Lambda Boötis

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title: "Lambda Boötis" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["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"] description: "Star in the constellation Boötes" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/Lambda_Boötis" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Star in the constellation Boötes ::

| name = λ Boötis | image = |image=Boötes constellation map.svg|alt=|float=center|width=220 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=λ Boötis |x=656|y=207 | caption = Location of λ Boötis (circled) | epoch = J2000.0 | constell = Boötes | ra = | dec = | appmag_v = +4.18 | class = A0p λB | b-v = +0.08 | u-b = +0.05 | variable = δ Sct | radial_v = | prop_mo_ra = −187.698 | prop_mo_dec = 159.309 | pm_footnote = | parallax = 32.5885 | p_error = 0.1410 | parallax_footnote = | absmag_v = | mass = | radius = | gravity = 4.188 | luminosity = | temperature = | metal_fe = | rotational_velocity = 100 | age_gyr = | names = | Simbad = lam+Boo 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, pronounced . With an apparent visual magnitude of +4.18, it is faintly visible to the naked eye. Based on parallax measurements, it is 100.1 ly distant from Earth. This star is drifting closer to the Sun with a radial velocity of −8 km/s.

::figure[src="https://upload.wikimedia.org/wikipedia/commons/f/fa/LamBooLightCurve.png" caption="TESS]]'' data"] ::

This is a white hued A-type main-sequence star with a stellar classification of A0p λB. 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. This is a Delta Scuti variable star with a period of 0.0230 days and an amplitude of 0.0020 in visual magnitude.

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.

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). 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'. In 2016, the IAU organized a Working Group on Star Names (WGSN) 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.

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". Al Aulād al Dhiʼbah or Aulad al Thiba was the title of this star in a 1971 NASA memorandum.

References

| title=lam boo | access-date=2025-05-29 }}

| title=Star Names: Their Lore and Meaning | last=Allen | first=R. H. | author-link=Richard Hinckley Allen | page=105 | year=1963 | isbn=((978-0-486-21079-7)) | edition=Reprint | publisher=Dover Publications Inc | location=New York, NY | url=https://archive.org/details/starnamestheirlo00alle/page/105 | access-date=2010-12-12 | url-access=registration }}

| title=Star Names — Their Lore and Meaning: Boötes | first=Richard Hinckley | last=Allen | url=http://www.constellationsofwords.com/stars/Seginus.html | access-date=2025-05-29 }}

| title=Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars | first=Jack W. | last=Rhoads | date=November 15, 1971 | publisher=Jet Propulsion Laboratory, California Institute of Technology | url=https://ntrs.nasa.gov/citations/19720005197 | access-date=2025-05-29 }}

| title=The Angular Diameter of λ Boötis | author=Ciardi | last2=Van Belle | first2=Gerard T. | last3=Boden | first3=Andrew F. | last4=Ten Brummelaar | first4=T. | last5=McAlister | first5=H. A. | last6=Bagnuolo, Jr. | first6=W. G. | last7=Goldfinger | first7=P. J. | last8=Sturmann | first8=J. | last9=Sturmann | first9=L. | last10=Turner | first10=N. | last11=Berger | first11=D. H. | last12=Thompson | first12=R. R. | last13=Ridgway | first13=S. T. | bibcode=2007ApJ...659.1623C|arxiv = astro-ph/0612723 | display-authors=1 | journal=The Astrophysical Journal | volume=659 | issue=2 | pages=1623–1628 | year=2007 | doi=10.1086/512077 | s2cid=17861605 }}

| title=IAU Working Group on Star Names (WGSN) | publisher=International Astronomical Union | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | access-date=2016-05-22 | archive-date=2016-06-10 | archive-url=https://web.archive.org/web/20160610172014/https://www.iau.org/science/scientific_bodies/working_groups/280/ | url-status=dead

| title=IR excesses around nearby Lambda Boo stars are caused by debris discs rather than ISM bow waves | last1=Draper | first1=Z. H. | last2=Matthews | first2=B. C. | last3=Kennedy | first3=G. M. | last4=Wyatt | first4=M. C. | last5=Venn | first5=K. A. | last6=Sibthorpe | first6=B. | journal=Monthly Notices of the Royal Astronomical Society | volume=456 | issue=1 | pages=459 | year=2016 | display-authors=1 | bibcode=2016MNRAS.456..459D | doi=10.1093/mnras/stv2696 | doi-access=free | arxiv=1511.05919 | s2cid=118343020 }}

| title=Statistical Properties of Galactic δ Scuti Stars: Revisited | last1=Chang | first1=S.-W. | last2=Protopapas | first2=P. | last3=Kim | first3=D.-W. | last4=Byun | first4=Y.-I. | journal =The Astronomical Journal | volume=145 | issue=5 | id=132 | pages=10 | year=2013 | bibcode=2013AJ....145..132C | arxiv=1303.1031 | doi=10.1088/0004-6256/145/5/132 | s2cid=118900730 }}

References

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