.96±0.19 mas[1]
Distance204 ± 2 ly
(62.7 ± 0.7 pc)
Details
Mass3.22[6] M☉
Radius4.23±0.25[7] R☉
Luminosity224[6] L☉
Surface gravity (log g)3.67±0.05[8] cgs
Temperature12,300±1,000[7] K
Metallicity [Fe/H]+0.06[6] dex
Rotational velocity (v sin i)140[9] – 210[10] km/s
Age120[10] Myr
Other designations
Homam,Zeta Peg, ζ Peg,42 Peg,BD+10°4797,FK5 855,HD 214923,HIP 112029,HR 8634,SAO 108103[11]
Database references
SIMBADdata

Zeta Pegasi orζ Pegasi, formally namedHomam (/ˈhoʊmæm/),[12][13] is a single[14]star in the northernconstellation ofPegasus. With anapparent visual magnitude of +3.4,[2] this star is bright enough to be seen with thenaked eye and is one of thebrighter members of Pegasus.Parallax measurements place it at a distance of around 204light-years (62.7parsecs) from theSun.[1]

Nomenclature

[edit]

ζ Pegasi (Latinised toZeta Pegasi) is the star'sBayer designation.

It bore the traditional nameHomam, meaning "Man of High Spirit" or "Lucky Star of High Minded". In 2016, theInternational Astronomical Union organized aWorking Group on Star Names (WGSN)[15] to catalogue and standardize proper names for stars. The WGSN approved the nameHomam for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.[13]

InChinese,雷電 (Léi Diàn), meaningThunder and Lightning, refers to an asterism consisting ζ Pegasi,ξ Pegasi,σ Pegasi,55 Pegasi,66 Pegasi and70 Pegasi.[16] Consequently, theChinese name for ζ Pegasi itself is雷電一 (Léi Diàn yī), "the First Star of Thunder and Lightning".[17]

Properties

[edit]
Alight curve for Zeta Pegasi, adapted from Goebel (2007)[4]

This star has astellar classification of B8 V,[3] which identifies it as a largeB-type main sequence star that is generating energy through thenuclear fusion of hydrogen at its core. The radius of this star is about four times that of the Sun.[7] In 2007, John H. Goebel showed that Zeta Pegasi is a variable star, using data obtained fromGravity Probe B.[4] It is aslowly pulsating B star that varies slightly in luminosity with a period of22.952±0.804 hours, completing 1.04566 cycles per day.[4] Zeta Pegasi is about 120[10] million years old and is rotating rapidly with aprojected rotational velocity in the range of140[9] to 210[10] km/s. Theeffective temperature of itsouter envelope is around12,300 K,[7] giving it the characteristic blue-white glow of aB-type star.[18]

Zeta Pegasi has been examined forinfrared excess that may indicate the presence of circumstellar matter, but none was found.[19] This star does have twooptical companions. The first is a magnitude 11.6 star at anangular separation of68 arcseconds along aposition angle of 139°, as of 1997.[4] The second is an 11th magnitude star at a separation of177 arcseconds with a position angle of 5°.[5] Zeta Pegasi is not known to be a member of astellar association.[19]

References

[edit]
  1. ^abcdefvan 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. ^abcdGutierrez-Moreno, Adelina; et al. (1966), "A System of photometric standards",Publications of the Department of Astronomy University of Chile,1:1–17,Bibcode:1966PDAUC...1....1G
  3. ^abPalmer, D. R.; et al. (1968), "The radial velocities spectral types and projected rotational velocities of 633 bright northern A stars",Royal Observatory Bulletin,135: 385,Bibcode:1968RGOB..135..385P
  4. ^abcdeGoebel, John H. (May 2007), "Gravity Probe B Photometry and Observations of ζ Pegasi: An SPB Variable Star",The Publications of the Astronomical Society of the Pacific,119 (855):483–493,Bibcode:2007PASP..119..483G,doi:10.1086/518618
  5. ^abWielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions",Veroeffentlichungen des Astronomischen Rechen-Instituts Heidelberg,35 (35): 1,Bibcode:1999VeARI..35....1W
  6. ^abcChallouf, M.; et al. (2014), "Improving the surface brightness-color relation for early-type stars using optical interferometry⋆",Astronomy & Astrophysics,570: A104,arXiv:1409.1351,Bibcode:2014A&A...570A.104C,doi:10.1051/0004-6361/201423772,S2CID 14624307
  7. ^abcdGordon, Kathryn D.; Gies, Douglas R.; Schaefer, Gail H.; Huber, Daniel; Ireland, Michael (March 2019)."Angular Sizes, Radii, and Effective Temperatures of B-type Stars from Optical Interferometry with the CHARA Array".The Astrophysical Journal.873 (1): 91.Bibcode:2019ApJ...873...91G.doi:10.3847/1538-4357/ab04b2.S2CID 125181833.
  8. ^Fitzpatrick, E. L.; Massa, D. (March 2005), "Determining the Physical Properties of the B Stars. II. Calibration of Synthetic Photometry",The Astronomical Journal,129 (3):1642–1662,arXiv:astro-ph/0412542,Bibcode:2005AJ....129.1642F,doi:10.1086/427855,S2CID 119512018
  9. ^abAbt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002), "Rotational Velocities of B Stars",The Astrophysical Journal,573 (1):359–365,Bibcode:2002ApJ...573..359A,doi:10.1086/340590
  10. ^abcdRieke, G. H.; et al. (February 2005), "Decay of Planetary Debris Disks",The Astrophysical Journal,620 (2):1010–1026,Bibcode:2005ApJ...620.1010R,CiteSeerX 10.1.1.579.8956,doi:10.1086/426937,S2CID 54676993
  11. ^"zet Peg".SIMBAD.Centre de données astronomiques de Strasbourg. Retrieved2012-03-01.
  12. ^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
  13. ^abIAU Catalog of Star Names, retrieved28 July 2016
  14. ^Roberts, Lewis C. Jr.; Turner, Nils H.; ten Brummelaar, Theo A. (February 2007), "Adaptive Optics Photometry and Astrometry of Binary Stars. II A Multiplicity Survey of B Stars",The Astronomical Journal,133 (2):545–552,Bibcode:2007AJ....133..545R,CiteSeerX 10.1.1.549.4623,doi:10.1086/510335,S2CID 10416471
  15. ^IAU Working Group on Star Names (WGSN),International Astronomical Union, retrieved22 May 2016
  16. ^(in Chinese)中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005,ISBN 978-986-7332-25-7.
  17. ^(in Chinese)香港太空館 - 研究資源 - 亮星中英對照表Archived 2008-10-25 at theWayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
  18. ^"The Colour of Stars",Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived fromthe original on 2013-12-03, retrieved2012-01-16
  19. ^abSu, 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
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