{{short description|Triple star system in the constellation Scorpius}} {{Starbox begin | name=λ Scorpii }} {{Starbox image | image = {{Location mark |image=Scorpius constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=12|mark_link=Shaula|x=247|y=712 }} | caption = Location of λ Scorpii (circled)}} {{Starbox observe | pronounce = {{IPAc-en|'|sh|ɔː|l|@}}<ref name=Kunitzsch/><ref name="IAU-CSN"/> | epoch = J2000 | ra = {{RA|17|33|36.520}}<ref name=hipparcos/> | dec = {{DEC|−37|06|13.76}}<ref name=hipparcos/> | appmag_v = 1.63<ref name=tycho2/> | constell = Scorpius }} {{Starbox character | type = Main sequence (A and B)<ref name=tango/> + pre-main sequence (a)<ref name=handler/> | class = {{nowrap|B1.5IV + B2IV}}<ref name=tango/><ref name=variability/> | b-v = −0.240<ref name=hamdy/> | u-b = −0.880<ref name=hamdy/> | variable = Beta Cephei (Aa1)<ref name=handler/> + {{nowrap|Algol (Aa1/2) <ref name=vsx/>}} }} {{Starbox astrometry | radial_v = −3.00<ref name=Gontcharov2006/> | prop_mo_ra = −8.90<ref name=hipparcos/> | prop_mo_dec = −29.95 | pm_footnote = <ref name=hipparcos/> | parallax = 5.71 | p_error = 0.90 | parallax_footnote = <ref name=hipparcos/> | absmag_v = −3.70<ref name=balona/> }} {{Starbox orbit | reference = <ref name=msc/> | primary = Aa | name = Ab | period = 2.8825 | axis_unitless = {{val|49.3|ul=mas}} | eccentricity = 0.121 | inclination = 77.2 }} {{Starbox orbit | reference = <ref name=msc/> | primary = Aa1 | name = Aa2 | period_unitless = {{val|5.9520|ul=d}} | eccentricity = 0.26 | k1 = 39.3 }} {{Starbox detail | component1 = λ Sco Aa1 (A) | mass = 10.4<ref name=tango/> | radius = {{val|8.8|1.2}}<ref name=handler/> | luminosity = 36,300<ref name=handler/> | temperature = {{val|25000|1000|fmt=commas}}<ref name=handler/> | metal_fe=|gravity = 3.8<ref name=variability/> | rotational_velocity = 150<ref name=handler/> | rotation = {{val|3.4|0.5}}<ref name=handler/> days | age_myr = | component2 = λ Sco Aa2 (a) | mass2 = {{val|2.0|0.2}}<ref name=handler/> | radius2 = {{val|1.5|0.2}}<ref name=handler/> }} {{Starbox detail|no_heading=y | component1 = λ Sco Ab (B) | mass = 8.1<ref name=tango/> | radius = {{val|4.7|1.0}}<ref name=handler/> | temperature = {{val|25000|1000|fmt=commas}}<ref name=handler/> | gravity = 4.0<ref name=variability/> }} {{Starbox catalog | names = {{odlist | name=Shaula | F=35 Scorpii, 35 Sco | HR=6527 | CD=-37 11673 | HD=158926 | SAO=208954 | FK5=652 | HIP=85927 | CCDM=J17336-3706A }} }} {{Starbox reference|Simbad=Lambda+Sco}} {{Starbox end}}
'''Lambda Scorpii''' is a triple star system and the second-brightest object in the constellation of Scorpius. It is formally named '''Shaula'''; ''Lambda Scorpii'' is its Bayer designation, which is Latinised from '''λ Scorpii''' and abbreviated '''Lambda Sco''' or '''λ Sco'''. With an apparent visual magnitude of 1.63, it is one of the brightest stars in the night sky.
==Nomenclature==
''λ Scorpii'' (Latinised to ''Lambda Scorpii'') is the star system's Bayer designation.
It bore the traditional name ''Shaula'', which comes from the Arabic الشولاء ''al-šawlā´'' meaning 'the raised [tail]', as it is found in the tail of Scorpius, the scorpion. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)<ref name="WGSN"/> to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016<ref name="WGSN1"/> included a table of the first two batches of names approved by the WGSN, which included ''Shaula'' for the star λ Scorpii Aa1.
In Indian astronomy, it is part of the asterism Mula with other stars in the tail of Scorpius. Mūla ("root") (Devanagari मूल/मूळ) (Tamil: மூலம்) is the 19th nakshatra or "lunar mansion" in Vedic astrology. The symbol of Mula is a bunch of roots tied together (reticulated roots) or an 'elephant goad' (ankusha).<ref name="ASE"/>
In Chinese, {{lang|zh|尾宿}} ({{lang|zh-Latn|Wěi Xiù}}), meaning ''Tail'', refers to an asterism consisting of λ Scorpii, ε Scorpii, ζ<sup>1</sup> Scorpii, ζ<sup>2</sup> Scorpii, η Scorpii, θ Scorpii, ι<sup>1</sup> Scorpii, ι<sup>2</sup> Scorpii, κ Scorpii, μ<sup>1</sup> Scorpii, and υ Scorpii.<ref name=zh/> Consequently, the Chinese name for λ Scorpii itself is {{lang|zh|尾宿八}} ({{lang|zh-Latn|Wěi Xiù bā}}), "the Eighth Star of Tail".<ref name=chinengstars/>
Together with υ Scorpii (Lesath), Shaula is listed in the Babylonian compendium MUL.APIN as <sup>d</sup>Sharur<sub>4</sub> u <sup>d</sup>Shargaz, meaning "Sharur and Shargaz".<ref name=Rogers/> In Coptic, these two stars were called ''Minamref''.<ref name=Burnham/>
The indigenous Boorong people of northwestern Victoria (Australia) named it (together with Upsilon Scorpii) ''Karik Karik'',<ref name=hamacher/> "the Falcons".<ref name=stanbridge/>
==Properties== [[File:LambdaScoLightCurve.png|thumb|left|A light curve for Lambda Scorpii, plotted from ''TESS'' data.<ref name=MAST/> The large dips in brightness are eclipses, and the rapid oscillations show the Beta Cephei variability.]] Lambda Scorpii is located approximately 570 light-years away from the Sun.
Spectroscopic and interferometric observations have shown that it is actually a triple star system consisting of two B-type stars and a pre-main-sequence star.<ref name=handler/> The primary star is a Beta Cephei variable star with rapid brightness changes of about a hundredth of a magnitude.<ref name=variability/><ref name=tango/> The pre-main-sequence star has an orbital period of 6 days and the B-type companion has a period of 1,053 days. The three stars lie in the same orbital plane, strongly suggesting that they were formed at the same time. The masses of the primary, pre-main-sequence star and the B-type companion are 14.5, 2.0 and 10.6 solar masses, respectively. The age of the system is estimated to be in the range 10–13 million years. Shaula Aa1 has sufficient mass to explode as a supernova.<ref>{{Cite web |title=Shaula |url=http://stars.astro.illinois.edu/sow/shaula.html |access-date=2026-05-09 |website=stars.astro.illinois.edu}}</ref>
A 15th-magnitude star has a separation of 42 arcseconds, whereas a 12th-magnitude star is 95 arcseconds away. It is not known whether or not these components are physically associated with Lambda Scorpii. If they both were, the first would have a projected linear separation of approximately 7,500 astronomical units (AU) and the second approximately 17,000 AU (0.27 light-years) away. Gaia Data Release 3 reports that the fainter of these two stars is a little larger and brighter than the sun and about 420 light years away,<ref name=dr3-1>{{cite Gaia DR3|5962581880247644288}}</ref> while the brighter star is a background object.<ref name=dr3-2>{{cite Gaia DR3|5962570094857321472}}</ref>
==In culture==
Shaula appears on the flag of Brazil, symbolizing the state of Rio Grande do Norte.
USS ''Shaula'' (AK-118) was a U.S. Navy ''Crater''-class cargo ship named after the star.
Shaula is the namesake of a character in ''Re:Zero'', a Japanese web/light novel series by Tappei Nagatsuki.
==References== {{Reflist|refs=
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<ref name=tycho2>{{cite journal |last1=Høg |first1=E. |last2=Fabricius |first2=C. |last3=Makarov |first3=V. V. |last4=Urban |first4=S. |last5=Corbin |first5=T. |last6=Wycoff |first6=G. |last7=Bastian |first7=U. |last8=Schwekendiek |first8=P. |last9=Wicenec |first9=A. |title=The Tycho-2 catalogue of the 2.5 million brightest stars |journal=Astronomy and Astrophysics |date=2000 |volume=355 |bibcode=2000A&A...355L..27H }}</ref>
<ref name=tango>{{cite journal | bibcode=2006MNRAS.370..884T | title=Orbital elements, masses and distance of λ Scorpii a and B determined with the Sydney University Stellar Interferometer and high-resolution spectroscopy | journal=Monthly Notices of the Royal Astronomical Society|volume=370|issue=2|pages=884–890 | last1=Tango|first1=W. J.|last2=Davis|first2=J.|last3=Ireland|first3=M. J. | last4=Aerts|first4=C.|last5=Uytterhoeven|first5=K.|last6=Jacob|first6=A. P.|last7=Mendez|first7=A. | last8=North|first8=J. R.|author9-link=Eugene Seneta|last9=Seneta|first9=E. B.|last10=Tuthill|first10=P. G.|year=2006 | doi=10.1111/j.1365-2966.2006.10526.x| doi-access=free |arxiv = astro-ph/0605311 |s2cid=13971499}}</ref>
<ref name=stanbridge>{{cite journal|bibcode=1857PPIVT...2..137S|title=On the astronomy and mythology of the Aborigines of Victoria|journal=Proceedings of the Philosophical Institute of Victoria|volume=2|pages=137|last1=Stanbridge|first1=William Edward|year=1857}}</ref>
<ref name=hamacher>{{cite journal | last1 = Hamacher | first1 = Duane W. | last2 = Frew | first2 = David J. | date = 2010 | title = An Aboriginal Australian Record of the Great Eruption of Eta Carinae | journal = Journal of Astronomical History and Heritage | volume = 13 | issue = 3 | pages = 220–34 | doi = 10.3724/SP.J.1440-2807.2010.03.06 | arxiv = 1010.4610 | bibcode = 2010JAHH...13..220H| s2cid = 118454721 }}</ref>
<ref name=Burnham>{{cite book | author=Robert Burnham | title=Burnham's Celestial Handbook: An Observer's Guide to the Universe Beyond the Solar System | url=https://books.google.com/books?id=PJzIt3SIlkUC|year=1978|publisher=Courier Corporation | location=New York|isbn=978-0-486-23673-5|page=1678}}</ref>
<ref name=Rogers>{{cite journal | last=Rogers | first=J. H. | title=Origins of the ancient constellations: I. The Mesopotamian traditions | journal=Journal of the British Astronomical Association |issue=1 | volume=108 | pages=9–28 |date=February 1998 | bibcode=1998JBAA..108....9R}}</ref>
<ref name=chinengstars>{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm 香港太空館 - 研究資源 - 亮星中英對照表] {{webarchive|url=https://web.archive.org/web/20081025110153/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm |date=2008-10-25 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref>
<ref name=zh>{{in lang|zh}} ''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}}.</ref>
<ref name="WGSN1">{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf | title=Bulletin of the IAU Working Group on Star Names, No. 1 |accessdate=28 July 2016}}</ref>
<ref name="WGSN">{{cite web | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN) | accessdate=22 May 2016 | archive-date=15 July 2018 | archive-url=https://web.archive.org/web/20180715111556/https://www.iau.org/science/scientific_bodies/working_groups/280/ | url-status=dead }}</ref>
<ref name=MAST>{{cite web |title=MAST: Barbara A. Mikulski Archive for Space Telescopes |url=https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html |publisher=Space Telescope Science Institute |access-date=8 December 2021}}</ref>
<ref name=hipparcos>{{cite journal|bibcode=2007A&A...474..653V|title=Validation of the new Hipparcos reduction|journal=Astronomy and Astrophysics|volume=474|issue=2|pages=653–664|last1=Van Leeuwen|first1=F.|year=2007|doi=10.1051/0004-6361:20078357|arxiv = 0708.1752 |s2cid=18759600}}</ref>
<ref name=hamdy>{{cite journal|bibcode= 1993Ap&SS.203...53H|title= A catalogue of spectral classification and photometric data of B-type stars|journal= Astrophysics and Space Science|volume= 203|pages= 53–107|last1= Hamdy|first1= M. A.|last2= Abo Elazm|first2= M. S.|last3= Saad|first3= S. M.|year= 1993|issue= 1|doi= 10.1007/BF00659414|s2cid= 122459090}}</ref>
<ref name=Gontcharov2006>{{cite journal|bibcode=2006AstL...32..759G|title=Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system|journal=Astronomy Letters|volume=32|issue=11|pages=759–771|last1=Gontcharov|first1=G. A.|year=2006|doi=10.1134/S1063773706110065|arxiv = 1606.08053 |s2cid=119231169}}</ref>
<ref name=balona>{{cite journal|bibcode=1975MNRAS.172..191B|title=The luminosities of the beta Canis Majoris variables, the zero age main sequence and the distance of the Sco-Cen association|journal=Monthly Notices of the Royal Astronomical Society|volume=172|pages=191–203|last1=Balona|first1=L. A.|last2=Feast|first2=M. W.|year=1975|issue=1 |doi=10.1093/mnras/172.1.191|doi-access=free}}</ref>
<ref name=handler>{{cite journal|bibcode=2013A&A...557A...1H|title=Time-resolved multicolour photometry of bright B-type variable stars in Scorpius|journal=Astronomy & Astrophysics|volume=557|pages=A1|last1=Handler|first1=G.|last2=Schwarzenberg-Czerny|first2=A.|year=2013|doi=10.1051/0004-6361/201321886|arxiv = 1307.2733 |s2cid=56403146}}</ref>
<ref name=variability>{{cite journal|doi=10.1051/0004-6361:20041223 | bibcode=2004A&A...427..581U | volume=427 | issue=2 | title=Interpretation of the variability of the β Cephei star λ Scorpii | journal=Astronomy and Astrophysics | pages=581–592| year=2004 | last1=Uytterhoeven | first1=K. | last2=Willems | first2=B. | last3=Lefever | first3=K. | last4=Aerts | first4=C. | last5=Telting | first5=J. H. | last6=Kolb | first6=U. | doi-access=free | hdl=2066/60554 | hdl-access=free }}</ref>
<ref name=Kunitzsch>{{cite book |last1=Kunitzsch |first1=Paul |last2=Smart |first2=Tim |date = 2006 |edition = 2nd rev. |title = A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations |publisher = Sky Pub |location = Cambridge, Massachusetts |isbn = 978-1-931559-44-7 }}</ref>
<ref name="IAU-CSN">{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |accessdate=28 July 2016}}</ref>
<ref name=vsx>{{cite web |url=https://vsx.aavso.org/index.php?view=detail.top&oid=34006 |title=Lambda Sco |website=International Variable Star Index |publisher=AAVSO |access-date=2025-08-20 }}</ref>
<ref name="ASE">{{cite web |title=Mula |url=https://ase.exopla.net/index.php/Mula |website=All Skies Encyclopaedia |publisher=IAU Working Group on Star Names |access-date=20 August 2025}}</ref>
}}
{{Stars of Scorpius}} {{Sky|17|33|36.520|-|37|06|13.76}}
<!-- Proeprties --> Category:B-type subgiants Category:Beta Cephei variables 5 <!-- Position/catalogues --> Category:Scorpius Scorpii, Lambda 6527 Category:Durchmusterung objects Scorpii, 35 158926 085927 Shaula Category:Brightest stars