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Tau Pegasi

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Tau Pegasi
Location of τ Pegasi (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Pegasus
Right ascension 23h 20m 38.24188s[1]
Declination +23° 44′ 25.2098″[1]
Apparent magnitude (V) +4.58[2]
Characteristics
Spectral type A5 Vp[3]
A8V(n)kA5mA5 (λ Boo)[4]
U−B color index +0.13[5]
B−V color index +0.17[5]
Variable type δ Sct[6]
Astrometry
Radial velocity (Rv)+15.20±1.6[7] km/s
Proper motion (μ) RA: 29.45±0.33[1] mas/yr
Dec.: −9.53±0.27[1] mas/yr
Parallax (π)20.17 ± 0.40 mas[1]
Distance162 ± 3 ly
(49.6 ± 1.0 pc)
Absolute magnitude (MV)1.10[2]
Details
Mass2.14[8] M☉
Radius2.8[9] R☉
Luminosity32[8] L☉
Surface gravity (log g)3.88[10] cgs
Temperature7,709[8] K
Metallicity [Fe/H]−0.28[2] dex
Rotational velocity (v sin i)149[8] km/s
Other designations
Salm, 62 Pegasi, BD+22°4810, FK5 880, GC 32503, HIP 115250, HR 8880, HD 220061, SAO 91186
Database references
SIMBADdata

Tau Pegasi (τ Pegasi, abbreviated Tau Peg, τ Peg), formally named Salm /ˈsɑːm/,[11] is a magnitude 4.6 star 162 light years away in the constellation of Pegasus. With about twice the mass of the Sun and thirty times as luminous, it is a δ Scuti variable star with its brightness changing by a few hundredths of a magnitude over about an hour.

Nomenclature

[edit]

τ Pegasi (Latinised to Tau Pegasi) is the star's Bayer designation.

The star bore the traditional names Salm,[12] Kerb (or El Khereb) and Markab (often spelled Markeb[13]), a name shared with Alpha Pegasi, k Puppis and Kappa Velorum.[14] In 2016, the IAU organized a Working Group on Star Names (WGSN)[15] to catalog and standardize proper names for stars. The WGSN approved the name Salm (a homophone with the planet Samh) for this star and Markeb for the component Kappa Velorum A, both on 5 September 2017. Markab had previously been approved for Alpha Pegasi on 30 June 2016. All three are now so included in the List of IAU-approved Star Names.[11]

In Chinese, 離宮 (Lì Gōng), meaning Resting Palace, refers to an asterism consisting of Tau Pegasi, Lambda Pegasi, Mu Pegasi, Omicron Pegasi, Eta Pegasi and Nu Pegasi.[16] Consequently, the Chinese name for Tau Pegasi itself is 離宮五 (Lì Gōng wǔ), "the Fifth Star of Resting Palace".[17]

Properties

[edit]
A light curve for Tau Pegasi, plotted from Hipparcos data[18]

Tau Pegasi belongs to spectral class A5 Vp,[3] making it an A-type main-sequence star. It is a type of chemically peculiar star with unusually weak spectral lines of iron peak elements, a class known as λ Boötis stars.[4]

Tau Pegasi is a multiperiodic Delta Scuti variable, with reported pulsation periods ranging from 0.94 to 1.30 hours.[19][20][21] It is rotating rapidly with a projected rotational velocity of 150 km/s. Tau Pegasi is radiating nearly 30 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 7,762 K.[21]

References

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  1. ^ a b c d e van 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. ^ a b c 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. Vizier catalog entry
  3. ^ a b Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H.
  4. ^ a b Griffin, R. E.; Gray, R. O.; Corbally, C. J. (2012). "The composite-spectrum binary hypothesis does not explain the λ Bootis stars". Astronomy and Astrophysics. 547: A8. Bibcode:2012A&A...547A...8G. doi:10.1051/0004-6361/201219112. S2CID 120300949.
  5. ^ a b Mermilliod, J. C. (2006). "VizieR Online Data Catalog: Homogeneous Means in the UBV System (Mermilliod 1991)". VizieR On-line Data Catalog: II/168. Originally Published in: Institut d'Astronomie. 2168. Bibcode:2006yCat.2168....0M.Vizier catalog entry
  6. ^ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  7. ^ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 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.
  8. ^ a b c d Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. S2CID 55586789. Vizier catalog entry
  9. ^ Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A. Vizier catalog entry
  10. ^ David, 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. Vizier catalog entry
  11. ^ a b "Naming Stars". IAU.org. Retrieved 16 December 2017.
  12. ^ Allen, Richard Hinckley (1899). Star-names and their meanings. New York, Leipzig [etc.] G.E. Stechert. pp. 329.
  13. ^ Kunitzsch, P. (February 1986), "John of London and his Unknown Arabic Sources", Journal for the History of Astronomy, 17 (1): 51, Bibcode:1986JHA....17...51K, doi:10.1177/002182868601700104, S2CID 118089032
  14. ^ Kostjuk, N. D. (2004). "VizieR Online Data Catalog: HD-DM-GC-HR-HIP-Bayer-Flamsteed Cross Index (Kostjuk, 2002)". VizieR On-line Data Catalog: IV/27A. Originally Published in: Institute of Astronomy of Russian Academy of Sciences (2002). 4027. Bibcode:2004yCat.4027....0K.
  15. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 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 the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
  18. ^ "Light Curve". Hipparcos ESA. ESA. Retrieved 17 February 2022.
  19. ^ Kennelly, E. J.; Brown, T. M.; Kotak, R.; Sigut, T. A. A.; Horner, S. D.; Korzennik, S. G.; Nisenson, P.; Noyes, R. W.; Walker, A.; Yang, S. (March 1998). "The Oscillations of Tau Pegasi". The Astrophysical Journal. 495 (1): 440–457. Bibcode:1998ApJ...495..440K. doi:10.1086/305268. S2CID 119979285.
  20. ^ "tau Peg". International Variable Star Index. AAVSO. Retrieved 6 September 2022.
  21. ^ a b Balona, L. A.; Dziembowski, W. A. (October 1999), "Excitation and visibility of high-degree modes in stars", Monthly Notices of the Royal Astronomical Society, 309 (1): 221–232, Bibcode:1999MNRAS.309..221B, doi:10.1046/j.1365-8711.1999.02821.x
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