Lambda Boötis

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Short description: Star in the constellation Boötes
λ Boötis
Location of λ Boötis (circled)
Observation data
Equinox J2000.0]] (ICRS)
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[1] mas/yr
Dec.: 159.309[1] mas/yr
Parallax (π)32.5885 ± 0.1410[1] mas
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☉
Radius1.70±0.10[8] R☉
Luminosity16.3±0.6[8] L☉
Surface gravity (log g)4.188[9] cgs
Temperature8,887±242[8] 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[10]
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,[11] 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]

A light curve for Lambda Boötis, plotted from TESS data[12]

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

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.[11]

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

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 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. ↑ 3.0 3.1 Abt, Helmut A.; Morrell, Nidia I. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". Astrophysical Journal Supplement 99: 135. doi:10.1086/192182. Bibcode: 1995ApJS...99..135A. 
  4. ↑ 4.0 4.1 Chang, S.-W. et al. (2013). "Statistical Properties of Galactic δ Scuti Stars: Revisited". The Astronomical Journal 145 (5): 10. doi:10.1088/0004-6256/145/5/132. 132. Bibcode: 2013AJ....145..132C. 
  5. ↑ 5.0 5.1 Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759–771. doi:10.1134/S1063773706110065. Bibcode: 2006AstL...32..759G. 
  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. doi:10.1046/j.1365-8711.2002.05865.x. Bibcode: 2002MNRAS.336.1030P. 
  7. ↑ 7.0 7.1 Montesinos, B. et al. (March 2009). "Parameters of Herbig Ae/Be and Vega-type stars". Astronomy and Astrophysics 495 (3): 901–917. doi:10.1051/0004-6361:200810623. Bibcode: 2009A&A...495..901M. 
  8. ↑ 8.0 8.1 8.2 8.3 Ciardi et al. (2007). "The Angular Diameter of λ Boötis". The Astrophysical Journal 659 (2): 1623–1628. doi:10.1086/512077. Bibcode: 2007ApJ...659.1623C. 
  9. ↑ 9.0 9.1 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. doi:10.1086/318269. Bibcode: 2001ApJ...546..352S. 
  10. ↑ "lam boo". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=lam+boo. 
  11. ↑ 11.0 11.1 "Naming Stars". IAU.org. https://www.iau.org/public/themes/naming_stars/. 
  12. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html. 
  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. doi:10.1093/mnras/stv2696. Bibcode: 2016MNRAS.456..459D. 
  14. ↑ Script error: The function "in_lang" does not exist. AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 14 日
  15. ↑ Allen, Richard Hinckley. "Star Names — Their Lore and Meaning: Boötes". http://www.constellationsofwords.com/stars/Seginus.html. 
  16. ↑ "IAU Working Group on Star Names (WGSN)". International Astronomical Union. https://www.iau.org/science/scientific_bodies/working_groups/280/. 
  17. ↑ Star Names: Their Lore and Meaning (Reprint ed.). New York, NY: Dover Publications Inc. 1963. p. 105. ISBN ((978-0-486-21079-7)). https://archive.org/details/starnamestheirlo00alle/page/105. Retrieved 2010-12-12. 
  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. https://ntrs.nasa.gov/citations/19720005197. Retrieved 2025-05-29. 



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Categories: [A-type main-sequence stars] [Lambda Boötis stars] [Delta Scuti variables] [Circumstellar disks] [Boötes] [Bayer objects] [Bright Star Catalogue objects] [Durchmusterung objects] [Flamsteed objects] [Gliese and GJ objects] [Henry Draper Catalogue objects] [Hipparcos objects] [Stars with proper names]

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