View source for Astronomy:S Doradus

{{Short description|Star in the Large Magellanic Cloud}}
{{Starbox begin
| name = S Doradus
}}
{{Starbox image
|image=[[File:Eso9931d.jpg|280px]]
|caption=S Doradus is the brightest individual star in [[Astronomy:NGC 1910|NGC 1910]], encircled by the lower "spiral arm". The bright star within the lower right nebulosity ([[Astronomy:N119|N119]]) is [[Astronomy:R85|R85]].
|credit=ESO
}}
{{Starbox observe
| epoch    = J2000
| constell = [[Astronomy:Dorado|Dorado]]
| ra       = {{RA|05|18|14.3572}}<ref name=dr2/>
| dec      = {{DEC|-69|15|01.148}}<ref name=dr2/>
| appmag_v = 8.6 – 11.5<ref name=GCVS/>
}}
{{Starbox character
| class    = B8/9eq – F0/5:Iae<ref name=mk/>
| b-v      = +0.11<ref name=nicolet/>
| u-b      = –0.98<ref name=nicolet/>
| variable = [[Astronomy:Luminous blue variable|S Doradus]]<ref name=GCVS/>
}}
{{Starbox astrometry
| radial_v = +228<ref name=rgcrv/>
| prop_mo_ra  = 1.735<ref name=dr2/>
| prop_mo_dec = 0.280<ref name=dr2/>
| parallax = 0.0073
| p_error  = 0.0371
| parallax_footnote = <ref name=dr2/>
| dist_ly  = 169,000
| dist_pc  = 51,800
| absmag_v = {{nowrap|–7.6 (1965)}}<br/>–10.0 (1989)<ref name=vangenderen2001/>
}}
{{Starbox detail
| mass     = {{val|24|16|2}}<ref name=lamers1998/>
| rotational_velocity =
| metal_fe =
| age_gyr  =
}}
{{Starbox detail|no_heading=y
| component1 = 1989 (maximum)
| radius   = 380<ref name="lamers1995"/>
| luminosity  = 910,000<ref name=vangenderen2001/>
| temperature = 8,500<ref name=vangenderen2001/>
| gravity  = 0.6<ref name="lamers1995"/>
}}
{{Starbox detail|no_heading=y
| component1 = 1985 (minimum)
| radius   = 100<ref name="lamers1995"/>
| luminosity  = 1,400,000<ref name="lamers1995"/>
| temperature = 20,000<ref name="lamers1995"/>
| gravity  = 1.6<ref name="lamers1995"/>
}}
{{Starbox detail|no_heading=y
| component1 = 1965 (deep minimum)
| radius   =
| luminosity  = 2,000,000<ref name=vangenderen2001/>
| temperature = 35,000<ref name=vangenderen2001/>
| gravity  =
}}
{{Starbox catalog
| names = [[Astronomy:Durchmusterung|CD]]-69&nbsp;295, HD&nbsp;35343, [[Astronomy:Durchmusterung|CPD]]-69&nbsp;356, [[Astronomy:IRAS|IRAS]]&nbsp;05182-6918, AAVSO&nbsp;0518-69.
}}
{{Starbox reference
| Simbad=S+Doradus
}}
{{Starbox end
}}
'''S Doradus''' (also known as '''S Dor''') is one of the brightest [[Astronomy:Star|star]]s in the [[Astronomy:Large Magellanic Cloud|Large Magellanic Cloud]] (LMC), a [[Astronomy:Satellite galaxy|satellite galaxy]] of the [[Astronomy:Milky Way|Milky Way]], located roughly 160,000 [[Astronomy:Light-year|light-year]]s away. The star is a [[Astronomy:Luminous blue variable|luminous blue variable]], and one of the [[Astronomy:List of most luminous stars|most luminous stars known]], having a luminosity varying widely above and below 1,000,000 times the luminosity of the [[Astronomy:Sun|Sun]], although it is too far away to be seen with the naked eye.

==History==
S Doradus was noted in 1897 as an unusual and variable star, of Secchi type I with bright lines of H<sub>α</sub>, H<sub>β</sub>, and H<sub>γ</sub>.<ref name=pickering/> The formal recognition as a variable star came the assignment of the name S Doradus in 1904 in the second supplement to Catalogue of Variable Stars.<ref name=hv/>

S Dor was observed many times over the coming decades. In 1924, it was described as "P Cygni class" and recorded at photographic magnitude 9.5<ref name=cannon/> In 1925, its absolute magnitude was estimated at −8.9.<ref name=shapley/> In 1933 it was listed as a 9th-magnitude Beq star with bright hydrogen lines.<ref name=merrill/> It was the most luminous star known at that time.<ref name=shapley1931/><ref name=lewis/>

In 1943, the variability was interpreted as being due to eclipses of a binary companion, orbiting with a period of 40 years.<ref name=gaposchkin/> This was refuted in 1956, when the variability was described as irregular and the spectrum as A0 with P Cygni profiles and emission for many spectral lines. The brightness was observed to decline by 0.8 magnitude from 1954 into 1955.<ref name=wesselink/> At the same time, S Doradus was noted as being similar to the Hubble–Sandage variables, the LBVs discovered in [[Astronomy:Andromeda Galaxy|M31]] and [[Astronomy:Triangulum Galaxy|M33]].<ref name=smith/> The brief 1955 minimum was followed by a deep minimum in 1964, when the spectrum was compared to [[Astronomy:Eta Carinae|Eta Carinae]] in strong contrast to the mid-A spectrum at normal brightness.<ref name=thackeray1965/>

By 1969 the nature of S Doradus was still uncertain, considered possibly to be a pre-main-sequence star,<ref name=martini/> but during the next decade the consensus settled on the S Doradus type variables and Hubble-Sandage variables being evolved massive supergiants.<ref name=thackeray1974/><ref name=sharov/> They were eventually given the name "luminous blue variables" in 1984, coined in part because of the similarity of the acronym LBV to the well-defined LPV class of variable stars.<ref name=conti/> The classification system defined for the [[Astronomy:General Catalogue of Variable Stars|General Catalogue of Variable Stars]] pre-dated this and so the acronym SDOR is used for LBVs.<ref name=kholopov/>

==Surroundings==
[[File:Eso1021d.jpg|thumb|left|upright=1.0|Large Magellanic Cloud. NGC 1910 is labelled near the centre of the image, and S Doradus is clearly visible at full size. (Credit: Robert Gendler/ESO)]]
S Doradus is the brightest member of the open cluster [[Astronomy:NGC 1910|NGC 1910]], also known as the LH41 stellar association, visible in binoculars as a bright condensation within the main bar of the LMC. This is within the [[Astronomy:N119|N119]] [[Astronomy:Emission nebula|emission nebula]], which has a distinctive spiral shape.<ref name="NeugentMassey2012"/> It is one of the visually brightest individual stars in the LMC, at some times the brightest.<ref name=massey/> There are only a handful of other 9th-magnitude stars in the LMC, such as the [[Astronomy:Yellow hypergiant|yellow hypergiant]] [[Astronomy:HD 33579|HD 33579]].<ref name=feast/>

There are several compact clusters near S Doradus, within the general NGC 1910/LH41 association. The closest is less than four arc-minutes away, contains two out of the three WO stars in the entire LMC, and the entire cluster is about the same brightness as S Doradus. A little further away is NGC 1916. Another LBV, [[Astronomy:R85|R85]], is just two arc-minutes away. This rich star-forming region also hosts a third [[Astronomy:Wolf–Rayet star|Wolf–Rayet star]], at least ten other [[Astronomy:Supergiant|supergiant]]s, and at least ten class O stars.<ref name=neugent/>

S Doradus has a number of close companion stars. The [[Astronomy:Washington Double Star Catalog|Washington Double Star Catalog]] lists two 11th-magnitude stars 5″ away, which at the distance of the LMC is about four light years.<ref name=wds/> A much closer companion has been found using the [[Astronomy:Hubble Space Telescope|Hubble Space Telescope]] [[Astronomy:Fine Guidance Sensor (HST)|Fine Guidance Sensor]], 1.7″ away and four magnitudes fainter.<ref name=aldoretta/> There are other nearby stars, most notably a 12th-magnitude OB supergiant at 13″.<ref name=wolf/>

==Variability==
[[File:SDoradus light curve long.png|thumb|left|upright=1.2|Light curve of S Doradus from 1987 to 2016, showing slow variations with a deep minimum in 2011]]
This star belongs to its own eponymous S Doradus class of variable stars, also designated as [[Astronomy:Luminous blue variable|luminous blue variable]]s or LBVs. LBVs exhibit long slow changes in brightness, punctuated by occasional outbursts. S Doradus is typically a magnitude 9 star, varying by a few tenths of a magnitude on timescales of a few months, superimposed on variations of about a magnitude taking several years. The extreme range of these variations is from about visual magnitude 8.6–10.4. Every few decades it shows a more dramatic decrease in brightness, to as low as magnitude 11.5. The nature of the variation is somewhat unusual for an LBV; S Doradus is typically in an outburst state, with only occasional fades to the quiescent state that is typical of most stars in the class.<ref name=vangenderen1997/>

[[File:SDoradus light curve short.png|thumb|right|upright=1.2|Light curve of S Doradus from 2012 to 2016, showing the microvariations superimposed on a slow rise from the deep 2011 minimum]]
The colour of S Doradus changes as its brightness varies, being bluest when the star is faintest.<ref name="lamers1995"/> At the same time, the spectrum shows dramatic changes. It is typically an extreme mid-A supergiant with P Cygni profiles on many lines (e.g. A5eq<ref name=thackeray1965/> or A2/3Ia<sup>+</sup>e<ref name=munari/>). At maximum brightness, the spectrum can become as cool as an F supergiant, with strong ionised metal lines and almost no emission components.<ref name=massey/> At minimum brightness, the spectrum is dominated by emission, particularly forbidden lines of Fe{{smallcaps|ii}} but also helium and other metals. At the deep minima these features are even more pronounced, and Fe{{smallcaps|iii}} emission also appears.<ref name=thackeray1965/>

Attempts to identify regularity in the unpredictable changes of brightness suggest a period of around 100 days for the small amplitude variations near maximum brightness. At minimum brightness, these ''microvariations'' are considered to occur with periods as long as 195 days. The slower variations have been characterised with a period of 6.8 years, with an interval of 35–40 years between deep minima. The microvariations are similar to the brightness changes shown by α Cygni variables, which are less luminous hot supergiants.<ref name=vangenderen2001/>

==The instability strip==
[[File:Lbvstar.png|thumb|left|upright=1.4|The S Doradus Instability strip and outburst region in the H–R diagram, showing S Doradus at minimum and maximum under the assumption of constant luminosity]]
S Doradus variables (LBVs) show distinct quiescent and outburst states. During the quiescent phase, LBVs lie along a diagonal band in the H–R diagram called the ''S Doradus Instability Strip'', with the more luminous examples having hotter temperatures.<ref name=wolf1989/>

The standard theory is that LBV outbursts occur when the mass loss increases and an extremely dense [[Astronomy:Stellar wind|stellar wind]] creates a pseudo-photosphere. The temperature drops until the wind opacity starts to decrease, meaning all LBV outbursts reach a temperature around 8,000–9,000 K. The bolometric luminosity during outbursts is considered to remain largely unchanged, but the visual luminosity increases as radiation shifts from the [[Physics:Ultraviolet|ultraviolet]] into the visual range.<ref name=lamers/> Detailed investigations have shown that some LBVs appear to change luminosity from minimum to maximum. S Doradus has been calculated to be less luminous at maximum brightness (minimum temperature), possibly as a result of potential energy going into expansion of a substantial portion of the star. [[Astronomy:AG Carinae|AG Carinae]] and [[Astronomy:HR Carinae|HR Carinae]] show similar luminosity decreases in some studies, but in the most convincing case AFGL 2298 increased its luminosity during its outbursts.<ref name="lamers1995"/>

Rare larger eruptions can appear as long-lasting under-luminous [[Astronomy:Supernova|supernova]]e, and have been termed [[Astronomy:Supernova impostor|supernova impostor]]s. The cause of the eruptions is unknown, but the star survives and may experience multiple eruptions. Eta Carinae and P Cygni are the only known examples in the Milky Way, and S Doradus has not shown such an eruption.<ref name=davidson/>

==Stellar properties==
[[File:Lbv-sdoradus.png|thumb|right|upright=1.4|S Doradus properties at minimum and maximum according to different studies:
<br/>- van Genderen (2001),<ref name=vangenderen2001/> temperature at minimum derived from colour index
<br/>- Lamers (1995),<ref name=lamers1995/> properties derived from non-LTE model atmosphere
<br/>- Humphreys & Davidson (1994),<ref name=humphreys1994/> temperature at minimum assumes constant luminosity]]
The temperature of an LBV is difficult to determine because the spectra are so peculiar and the standard colour calibrations don't apply, so the luminosity changes associated with brightness variations cannot be calculated accurately. Within the margins of error, it has often been assumed that the luminosity stays constant during all LBV outbursts. This is likely if the outburst consists only of an opaque stellar wind forming a pseudo-photosphere to mimic a larger cooler star.<ref name=smithvink/>

Better atmospheric physics and observations of luminosity changes during some LBV outbursts have cast doubt on the original models.<ref name=smith2015/> The atmosphere of S Doradus has been modeled in detail between a normal minimum at magnitude 10.2 in 1985 and a maximum at magnitude 9.0 in 1989. The temperature was calculated to drop from 20,000 K to 9,000 K, and the luminosity dropped from {{solar luminosity|1,400,000}} to {{solar luminosity|708,000}}. This corresponds to an increase in the radius of the visible surface of the star from {{solar radius|100}} to {{solar radius|380}}.<ref name="lamers1995"/> A simpler calculation of the variation from the deep 1965 minimum at magnitude 11.5 to the 1989 maximum gives a temperature drop from 35,000 K to 8,500 K, and the luminosity drop from {{solar luminosity|2,000,000}} to {{solar luminosity|910,000}}.<ref name=vangenderen2001/> For a brief period during the maximum in late 1999, the temperature dropped further to between 7,500 K and 8,500 K, without the brightness changing noticeably. This is normal in other LBVs at maximum and is as cool as they can get, but it has not been seen in S Doradus before, or since.<ref name=massey/> Observations of AG Carinae have shown that any luminosity changes between minimum and maximum may occur abruptly over a small temperature range, with the luminosity approximately constant during the rest of the light curve.<ref name=groh/>

The mass of an LBV is difficult to calculate directly unless it is in a binary system. The surface gravity changes dramatically and is difficult to measure from the peculiar spectral lines, and the radius is poorly defined. LBVs are thought to be the direct predecessors of [[Astronomy:Wolf–Rayet star|Wolf–Rayet star]]s, but may be either just evolved from the main sequence or post-[[Astronomy:Red supergiant|red supergiant]] stars with much lower masses. In the case of S Doradus, the current mass is likely to be in the range of {{solar mass|20–45}}.<ref name=lamers1998/><ref name="lamers1995"/>

==References==
{{reflist|30em|refs=

<ref name=dr2>{{cite DR2|4658193814095915776}}</ref>

<ref name=GCVS>{{cite journal|bibcode=2009yCat....102025S|title=VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007–2013)|journal=VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S|volume=1|pages=02025|last1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|year=2009|display-authors=0}}</ref>

<ref name="lamers1995">{{cite conference | last=Lamers | first=H. J. G. L. M. | contribution=Observations and Interpretation of Luminous Blue Variables | title=Proceedings of IAU Colloquium 155, Astrophysical applications of stellar pulsation | journal=Astrophysical Applications of Stellar Pulsation. Astronomical Society of the Pacific Conference Series | volume=83 | pages=176–191 | date=February 6–10, 1995 | location=Cape Town, South Africa | publisher=Astronomical Society of the Pacific | bibcode=1995ASPC...83..176L }}</ref>

<ref name=lamers1998>{{cite journal|bibcode=1998A&A...335..605L|title=Periods, period changes and the nature of the microvariations of Luminous Blue Variables|journal=Astronomy and Astrophysics|volume=335|pages=605|last1=Lamers|first1=H. J. G. L. M.|last2=Bastiaanse|first2=M. V.|last3=Aerts|first3=C.|last4=Spoon|first4=H. W. W.|year=1998}}</ref>

<ref name=rgcrv>{{cite conference | last=Evans | first=D. S. | date=June 20–24, 1966 | editor1-last=Batten | editor1-first=Alan Henry | editor2-last=Heard | editor2-first=John Frederick | title=The Revision of the General Catalogue of Radial Velocities | book-title=Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30 | location=University of Toronto | publisher=International Astronomical Union | bibcode=1967IAUS...30...57E }}</ref>

<ref name=nicolet>{{cite journal | last1=Nicolet | first1=B. | year=1978 | title=Photoelectric photometric Catalogue of homogeneous measurements in the UBV System | journal=Astronomy and Astrophysics Supplement Series | volume=34 | pages=1–49 | bibcode=1978A&AS...34....1N }}</ref>

<ref name=massey>{{cite journal | last1=Massey | first1=Philip | title=An Unprecedented Change in the Spectrum of S Doradus: As Cool as It Gets | journal=The Publications of the Astronomical Society of the Pacific | volume=112 | issue=768 | pages=144–147 |date=February 2000 | doi=10.1086/316515 | bibcode=2000PASP..112..144M | doi-access=free }}</ref>

<ref name=vangenderen2001>{{cite journal |last1=van Genderen |first1=A.M. |date=2001 |title=S Doradus variables in the Galaxy and the Magellanic Clouds |journal=Astronomy & Astrophysics | volume=366 |issue=2 |pages=508–531 |bibcode=2001A&A...366..508V |doi=10.1051/0004-6361:20000022|doi-access=free }}</ref>

<ref name="NeugentMassey2012">{{cite journal|last1=Neugent|first1=Kathryn F.|last2=Massey|first2=Philip|last3=Morrell|first3=Nidia|title=The Discovery of a Rare Wo-Type Wolf–Rayet Star in the Large Magellanic Cloud|journal=The Astronomical Journal|volume=144|issue=6|year=2012|pages=162|issn=0004-6256|doi=10.1088/0004-6256/144/6/162|bibcode=2012AJ....144..162N|arxiv = 1210.0062 |s2cid=118628394}}</ref>

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<ref name=aldoretta>{{cite journal|bibcode= 2015AJ....149...26A|title= The Multiplicity of Massive Stars: A High Angular Resolution Survey with the Guidance Sensor|journal= The Astronomical Journal|volume= 149|issue= 1|pages= 26|last1= Aldoretta|first1= E. J.|last2= Caballero-Nieves|first2= S. M.|last3= Gies|first3= D. R.|last4= Nelan|first4= E. P.|last5= Wallace|first5= D. J.|last6= Hartkopf|first6= W. I.|last7= Henry|first7= T. J.|last8= Jao|first8= W.-C.|last9= Maíz Apellániz|first9= J.|last10= Mason|first10= B. D.|last11= Moffat|first11= A. F. J.|last12= Norris|first12= R. P.|last13= Richardson|first13= N. D.|last14= Williams|first14= S. J.|year= 2015|doi= 10.1088/0004-6256/149/1/26|arxiv = 1410.0021 |s2cid= 58911264}}</ref>

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<ref name=wolf>{{cite journal|bibcode=1980A&A....88...15W|title=IUE and ground based observations of the LMC star S Doradus|journal=Astronomy and Astrophysics|volume=88|pages=15|last1=Wolf|first1=B.|last2=Appenzeller|first2=I.|last3=Cassatella|first3=A.|year=1980}}</ref>

<ref name=pickering>{{cite journal|bibcode=1897ApJ.....6..459P|title=Large Magellanic Cloud|journal=Astrophysical Journal|volume=6|pages=459|last1=Pickering|first1=E. C.|last2=Fleming|first2=W. P.|year=1897|doi=10.1086/140426}}</ref>

<ref name=hv>{{cite journal|bibcode=1905AnHar..53..143P|title=Second supplement to Catalogue of Variable Stars|journal=Annals of Harvard College Observatory|volume=53|pages=143|last1=Pickering|first1=Edward C.|year=1905}}</ref>

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<ref name=shapley>{{cite journal|bibcode=1925HarCi.271....1S|title=The Magellanic Clouds, IV. The Absolute Magnitudes of Nebulae, Clusters, and Peculiar Stars in the Large Cloud|journal=Harvard College Observatory Circular|volume=271|pages=1|last1=Shapley|first1=Harlow|last2=Wilson|first2=Harvia H.|year=1925}}</ref>

<ref name=merrill>{{cite journal|bibcode=1933ApJ....78...87M|title=Catalogue and Bibliography of Stars of Classes B and a whose Spectra have Bright Hydrogen Lines|journal=Astrophysical Journal|volume=78|pages=87|last1=Merrill|first1=Paul W.|last2=Burwell|first2=Cora G.|year=1933|doi=10.1086/143490|doi-access=free}}</ref>

<ref name=shapley1931>{{cite journal|bibcode=1931BHarO.881....1S|title=Notes on the Large Magellanic Cloud, I. A Cosmographic Survey|journal=Harvard College Observatory Bulletin |volume=881|pages=1|last1=Shapley|first1=Harlow|year=1931}}</ref>

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<ref name=gaposchkin>{{cite journal|bibcode=1943ApJ....97..166G|title=The Variable Star S Doradus as an Eclipsing Binary|journal=Astrophysical Journal|volume=97|pages=166|last1=Gaposchkin|first1=Sergei|year=1943|doi=10.1086/144509|doi-access=free}}</ref>

<ref name=wesselink>{{cite journal|bibcode=1956MNRAS.116....3W|title=Spectroscopic and photometric observations of S Doradus|journal=Monthly Notices of the Royal Astronomical Society|volume=116|pages=3–9|last1=Wesselink|first1=A. J.|year=1956|doi=10.1093/mnras/116.1.3|doi-access=free}}</ref>

<ref name=smith>{{cite journal|bibcode=1957PASP...69..137S|title=Spectra of Bright-Line Stars in the Large Magellanic Cloud|journal=Publications of the Astronomical Society of the Pacific|volume=69|issue=407|pages=137|last1=Smith|first1=Henry J.|year=1957|doi=10.1086/127032|doi-access=free}}</ref>

<ref name=thackeray1965>{{cite journal|bibcode=1965MNRAS.129..169T|title=Spectroscopic variations of S. Doradus|journal=Monthly Notices of the Royal Astronomical Society|volume=129|issue=2|pages=169–180|last1=Thackeray|first1=A. D.|year=1965|doi=10.1093/mnras/129.2.169|doi-access=free}}</ref>

<ref name=martini>{{cite journal|bibcode=1969A&A.....3..443M|title=On the interpretation of S Doradus|journal=Astronomy and Astrophysics|volume=3|pages=443|last1=Martini|first1=A.|year=1969}}</ref>

<ref name=thackeray1974>{{cite journal|bibcode=1974MNRAS.168..221T|title=Variations of S Dor and HDE 269006|journal=Monthly Notices of the Royal Astronomical Society|volume=168|pages=221–233|last1=Thackeray|first1=A. D.|year=1974|doi=10.1093/mnras/168.1.221|doi-access=free}}</ref>

<ref name=sharov>{{cite book|bibcode=1975IAUS...67..275S|chapter=S Dor-type variables in other galaxies|series=Proceedings of the International Astronomical Union Symposia|volume=67|pages=275–284|last1=Sharov|first1=A. S.|title=Variable Stars and Stellar Evolution|year=1975|doi=10.1007/978-94-010-9934-9_38|isbn=978-90-277-0579-2}}</ref>

<ref name=conti>{{cite book|bibcode=1984IAUS..105..233C|chapter=Basic Observational Constraints on the Evolution of Massive Stars|series=Proceedings of the International Astronomical Union Symposia|volume=105|pages=233–254|last1=Conti|first1=P. S.|title=Observational Tests of the Stellar Evolution Theory|year=1984|doi=10.1007/978-94-010-9570-9_47|isbn=978-90-277-1775-7}}</ref>

<ref name=kholopov>{{cite journal|bibcode=1981PZ.....21..465K|title=On the Classification of Variable Stars|journal=Peremennye Zvezdy|volume=21|pages=465|last1=Kholopov|first1=P. N.|year=1981}}</ref>

<ref name=wolf1989>{{cite book|doi=10.1007/978-94-009-1031-7_10|chapter="Normal" LBV Eruptions a La S Doradus|title=Physics of Luminous Blue Variables|volume=157|pages=91–100|series=Astrophysics and Space Science Library|year=1989|last1=Wolf|first1=B.|isbn=978-94-010-6955-7}}</ref>

<ref name=lamers>{{cite book|doi=10.1007/978-94-009-3901-1_7|chapter=Variations in Luminous Blue Variables|title=Instabilities in Luminous Early Type Stars|volume=136|pages=99–126|series=Astrophysics and Space Science Library|year=1987|last1=Lamers|first1=Henny J. G. L. M.|isbn=978-94-010-8232-7}}</ref>

<ref name=davidson>{{cite book|doi=10.1007/978-94-009-3901-1_8|chapter=Giant Outbursts of the Eta Carinae – P Cygni Type|title=Instabilities in Luminous Early Type Stars|volume=136|pages=127–142|series=Astrophysics and Space Science Library|year=1987|last1=Davidson|first1=Kris|isbn=978-94-010-8232-7}}</ref>

<ref name=vangenderen1997>{{cite journal|bibcode=1997A&A...318...81V|title=New discoveries on the S DOR phenomenon based on an investigation of the photometric history of the variables AG Car, S DOR and Eta Car|journal=Astronomy and Astrophysics|volume=318|pages=81|last1=Van Genderen|first1=A. M.|last2=Sterken|first2=C.|last3=De Groot|first3=M.|year=1997}}</ref>

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<ref name=neugent>{{cite journal|bibcode=2012AJ....144..162N|arxiv=1210.0062|title=The Discovery of a Rare WO-type Wolf-Rayet Star in the Large Magellanic Cloud|journal=The Astronomical Journal|volume=144|issue=6|pages=162|last1=Neugent|first1=Kathryn F.|last2=Massey|first2=Philip|last3=Morrell|first3=Nidia|year=2012|doi=10.1088/0004-6256/144/6/162|s2cid=118628394}}</ref>
}}

==External links==
* http://www.daviddarling.info/encyclopedia/S/S_Doradus.html
* http://jumk.de/astronomie/big-stars/s-doradus.shtml

{{Stars of Dorado}}


{{DEFAULTSORT:S Doradus}}
[[Category:Stars in the Large Magellanic Cloud]]
[[Category:Emission-line stars]]
[[Category:Henry Draper Catalogue objects|035343]]
[[Category:Large Magellanic Cloud]]
[[Category:Luminous blue variables]]
[[Category:Extragalactic stars]]
[[Category:Objects with variable star designations|Doradus, S]]
[[Category:Durchmusterung objects]]

{{Sourceattribution|S Doradus}}