Lambda Boötis

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λ Boötis
Location of λ Boötis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Boötes
Right ascension 14h 16m 23.018s[1]
Declination +46° 05′ 17.90″[1]
Apparent magnitude (V) +4.18[2]
Characteristics
Spectral type A0p λB[3]
U−B color index +0.05[2]
B−V color index +0.08[2]
Variable type δ Sct[4]
Astrometry
Radial velocity (Rv)−7.9±1.6[5] km/s
Proper motion (μ) RA: −187.698 mas/yr[1]
Dec.: 159.309 mas/yr[1]
Parallax (π)32.5885±0.1410 mas[1]
Distance100.1 ± 0.4 ly
(30.7 ± 0.1 pc)
Absolute magnitude (MV)+1.71±0.23[6]
Details
Mass1.66+0.19
−0.16[7] M☉
Radius1.7[8] R☉
Luminosity19.1+9.0
−6.1[7] L☉
Surface gravity (log g)4.188[9] cgs
Temperature8720[10] K
Rotational velocity (v sin i)100[9] km/s
Age2.8+1.1
−0.8[7] Gyr
Other designations
Xuange, λ Boo, 19 Boötis, BD+46°1949, FK5 527, GC 19273, GJ 3837, HD 125162, HIP 69732, HR 5351, SAO 44965[11]
Database references
SIMBADdata

Lambda Boötis is a star in the northern constellation of Boötes. Its name is a Bayer designation that is Latinized from λ Boötis, and abbreviated Lam Boo or λ Boo. It has the official name Xuange,[12] pronounced /ˈʃwɛnɡə/.[citation needed] With an apparent visual magnitude of +4.18, it is faintly visible to the naked eye. Based on parallax measurements, it is 100.1 light-years (30.7 pc) distant from Earth.[1] This star is drifting closer to the Sun with a radial velocity of −8 km/s.[5]

This is a white hued A-type main-sequence star with a stellar classification of A0p λB.[3] It is the prototype of a group of rare stars known as Lambda Boötis stars, all of which are dwarf stars with unusually low abundances of metals in their spectra. Its diameter has been directly measured to be 1.7 times that of the Sun.[8] This is a Delta Scuti variable star with a period of 33.1 minutes and an amplitude of 0.0020 in visual magnitude.[4]

This star displays an infrared excess that may be the result of a circumstellar disk of orbiting debris, or else a bow wave from its motion through the interstellar medium.[13]

Nomenclature

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λ Boötis (Latinised to Lambda Boötis) is the star's Bayer designation.

In Chinese astronomy, Lambda Boötis is called 玄戈, Pinyin: Xuángē, meaning 'sombre lance', because this star is marking itself and standing alone in the Sombre Lance asterism, Purple Forbidden enclosure (see : Chinese constellations).[14] 玄戈 (Xuángē) westernized into Heuen Ko, but that name was assigned to Gamma Boötis by R. H. Allen, with the meaning of 'the heavenly spear'.[15] In 2016, the IAU organized a Working Group on Star Names (WGSN)[16] to catalog and standardize proper names for stars. The WGSN approved the name Xuange for Lambda Boötis on 30 June 2017 and it is now so included in the List of IAU-approved Star Names.[12]

This star, along with the Aselli (Theta Boötis, Iota Boötis and Kappa Boötis), were Al Aulād al Dhiʼbah (ألعولد ألذعب - al aulād al dhiʼb), "the Whelps of the Hyenas".[17] Al Aulād al Dhiʼbah or Aulad al Thiba was the title of this star in a 1971 NASA memorandum.[18]

References

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  1. ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ a b c 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.
  3. ^ a b Abt, Helmut A.; Morrell, Nidia I. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". Astrophysical Journal Supplement. 99: 135. Bibcode:1995ApJS...99..135A. doi:10.1086/192182.
  4. ^ a b Chang, S.-W.; et al. (2013). "Statistical Properties of Galactic δ Scuti Stars: Revisited". The Astronomical Journal. 145 (5): 10. arXiv:1303.1031. Bibcode:2013AJ....145..132C. doi:10.1088/0004-6256/145/5/132. S2CID 118900730. 132.
  5. ^ 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.
  6. ^ Paunzen, E.; et al. (November 2002). "The status of Galactic field λ Bootis stars in the post-Hipparcos era". Monthly Notices of the Royal Astronomical Society. 336 (3): 1030–1042. arXiv:astro-ph/0207488. Bibcode:2002MNRAS.336.1030P. doi:10.1046/j.1365-8711.2002.05865.x. S2CID 2389489.
  7. ^ a b c Montesinos, B.; et al. (March 2009). "Parameters of Herbig Ae/Be and Vega-type stars". Astronomy and Astrophysics. 495 (3): 901–917. arXiv:0811.3557. Bibcode:2009A&A...495..901M. doi:10.1051/0004-6361:200810623. S2CID 14972955.
  8. ^ a b Ciardi; et al. (2007). "The Angular Diameter of λ Boötis". The Astrophysical Journal. 659 (2): 1623–1628. arXiv:astro-ph/0612723. Bibcode:2007ApJ...659.1623C. doi:10.1086/512077. S2CID 17861605.
  9. ^ a b Song, Inseok; Caillault, J.-P.; Barrado y Navascués, David; Stauffer, John R. (February 2001). "Ages of A-Type Vega-like Stars from uvbyβ Photometry". The Astrophysical Journal. 546 (1): 352–357. arXiv:astro-ph/0010102. Bibcode:2001ApJ...546..352S. doi:10.1086/318269. S2CID 18154947.
  10. ^ Martínez-Galarza, J. R.; et al. (March 2009). "Infrared Emission by Dust Around λ Bootis Stars: Debris Disks or Thermally Emitting Nebulae?". The Astrophysical Journal. 694 (1): 165–173. arXiv:0812.2198. Bibcode:2009ApJ...694..165M. doi:10.1088/0004-637X/694/1/165. S2CID 14298654.
  11. ^ "lam boo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2025-05-29.
  12. ^ a b "Naming Stars". IAU.org. Retrieved 16 December 2017.
  13. ^ Draper, Z. H.; et al. (2016). "IR excesses around nearby Lambda Boo stars are caused by debris discs rather than ISM bow waves". Monthly Notices of the Royal Astronomical Society. 456 (1): 459. arXiv:1511.05919. Bibcode:2016MNRAS.456..459D. doi:10.1093/mnras/stv2696. S2CID 118343020.
  14. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 14 日 Archived 2011-07-16 at the Wayback Machine
  15. ^ Allen, Richard Hinckley. "Star Names — Their Lore and Meaning: Boötes". Retrieved 2025-05-29.
  16. ^ "IAU Working Group on Star Names (WGSN)". International Astronomical Union. Retrieved 2016-05-22.
  17. ^ Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York, NY: Dover Publications Inc. p. 105. ISBN 978-0-486-21079-7. Retrieved 2010-12-12.{{cite book}}: CS1 maint: ignored ISBN errors (link)
  18. ^ Rhoads, Jack W. (November 15, 1971). Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars. Jet Propulsion Laboratory, California Institute of Technology. Retrieved 2025-05-29.
[edit]
  • Hoffleit; et al. (1991). "HR 5351". Bright Star Catalogue (5th Revised ed.). Retrieved 2017-09-13.
  • "lam Bo0". Aladin previewer. Centre de Données astronomiques de Strasbourg. Retrieved 2017-09-12.