Revista Mexicana de Astronomía y Astrofísica ISSN: 0185-1101 [email protected] Instituto de Astronomía México

Corcoran, M. F. ETA CARINAE AND OTHER LUMINOUS BLUE VARIABLES Revista Mexicana de Astronomía y Astrofísica, vol. 33, 2008, pp. 123-128 Instituto de Astronomía Distrito Federal, México

Available in: http://www.redalyc.org/articulo.oa?id=57116159043

How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative © 2008: Instituto de Astronomía, UNAM - Massive Stars: Fundamental Parameters and Circumstellar Interactions Ed. Paula Benaglia, Guillermo Bosch, & Cristina Cappa a VsEaCrneyH 30 uioa nrysX oocsstestigo. casos como X, rayos caracter´ en las luminosas y 5380, HD duplicidad, y la Carinae jugar Eta aqu´ puede LVBs ingl´ discute que las en Se rol nombre el escala. su objetos, gran (por a y luminosas inestable l´ azules al variables cercanas masivas, las extremadamente que cree Se SC rebl,M 07,UA([email protected]. USA nasa.gov). 20771, MD Greenbelt, GSFC, eMxA(ei eConferencias) de (Serie RevMexAA ice ut 0 ouba D204 USA. 21044, MD Columbia, 500 Suite Circle, otesproaepoini l u h otmas- most the but prior all material in winds of explosion Stellar share supernova lion’s the loss. to the mass off drive all: certainly of problem damental few fields. are magnetic there but which explanations for alternative signatures good X-ray hard or ric and ii n ec rn obuso ag-cl,usal asls.Idsuscretudrtnigo the these of of understanding cases. characteristics test current physical as discuss known 5980 and I HD play and Carinae may loss. Eta Eddington duplicity mass LBVs the role unstable luminous to X-ray the large-scale, close the objects, stars of using massive these stars bouts extremely of to evolved, state prone be evolutionary to hence believed and are Limit (LBVs) Variables Blue Luminous ancaso o tr (like cer- a stars of hot recognition of the class problem. difficult been tain classic, has a breakthrough course of A is detection observational fields The such means of them. numerous create to has hand collapse, astronomer at protostellar resilient the the left from simply then intensified not are and of fields matter massiveover these a That If longer no controversy. is much fields interior. magnetic stellar possess magnetic stars the understood de- threading poorly largely as-yet field itself the is on angu- which of pendent process loss a and momentum, exchange lar through coupled intrin- evolution sically core-envelope a of into problem morphed combined has calamity impending this of un- aware blissfully envelope a by non-magnetic surrounded inert, catastrophe relatively iron burning the merrily to down furnace way nuclear its core old, a The of idea astrophysics. simple modern in problems complex e Words: Key 1 2 n ehvntee etoe h otfun- most the mentioned even haven’t we And h vlto fmsiesasi n ftemost the of one is stars massive of evolution The RSTadXryAtohsc aoaoyNASA/ Laboratory Astrophysics X-ray and CRESST nvriisSaeRsac soito,121Wincopin 10211 Association, Research Space Universities τ c)wihso aibespectropolarimet- variable show which Sco) T AIA N TE UIOSBU VARIABLES BLUE LUMINOUS OTHER AND CARINAE ETA iais eea tr:erytp tr:eouin—sas niiul(t aia)—sas mass stars: — Carinae) (Eta individual stars: — evolution stars: — early-type stars: — general binaries: os—xry:stars x-rays: — loss .INTRODUCTION 1. θ 1 r ,H 191612, HD C, Ori , 33 mt eEdntn o oqeeprmna p´ experimentan que lo por Eddington, de ımite 2–2 (2008) 123–128 , acondici´ la ı .F Corcoran F. M. ABSTRACT RESUMEN nata e ooiinodletd vltv eestos de evolutivo estado del conocimiento del actual on rpin?adhwotnd hyocr(rrecur)? (or occur they do often such how undergo and stars a massive eruptions? which of and fate ultimate star? the massive determining in eruptions LBV and Cygni ex- P Galactic are canonical evolving The amples stars stage. massive Wolf-Rayet LBVs extremely the are to be Variable. stars to not these believed sometimes are and obvious: Blue, so not not often actually (1984) are Conti which by of Variables called layers Blue were outer objects Luminous the Such of star). 50-90% (perhaps the as material much of as outbursts removing un- giant as-yet way some specified star in & the produce (Eddington as limits Humphreys-Davidson) important produced two instabilities towards evolves this, Above 30). ihhayeeet n lc holes. Universe black early and elements the im- heavy have seeding with would on eruptions such implications so portant mode if and dominant ob- loss, the have mass III are there of ejections Population But such for perhaps long. that jects very claims because last interesting but to been supernova) seem minor don’t a they as energy much as eruptions ( these spectacular because not aren’t theoreti- much, and not mass suspect astronomers wind cians observational eruptions stellar Both LBV steady eposidic loss. (relatively) these to how in clear compared lost completely is not It’s mass presented (2005). much been al. et has Clark LBVs by Galactic of compendium ieo asv tr (10 stars massive of sive sia f´ ısticas oeqetosae o motn r these are important how are: questions Some 1,2 scscncdsd sa srla,usando estrellas, estas de conocidas ısicas s Bs o srla vlcoaa y evolucionadas estrellas son LBVs) es: η aia’ o xml released example for Carinae’s orbits a well-separated even then possibly the and not stars, tion) if massive systems be, those of to for seem majority (which least companions at close evolution, with of process the anyway? eruptions these fields? causes drive magnetic what help and And they momentum do angular mo- or in angular changes in fields? changes magnetic on and depend mentum they do how and 124 ( tysosdnesrcue jcadw o0 to down ejecta structured dense shows etry n cle odsetwa’ on ntehat of hearts the a in as going stars. acts what’s extreme How- emission dissect these X-ray to bright cases scalpel general. X-ray these fine of in in instances and LBVs particular LBVs, of are probe there ever poor a Wolf- X-ray few makes studies very This com- fact, either). collapsed of systems point emitting Rayet+collapsed in X-ray (and, We system LBV+ panion LBVs. extremely no Galactic an most of is are know Cygni as P source, example, hard X-ray For weak (unfortunately) by. are come hard sources to of such source a and need you LBV X-rays, that the is difficulty of The regions wind. innermost the in can material, probing keV) of AUprinciple columns few few enormous a of through a (above penetrate X-radiation size be Hard extended can radius). the (which in by photosphere limited free-free but the radi- useful Long-wavelength is inside. as ation conditions useful of is many probe murk in the a penetrate thick, difficult. can LBV very which the Radiation be of observation can direct making ejecta cases This eruption. ue,bplrnbl wisclykona the struc- as a known as (whimsically seen Erup- be nebula “Homunculus” “Great can bipolar which the of tured, as residue lore the event tion”, astronomical an in in became century 19th which known the star in bright brighter pc) enormously (2300 nearby atively .XRYEISO:APO RB FTHE OF PROBE POOR A EMISSION: X-RAY 2. ∼ 3 0 U rls rmtestar. the from less or AU) 200 eidcsetoercvraiiyadbroad- and variability spectrometric Periodic ulct loudutdypasamjrrl in role major a plays undoubtedly also Duplicity Bsaesrone ytedtiu ftheir of detritus the by surrounded are LBVs η A rical aedaf upsdypoue na in produced supposedly dwarf, made artificially “An aia sawl-nw aatcLV rel- a LBV; Galactic well-known a is Carinae − 0kV -a aitossrnl suggest strongly variations X-ray keV) 10 3 urudn h tr Interferom- star. the surrounding ) B PHENOMENON LBV 2.1 . η Carinae dictionary.com ;inthis . 1 nee etrdtcin huhti euti tl somewhat be still might is which result spectra, this though FUSE controversial. detection, UV better far even in an companion the of i.1 oprsno a of Comparison 1. Fig. I npriua)aesoni iue2 ln with along 2, Figure in shown are particular) in XIV measured Centroids gas. shocked the of flow bulk the of- ions, hydrogen-like and helium-like simple from (2005). Corcoran and Corcoran (2005) & al. Pittard al. et (2001), Verner et (2002), al. Hillier et from Corcoran taken 1. Table (2001), largely in are given is numbers parameters These stellar the to as guess star Wolf-Rayet a even perhaps or supergiant bright g.WP2iaecuts fN mt n .Morse. J. and Smith im- N. the of of courtesy center image the WFPC2 at age. point surrounds X-ray-bright and and nebula. extended optical- Homunculus is bipolar emission inner the X-ray The image. η of η eetdrcl.Agal h etipii detec- implicit sion best the Arguably directly. detect rmsrn ie S II&S I,adSX S & XV S and XIV, Si & XIII thus (Si and lines centroids strong from line measure to used be can spec- thermo- grating tra and transmission resolution dynamic High both gas, dynamic. shocked condi- the the of of tions diagnostics important numerous fering A wind). dense fast, sufficiently a have to order (in idwt h idof wind the with wind ino h opno struhteXryemis- X-ray the through is companion the of tion yr aia ) hseiso eursawn velocity wind a requires emission This A). Carinae aia n h ouclswt nHST/WFPC2 an with Homunculus the and Carinae − 4 ∼ h hce hra a rdcsln emission line produces gas thermal shocked The oeta pn ta.(05 lie pcrlsignature spectral a claimed (2005) al. et Iping that Note 1 4 mligta h opno ( companion the that implying , 00k s km 3000 eeae ytecliino h companion’s the of collision the by generated − 1 n asls aeo 10 of rate loss mass a and η aia o oeproperly more (or Carinae CHANDRA η η aia )i a is B) Carinae -a mg of image X-ray aia sthe is Carinae − 5 M © 2008: Instituto de Astronomía, UNAM - Massive Stars: Fundamental Parameters and Circumstellar Interactions Ed. Paula Benaglia, Guillermo Bosch, & Cristina Cappa pcrmtr(EG)setaa ucino -a yl phase cycle X-ray of apastron, function a as spectra (HETGS) Spectrometer h o hne stecmainmvsi orbit. of in moves orientation companion the the when as the sight changes of of flow the velocity line the projected along the veloci- flow by centroid dominated line are the ties in variations Significant B. of wind (slow) strong η the separates which the discontinuity”, boundary “contact the orienta- of changing geometry the and of tion phase each at model simple a of flow the (and cone of shock velocity observer. the wind the of the towards side to directed trailing more comparable the becomes becomes when cone) occur secondary the observed the along velocities of gas line velocity shocked X-ray the orbital highest the The when primary. the periastron near force Coriolis from velocities centroid line to emission relative X-ray shows graph The 2. Fig. e eid()––2024 – – (d) Period a V Mass Radius i ui.10 Lumin. T MM aia rmtewa fs)wn of wind (fast) weak the from A Carinae ◦ ˙ SIAE YTMPRMTR FOR PARAMETERS SYSTEM ESTIMATED ∞ eff U––15? – – AU Parameter ms500 km/s K1 4 – 34? 15 kK M y 10 /yr R φ η 6 =0 L a n h hp ftecnatdsotniy ihteosre otergt(ntedrcinof direction the (in right the to observer the with discontinuity, contact the of shape the and A Car . )i l h lt.Tecnatdsotniysit ihteobtlmto,adi wse ythe by twisted is and motion, orbital the with shifts discontinuity contact The plots. the all in 5) η η − AL 1 TABLE CARINAE 4 a A Car 5 0?– 20?? 150 − 03? – 30?? 90 − ––0 40 ––45 0030?– 3000? 1000 10 − 3 η 10 a System B Car . − ?– 9? 5 ?– T A N TE BS125 LBVS OTHER AND CAR ETA η . Carinae 8 − − ± 0 90 . 95 2 a ntesokfot rprasee “mini- pas- a periastron even near perhaps sage. occurring or material front, of shock ejection” the from on material might A wind variation nae of This pileup a either ends. suggest minimum maximum af- X-ray again a the and reaches ter minimum, souce brightness mate- X-ray X-ray of the the during amount of The during front in source 3). rial X-ray Figure the the (see minimum of of the front variation the in provide the density they of column results, measurement other accurate Among first et Hamaguchi by (2007). discussed al. been has state low X-ray nteSC odsmayo h ytmi avail- Naz´ is system (2004). the Koenigsberger Wolf-Rayet of A) from summary Star known able good of 12 A state SMC. the of the on in one WR depending a is 13 is (actually system B) stars The (Star other the star. while 1994, compo- erup- around LBV-type one an tion underwent Cloud, A) (Star Magellanic which of Small nent the in binary a ense namsiebnr eodteMilky the beyond binary massive a emission in X-ray seen phase-dependent been has that orbit, the time from to first phase-locked emission the and X-ray variable is the system that the shown recently have rey D58 samsie 0dyeclipsing 20-day massive, a is 5980 HD Briefly: the through spectrum X-ray the of variation The φ CHANDRA ne lt hwteoinainof orientation the show plots Inset . ihEeg rnmsinGrating Transmission Energy High 2.2 D5980 HD . ta.(2007) al. et e η η a B Car Cari- © 2008: Instituto de Astronomía, UNAM - Massive Stars: Fundamental Parameters and Circumstellar Interactions Ed. Paula Benaglia, Guillermo Bosch, & Cristina Cappa trBi nfotw’esen extra seeing we’re front in when is that lower means B the this star Rather through B). star secondary shock of at wind the density (since, emis- viewing soft expected we’re extra be eclipse, of might presence increase the which flux to sion due X-ray If simply the not sec- brightness. that is near X-ray means the peaks this with system confirmed, along the eclipse of ondary hardness X-ray the increase A. Star an from by a speed compensated wind by is the the declined loss in that has mass suggests This A in decline time. Star that from over amount though rate large even loss years, mass five the about obser- in by same separated the vations remained has eclipse) (secondary eetnl,teXrybihns tphase at brightness X-ray from lightcurve the terestingly, X-ray the obser- shows X-ray XMM the 4 of Figure interval time a the vations. about by over rate 5 loss of mass factor LBV’s the de- in strict change a rather spite seems phase-dependence The Way. aiei ht eas h ytmi ceti,it eccentric, as is increase velocities system wind pre-shock alter- the the An that because B. be may star that, must of is cone photosphere shock native the this the than of eclipsing, larger viewed part is be be hottest system to the the shock that Because means the of phase. this part at hottest allows B the star of of wind more weaker the that mean may This 2 CORCORAN 126 i.3 oundniist h -a orev.X-ray vs. triangles), source X-ray (filled by the measured to as densities phase Column 3. Fig. aeilocrigna eisrnpsae rmHam- (2007). From al. of et passage. “mini-ejection” aguchi periastron a near perhaps ma- occurring of or of front, material end pileup shock a the the either on after suggest terial maxi- might again This a and minimum. reaches minimum, the density the column during The mum triangles). (open Naz´ bevtosi h 1 the in observations ta.(07 losoe ekeiec that evidence weak showed also (2007) al. et e ASCA XMM oe ice)and circles) (open fildcircles), (filled . 5 − 0kVbn.In- band. keV 10 hard CHANDRA BeppoSAX emission. φ =0 . 36 dbl?O ore nacasa ml steclass the as draw small to as hard class it’s a LBVs, in of course, Of oddball? a l hssuyldu oadee understanding is deeper or a phenomena, to LBV us the led of study this all has ihalwrms osrt hnsa A. star companion than star rate WR a loss B, mass star lower by a A with star HD of for eclipse phase the orbital ing of function Naz´ a from as 5980, fluxes X-ray 4. Fig. msino h ytma psrn nobservation accomplished. been an X-ray yet the apastron, not view at has to system which be the would of this emission of test harder A in resulting emission. apastron, towards move stars the a ea neetn etcs fti proposition. this of case test interesting an 5980 be HD may stars. LBV SMC III-type low-primordial-metallicity Population in The role of significant evolution a the effective. play affecting so could not eruptions is giant driving metal- Such low wind by mass at stellar role suggested where LBV important licities evolu- as eruptive, especially the be, an that plays in may (2006), loss role It Owocki & major stars. Smith a massive explo- play of supernova may tion the it LBV the then before through sion) times pass multiple may vi- stars phase sufficiently mass because loss sufficient mass or If or olent, the long, because sufficiently (either it. is stage stage this through star in pass accomplished a this is to massive important loss how be how exactly to unclear or needs is, is evolution It of stage still. rarer ables asv tr r ae n uiosBu Vari- Blue Luminous and rare, are stars Massive η aia spoal h etsuidLV but LBV; studied best the probably is Carinae ta.(07.TeXryflxpasdur- peaks flux X-ray The (2007). al. et e .CONCLUSIONS 3. any η eea conclusions. general aia “gonzo” a Carinae © 2008: Instituto de Astronomía, UNAM - Massive Stars: Fundamental Parameters and Circumstellar Interactions Ed. Paula Benaglia, Guillermo Bosch, & Cristina Cappa S lue m n o el u s´ que la de flor una a lives: m´ many ama so alguien touched who —Si Virpi, of memory In then LBVs, of experience. trait ancillary an η other is the duplicity On shaping if Homunculus). in hand been the role like it’s a nebulae (and play bipolar may it duplicity to phenom- that fundamental LBV suspected is the duplicity of if understanding ena, the deeper re- points to can perhaps way it “discovered”) (if considered star be companion ally the of “discovery” The iiytmsae oee.As h ae emt cu ertesm hss ’ o uei hscnb xlie by explained be can this if sure not I’m phases. same the near occur to seem mechanism. flares instability the an Also however. timescales bility eA an Exup´ Saint A. cuando flor de “Mi feliz satisfecho: sea decir Puede est´ que estrellas. para las bastante a mira es estrellas, de rct n asls ae fEaCrmgtmk h hcsrdaiena eisrn ehp h ntbestructure unstable the Perhaps periastron. periastron. near near observed radiative flares shocks the the explain make to Corcoran might help is M. Car could Eta This shocks of radiative co-rotation. rates of to loss not out. due might mass worked companion shock and be the wind tricity to colliding with need flares moving the details the Owocki that are the mean S. they suggested, and could since I though That periastron as con- speculative near to too. very Or, was interesting structures co-rotate behavior It’s might wind periastron. flare structures don’t. these near the you wind encounter secondary in the if but the structures then But 0.96, by encountering companion phase primary large. shock the near the the rather see at by is you co-rotation produced separation that enforced are stellar flares of the strong effects time same 0.99 the which the phase sider by expect to would (roughly) system you the after 1.0 symmetric see spectrum phase shape. we X-ray until line while one system the Also have the about role. only detail a we in play But much with might say system lines. to such X-ray absorbed Corcoran only the M. too is in are there reflected lines binaries Damineli be un-blended WR A. should strongest this of the principle eccentricities and In of periastron, 38) periastron. 47, at loss Rep., Astron. (2003, e> Karetnikov & pashchuk Corcoran M. ab hnefo daaiet aitv ihcntn ˙ constant with radiative to adiabative from change a maybe nfr,boddsrbto of distribution broad uniform, Moffat A. n nl huddces.D o e vdneo ht fnt hnoecuddutta ˙ that doubt could one then not, If that? of evidence see you Do decrease. should angle ing ∼ ur asls fsbtnilaonso tla aeiladpouemsienble–lk around re- like would – this nebulae believe massive I them. produce unbind and maybe system material and the Eta stellar eccentricities, then of higher of amounts to periastron), case substantial systems near the short. of drive happens for very loss to loss way be mass fact, mass may good quire In if a phase quickly. (and eccentricity is fairly high periastron one eccentricity near the last high high mass that the of the of perhaps, like Corcoran state with amount suggests, eruptions a do M. large That more to a to disrupted. couple has if be a move and ask might suffers to I periastron it system at reason if the preferentially The expect occur variability? Car, would eruptions X-ray you LBV similar lost, if show – is that mentioned LBVs you other eccentricities any orbital there are reasons, other Smith N. aia rvdsarr,i iupoeo h LBV the of probe situ in rare, a provides B Carinae sqeu jmlretelsmloe millones y millones los entre ejemplar un que as 1/ aall´ 0 D . n hts(R10.Tesokcn pnn nl hudnro fe eisrni hr’ nacdmass enhanced there’s if periastron after narrow should angle opening cone shock The 140). (WR that’s and 8 2 ,e luaparte...” alguna en ı, eedneo xesotcleiso-ieflux. emission-line optical excess of dependence sd rmEaCradH 90 hc r h w otlmnu Bs n r rubyecpin for exceptions arguably are and LBVs, luminous most two the are which 5980, HD and Car Eta from Aside - D58 sarltvl hr eidsse n tsestesok ih erdaie n h iheccen- high the And radiative. be might shocks the seems it and system period short relatively a is 5980 HD - olntb o ocre bu h ihecnrct.Atral rgntrOObnre aearather a have binaries O+O progenitor all, After eccentricity. high the about concerned too be wouldn’t I - h o’ o e -a ae tayitniylevel intensity any at flares X-ray see you don’t Why - htsago usin meitl fe h eoeigteesa nevlo nacdasrto which absorption enhanced of interval an there’s recovering the after Immediately question. good a That’s - htspsil.Ia o uei h ieclso h aiblt esecreaewl ihrdaieinsta- radiative with well correlate see we variability the of timescales the if sure not am I possible. That’s - o a ergtaotteecnrct,,u ti neetn om hti h eetrve yChere- by review recent the in that me to interesting is it ,but eccentricity, the about right be may You - xetfrEaCradH 90 ˙ 5980, HD and Car Eta for Except - ery, lPrincipito El e rm0t for 1 to 0 from T A N TE BS127 LBVS OTHER AND CAR ETA l existe olo P te Bsaewa -a ore.Itikyuaergt asloss mass right, are you think I sources. X-ray weak are LBVs other ≥ DISCUSSION 0d loi ˙ if Also d. 10 η a’ id hn if then, wind, Car’s m a before enr . rhelr . ul .20,AJ 624, ApJ, 2005, T. Gull, 45 & 645, F., ApJ, 636 Bruhweiler, 2006, 383, P. E., A&A, S. Verner, 2002, Owocki, F. & M. N., Corcoran, Smith, & M., J. Pittard, ongbre,G 04 eMxA 0 107 L37 40, Naz´ 633, RevMexAA, ApJ, 2004, 2005, G. al. Koenigsberger, 522 et 663, C., ApJ, R. 837 2007, Iping, 553, al. ApJ, et 2001, K., 1034 al. Hamaguchi, 547, et ApJ, J., 2001, D. al. Hillier, et F., M. Corcoran, ocrn .F 05 J 2,2018 129, AJ, 2005, F. M. Corcoran, of Tests Observational 105, Symp. IAU 1984, P. Conti, lr,J . ainv .M,&Akao,A 05 A&A, 2005, A. Arkharov, & M., V. Larionov, S., J. Clark, hsmyte esmlrt R10weew e a see we where 140 WR to similar be then may This ? m 973 ezn Drrct edl,233 Reidel), (Dordrecht: Renzini 239 435, h tla vlto hoy d .Mee,&A. & Maeder, A. ed. Theory, Evolution Stellar the .Y,e l 07 p,68 L25 658, ApJ, 2007, al. et Y., e. a after nrae tprato,te h hc-oeopen- shock-cone the then periastron, at increases h -a iiu,atrmnmmw o’ see don’t we minimum after minimum, X-ray the periastron? η a orttswt h ria oinof motion orbital the with co-rotates Car REFERENCES m a culyde increase; does actually η Car. © 2008: Instituto de Astronomía, UNAM - Massive Stars: Fundamental Parameters and Circumstellar Interactions Ed. Paula Benaglia, Guillermo Bosch, & Cristina Cappa nosrainlsaeet o hoeia n) lo(n t a sago xml fti) h msinmybe may emission the this), brightening? Corcoran of (that’s visual lower example M. much secular wavelengths. good the be longer a by must at is suggested velocities emission Car relative X-ray Eta the the (and Walborn which eliminating Also N. in or one). to stars reducing theoretical compared single absorbed a pairs, the more not line to statement, He-like compared observational and shocked, an H- being the material of the wavelengths of shorter and Corcoran energies M. higher the spectra. in O-stars reflected the is shock Car Eta Walborn eccentricities. N. higher with systems into ratios. mass and Corcoran masses M. similar with systems eccentric Walborn N. 2 CORCORAN 128 ht er20. h bopinwssmlrt hti a n19.Ti en htterdcino xicinarising extinction of reduction the that means role. This strong 1998. a in play was not it does what material to circumstellar similar the was absorption in the 2003.5 near that, ol h ihrXrypa nte20 eaiet h rvoseetb eae odmnsigobscuration diminishing to related be event previous the to relative 2003 the in peak X-ray higher the Could - h ealdifrainotie rmteCadasetai eakbe h adrsetu fthe of spectrum harder The remarkable. is spectra Chandra the from obtained information detailed The - eadn h cetiiy tsitrsigta ohW 2adW 5ascae ihEaCrare Car Eta with associated 25 WR and 22 WR both that interesting it’s eccentricity, the Regarding - htsago on.I ae o odri asls ed odiesseswt ml eccentricities small with systems drive to tends loss mass if wonder you makes It point. good a That’s - e.Teecliigwn ytm aehge -a eprtrsdet h agrrltv velocities relative larger the to due temperatures X-ray higher have systems wind colliding These Yes. - o ic bopini o eysgicn at significant very not is absorption since No, - niptbeeiec htSa nosdnigmr hnnmrclmodelling. numerical than more dancing enjoys Stan that evidence Indisputable E> e.As h XEhrns ai uv shows curve ratio hardness RXTE the Also keV. 3