© Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México R sp and the the sumed Small (WR) troscopic eruption panion. et evista ectrum al. HD Bet gian largest sup ON Magellanic 1995; w star at t Mexic 5980 erp een (Bateson, H studies displa that THE osed SMC I of I Ko 1993 que la Key ev Menor 1979-2002 ing ev ev star p line fraction These wind phase-dep Ra derw (star the ana is region the osible 1. time ying oluci´ olution olution enigsb y compa the photospheric describ cluster, Cloud et the p INTR incluy profiles A+star de Wor en NA and nitrogen erio sp A) Se HD Gilmore, allo nature on to t v de N66. most Astr ubicaci´ eed ery pro of erger a ds: forms d presen nera TURE ˜ 1994, just arise del enden ODUCTION w Magallanes with an 5980 (SMC). Univ e the y luminous 1979-2002, cesses onom of NGC strong from an B HD ST UAL ST NOUS Some son los luminous sistema has star prior et cercana on binary sequence observ ersidad in rapid estimate ta part ARS: ARS: t is R & HD 5980 efectos absorption ´ ıa e v al. consisten the en recen 346, a a c that It ariations un of A He Jones OF eive y to (HD m close of el is 1995), BLUE 5980 ed blue the is ww probablemen rotation, pair y Astr as ultiple I an´ the and asso d I and tly diagrama de W BINARIES Nacional a o 1700–2200 de system emission de THE (WN) emission of alisis ccur c 2004 a earliest close 1994; OLF-RA binary of is la v tes region. b los sup suffered W ciated the 5980) rotaci´ ariable-lik supp lies ´ een ısic Cen of similar lik lines olf-Ra V estrella star in efectos erno con F del ultra ARIABLES) ely wind-wind eclipsing and a with ebruary within in tro questioned. Barb´ LBV ort , G. Aut´ massiv on H-R. sp line com- lines with 40 pre- system te Giv the v sistema km ABSTRA la the y HD — ec- RESUMEN violet a YET de an Ko pro to the et y/o , onoma se a a A profiles de e ev clasificaci´ (ECLIPSING) 107–135 en result / s Los Ciencias enigsb vides e − eruption pueda en ST que WR 6; WNE la el binary 1 the 5980 m P t. in collision — and colisi´ datos ac ARS: in m ultiple de Cygni The ativ LBV’s kno is ev c LBV’s An the nitudes, asso H ro That CT of en tercam the c assumed ultiple erger a ma haracterized. epte describir w ST er, I ECLIPSING (2004) classification ev to M that on magnificen F on 1993-1994 whose wn y ely and additional ciated luminous analizados in Small ´ emission o data ´ olution exico, ısicas ARS: HD d originate is, original systems (ww en WINDS, absorption enshrouded is bio except, 2004 1993-1994. of hot LBV HD He and its tre 5980 that mass-loss analyzed star companion’s c) with de utilizando Magellanic Morelos, — I visual (WN6/7) los with , V 5980 Mar its sho t has lines masa. c ARIABLES blue the tuv differs B WNE at p in haracteristics p One opp comprenden vien ST of sp enhanced eculiarit erhaps, c ch is mass k the o had the lines situado erupting luminosit ectrum OUTFLO ARS: star ortunit b 2600–3100 in cone of v tos, rates, The una 10 ma BINAR M y ariable significan de ww trazas shortly this stages lo ´ exico dust Cloud a transfer jor imply B. (star y w y geometry η erup c la erupting WN6 se only y dev INDIVID- region. mass-loss pap en is Carinae, The ionization difference star y estrella to for ev el discute (LBV) ci´ that (LUMI- of B) that elop WS increased that b that la tly er km olutiv Y p on. a allo efore and/or or orbital study- er in stellar W Nub small co from ed ´ SYSTEM ıo s The star it and in w WN7 HD un- olf- the v − — La do B, eruptiv whic su as er episo strong 1 is it e its with the stages . all 5980 erupted. in b h, y stars progenitor. des. LBV’s the an ∼ the e ho and w suc 3 ev kno w eclips- as to Ho other mag- ev en h nar- 107 rel- are wn No er, ts. w- b as e © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México 108 star. ondary LBV+WR ing & after Meynet lutionary (1984) the are (1989), 120 In are loss 200 in limit ities surface p are extremely at v ∞ eratures the this this Da The ∼ exp observ effectiv ev km binary o M and ccurs, lea With at vidson olv 2000–3000

WR ev osed stage s and comp and ) and ving 1987; LBV whic − ed olution, episo O-star a 1 due ed scenarios in n.p. e ) 1995b 1999 HST (1) 2002 1994 1995a 1989 2000 1986 1978 IUE Ep 1994 1981 1991 1979 the system phase system p massiv tense and and temp reviews exp Nota h (7000–9000 onen eeling the (1994), the o to class Meynet des a c indicates p /STIS h osing relativ the ossible a ev phase km Main it erature winds t stellar of of e rapid & is olv of off and, is w (Langer stars core its s large ma kno as Leitherer b Da − es the the the & ely eliev Sequence, 1 of ev exception “not y are Num. increase originally ) winds vidson, to wn. K). furthermore, He-burning rises Maeder · · · (2) sub olution. binary and lo rapid remaining He-ric 6 7 5 1 4 1 6 4 6 3 · · · b w mass ed · · · w e expanding ard presen Once et ject SUMMAR effectiv rapidly found to strong ( M (1997). al. 11.0 10.6 and h lo loss. ˙ in reac Moffat, ma to 2000) a of w t”; WR the core. ∼ defined mag 11.3 10.1 11.4 11.7 11.3 11.3 11.6 11.4 11.7 n.a. 1994; its n.a. m massiv er (3) y violen − − η la enhanced h phase 10 e in abundance V Standard and 11.3 10.1 also He-ric stellar effectiv Car, y that temp an b stars slo − b ers predict Y Humphreys The n.a. 5 In & Maeder instabilit wly t the e M OF b b of initiates, no instabil- eratures the e general, y ( h Lamers

1.8 2.1 1.7 1.7 K p indicates ∼ radius. e LBV’s H-ric a F star ossess la Con (100– 3.30 1.97 1.73 OENIGSBER 1.82 2.07 1.94 2.10 1.84 2.04 other HIGH yr mass (4) tem- 1850 − − − − 50 that ev WN y sec- − en- ers 2.8 3.2 2.2 2.2 T o- & 1 is ti h y 10 – ABLE , − RESOLUTION “not 12 F 11-26 39.2 32.0 n.p. 12.2 15.3 15.6 17.9 25.0 n.p. n.p. 5.3: (5) N 2.: erg the SN of ample, quires has tionary close w SMC, hancemen ma mass profile adv p is the a the of of v the sible to a 1 IV elo v ossible a ell GER review ailable”; the the truly a cm review y Answ anced ejecta p cit stars sp SN mass established. sup b F oten 28-55 to 105.9 105.7 117.1 57.6: binary − 78.8 80.0 82.7 98.7 53.0 39.9 33.8 mass-loss e ectral 24: (6) He wind WR’s y the kno v 2 are estimate affected tra ariabilit ev erno curv in a ering s I tial in of ts − I transfer and stage en in to wledge visual LBV+WR jectories the 1 UV c c the of v φ massiv t es. lac lines. haracteristics its the pair, F of a < 20.1 20.3 20.7 23.2 22.9 28.2 31.1 30.9 23.6 is 20: (7) 13: in 1:: analyze some N He stars k (SN) D pro y 5. earliest history But orbital b system. of V conditions the a The A H y luminosit and of and and since T viding e ev The massiv the completely of A of rapid without the m no 12 no no 1 (8) 1 Commen impact stars explosion. olution, mass ma its lo system, lo V other our phase. these rotation in lo φ φ φ stages? ob affect w w fundamen they Because teraction from y c c w one comp ∼ e rotators? jectiv of res. res. in ∼ ∼ y curren sev that determination, res. binary 0 of hea questions, a of 0 0 the . ts general). of and 0 pro erly . . S. the b in 36 36 onen swp52824 swp1598 (see then the es vier etter mo Th the only prev teraction stars, Duffau t duce HD tal effects nearing distort expansion of understanding us, dified system. Massey ts? clearest system T elemen ail it understanding this o parameters 5980 HD emission-line it is ho what Ho just If is within the w the pap in effects w HD 5980 the ho ts. is ev not 2003 is insigh prior F will a degree w of er, or ev in er radial fairly Most ev 5980 time v p olu- has the the the ery are ex- os- for re- er, its on to of of ts © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México serv ternational Moffat, b the complete data b rizes flux stars data ep question they within serv wind HD out ep A. others Fig. erger erger, o o 2. Jones c The c of Hubble ations ed h 5980’s at h 1. the are O b of v comp are eclipse. of (triangles). elo et VER (i.e., the 1850 et Kurucz, Ko 1978 data w (dots), general observ the of Visual cities indicated. een set al. are enigsb osing Sp c principal the VIEW Ultr haracteristics, not A, ˚ only ac and analyzed (1994; λλ describ of within ation, nature Fine e aviolet and ligh corrected & c 1150–2000 the erger, T high haracteristics Sp a 1986 elesc OF Georgiev v t The Error ectral ailable a system. emission v ed 1998a; curv n the and erage um THE resolution Explor op & are in arro in e e Sensor Auer system, b t for this ev yp de with er (HST) sp included of w A ˚ observ ER 2002). olutionary 1998b; es ectra er Bo of reddening) indicates lines. obtained HD pap of (1989), corresp UPTIVE on sp an Satel er these . and UV ectra, ed er Details IUE 5980 & for emphasis T in 2000; Lo able lite Sa constitute flux to onding sp these and exp data, w (crosses), this status with v LBV obtained a address ectroscopic age con (IUE) CYCLE v disp 1 ected con of erage Ko Ko summa- table ep tin / suc (1980), the the to on tained WR ersion enigs- enigs- of o uum lev eac h c and and ob- the the the ob- the In- hs. b as as el h y SYSTEM 1993 had classified (Niemela v Because the ev Fig. strengths, satellite UV except (1993), v b T m data phases outburst of mon data 1 is ations ery e able unit ultaneously at olving T HD summarized The sp able dominan 2. th a φ sets incomplete (just b ectrum w 1 WN7 = Mon near et 5980 for earlier. as pro p also based sp w 0 1. observing of w ossibilit WN3-4; prior et . made een a 51. tage as ectral b vide the 0.83, their decrease classification. efore t al. lists of first A with degree 1979 on v illustrating HD to in for 1998). the alue constan Due except y c in the larger the haracteristics in 1986, terms suggested the that displa 5980 the time, most general, and in the of visual of to abrupt c line t In 1994 hanges corresp HD for 2002 as ionization n y of late incremen the 1991. detailed um the orbital purp The the a noted sp widths, magnitudes 5980 b (dotted b gradual ectra but 1980’s long strong brigh whic y er, 1970’s, oses. onding few detected Ko prior These t w in the phase term particularly h description obtained enigsb tness in as in and sp the sp it w constrain increase to v ectra undergoing the as optical HD ertical ectrum) UV w c a c the hanges obtained last as hanges co increase) erger in obtained decrease sp 5980 v data at a WN6; eruption erage the ectrum. v column shift ailable in orbital obser- of ts whic in so et w line set, can UV 109 the the for al. an si- b as in in in is it h 1 y © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México WN6. WR’s suc HD t This (Barb´ ance first and tributable at 1997). sual 110 of con Garman ric (1975), to in b visual feature as fined in fau prominen from 1989/91, data scale note the a He pro the coun (1997). m trates b Th eclipse, for v time exp due assuming w alues een oard correction v een us, 1994 2002 t h these 1999 I eruption vided tains The data ected these ∼ sp ypically visual I (2002, a 5980 observ ts to brigh visual line, of according it sets. 1640 detected. (Ko CCD as a no ectrum 11.7 t 1981 the (see Figure Hence, for The magnitudes, measured ypical et is and the started this y v data w from (2002 denote obtained A an brigh t a b enigsb data is 1994, ep t arising tness: al. (1989), also A ˚ IUE magnitude w y ypical 1986, N ed G mag priv to Cro In magnitudes sp photometry m and comparable o ell-dev eclipses. the of line observ Alb indicate den P 1995) IV c are ultitude p UV in ectral Barb´ Car hs F tness the 1 1979/1981, presen Marc oin ate +0.6 wther Cygni are and to e erger Figure 1995a, to b 1718 arro 1986 1986. ert The v sho marks V from 1989, the b is eclipse et Bergh alues sp t and significan y curren b elop brigh or ed comm a w in as m of con and et Jones lev h ectra ws w t mag the although een yp strong A. ˚ et t. sp lo WN11 et v emission & w estimates a in 11) a The ab 1973 Ko its of ed el follo w-disp 1 v 1995b, een and es ectrum ∼ that from the that In al. ten. A sp semi-forbidden with Fine erted kindly al. depths Dessart (1976), F t unication); 1973 o LBV of summarizes as enigsb N for w e v are (1987 ectrum 11.3 higher-temp w denotes activ the 1989/1991, ws: e t eak (1995); the out-of-eclipse VI 1973-2002. 1998a); IV transition N eak discussed w 1991 (Heydari-Mela w c this sev HD Error the The Azzopardi as ersion hanges correlated , V ] to and ere er temp 1999/2000, outbursts dominan lines, system 1486 mag. e is pro w of erger obtained O en 1240, (1) through obtained Massey a 1998), phase p eak LMC co reflects emission 5980 obtained V ∆m range similar oin 1981, vided visual a ep and Sensor eratures (3) oler data. A ˚ 1371 and T (2) in v o the et t Figure b Si C riangles v alue from out erature c the emission y indicates t R136 transition, hs: the remained initiated Dots The , ∼ IV the the IV with al. for Crosses after in & Breysac w ha b 2003) features and magnitude A ˚ photomet- P brigh v during Assuming y 0.26 of to eak 2002, sp (FES) y ariabilit 1550 ark a 1979/81, obtained from lines v FES (1998b); Vigneau 1400 WN5 P ari brigh triangle v app S. e sources eclipse, K ectrum 2 as cluster denote ailable the LBV’s kindly er Cygni whic er, OENIGSBER nev tness et prior state illus- mag. Duf- with line. ear- and but lo her the the b de- de- m ter at- vi- al. an on A, ˚ to at er of e- & w is h y v lines prominen no HD w includes Si blend. or sp ing illustrating lines the undergoing stronger 1993 1995a), A minous (FWHM of companion branc 1979 blends ure early tual iden clature, rier tion nally HD merous and date, b pro 2000. (swp4277) sion No y ell GER ectrum, I v 1 is late 3. during I sign vide em Sterk W Unfortunately Hoffmann, The A SWP descending I 3a. P tify 5980 He (1980; line 190603 as orbital , in a of sp classified h and e similar and b O-t THE N Cygni comparison to er All of highly the no I ectrum 1995 lines of of N stars the Most I eac HST I first en the strengths 52888 an I yp 23. 200 , than t to I w suggest still V mid-1994). swp52888, and the the , lines, the in and F greatly h STELLAR the e , henceforth & a ( Al p sp LBV-lik b e (Ko b − that P highest N (ep of in erio previous to profiles, star. e constitute V sp eliev transition, of or v 800 ectrum Breysac N w eruption I to greater prior broader maxim branc tro an 1989 I ariable is narro Stift, I the as ectra b v, and enigsb I o except those the V =19.2654 d , b dev c HD compared as that duced e ma km eclipsing h e kindly He enhanced 1240 w W no b three e that a w 1 h (swp37788) strong w as to F 1995b) elop et qualit y e um 5980 (ep I eruption; WN3/4 ell e s & her displa from The ep obtained erger of the I COMPONENTS emission-line star presen w emission − ha BP80), lines. UV adopt N , found VI the ligh A ˚ the 1 een o b obtained as the ed and C o at Moffat v ) stars. V c . of y (1997). c trend emission e hs. y emission SYSTEM IV hs first da t whose binary lines photospheric ions b ys 1240 In with con data eruption. Barb´ least HD et sho eruption the UV y t UV , curv part the ys), hereafter b star; 1999/2000 By 1989 v and Figure y in and al. tin during w star ery lines high for illustrating suc 5980 A, ˚ at con eruption Breysac a b swp (1978) e , three data early exist ued the y wind sp a whic of The 1996). and although et the line displa increasing λ h are recen lines, strong is S. tin fluxes ectra smo presen this resolution B ligh < 52888 as al. sho system: un 3b, B1.5Ia the Shore h uum The star N this 1995 significan a t 1500 hot that structure just IN is w oth v til her absorption tly C disco t wn and (1996), ys w I most ailable transition o I the (b declining the curv There as emission I I in of t THE the I eclipses nomen- and lev the sp C (1994), on narro the & refined et , (ep 1750 in transi- during w + A ˚ b 2002) v emis- origi- N F same ectra as w efore close 1979 is el. star e, ha y ered P Fig- 1994 star e o UV een n ear are IV ac- tly er- lu- an c I as u- to to so v- A ˚ w is is I h ] , © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México trum gion sequence, (star plying the The (star w significan and are cen 20 obtained star e Fig. The M B, 2002). bit ere = B ◦ tric corresp The not of =28 opaque and the 3. 0 B observ x, surrounding not . A B w 27, star Left: is the y corrected as orbit Figure SMC “in eclipse “in the in axes tly M 15 separated Moffat star clearly onding er A, 1979 presence

Sp fron region R corresp fron broader , star ( is

e ectra are in P B 4 . observ t”) lo (dark) = =19.265 for t”) w illustrates a et The MPG that cated star to in as 0 that reference of reddening, onding at equally . al. at of 32, units the iden than HD op ed phase and B. of 1998; 355(ON3I an φ at pro Breysac en da a b parameters: tified 5980 Since = y extended 1994 the of orbital the WR ys, duced squares in the BP80 0 frame φ e R and . obtained time: 36, b e = =

primary as (dots) =0.27, the geometry ottom her star I , I(f 0 0 no the the and phases indicating . . at 30, ∗ 0 cen are comp & ) and primary of relativ and illustrating W WN φ broad M tered of P in the and Kaufer placed the alb LBV eclipse, errier = A opaque 1979 osite the are secondary of =50 e orn star, radius 0 ω nitrogen . displacemen on / con the =133 36 figure. eclipse an noted. WR (dark) ev 1991; et et sp M star and w tin- im- details ery or- ec- ec- al. re- al.

as of ◦ SYSTEM . , 2000), and of t 1989 has the gular (star analysis uum PI ject 1978 not nosities BP91) 1994 the ligh conclusion Ho an et exp 3 the illustrating stars. al. b w HD D. (dots) c HST ected t” een image system hanges equal ev less eclipse (Prop b B). (1989), distances W er, source y 5980 yielded in elt of Niemela of Breysac than image compared tro The p HD 100% of y), that oin in the osal the the is duced w HD based the as t (star triple precluding fact 3 5980 h V on v t obtained spread the 5394, uge asso w mag her alues suggested -band sp (1988) 5980 b o the with that ectrum. et on C), flux system (see app stars: ciated and w fain dataset een order for optical w function the ligh eared the lev and had as b the ter with P the elo els the SMC errier the with t more is 41% sum of th w) already curv than presence in sp most observ U29T0101T, as the relativ us 0.1 presence ectra. binary HD its and for (star of extended (1991; e a 00 they HD WFPC2 , of stellar lik p luminosities 5980. a ations consisten so oin suggested e ely Righ the of p system A) 5980, visual reac had oin t henceforth, of a formed source The system wind. t: and third t than in a F255W, hed in Massey Sp source. at “third Sk t whic fluxes lumi- ectra with Ma that 29% 111 108 did the the an- ob- An b on in h y y © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México b corresp absorption photospheric nosities sub-arcsecond sigh ev jected the t v V follo b of that 19.1 et Moffat, large HD amplitude a WR trated mo Since 112 and 30 brigh originally thermore, sp cal at and the 1989; the tems, of tem; are comparable and are ing rep yp elo y ν erger C er, ectra =0.1 the al. the = the date orted km sp e suc Adopting The Photospheric t sum cit similar p smaller w also finding MPG 5980 N the − star. they or for ter. ossibilit (Massey densities, ob ectra ed 1998), data these W shortest the 6.3. y h V in rotational et three follo ond s (2) of & giv ject. UV con mag, − alb this ON3I (R luminous of 3.1 star 4603 lo b Fig. al. 1 do in The though Niemela y 355 the Niemela con cated en V) of of the wing: three orn to lines obtained tributions reddening . o of to Moffat lines at (2002) luminosit m 1979 y stars v indeed star, absorptions Star HD In m tin 3a A’s ab A ˚ er no I those binary observ a uc adaptiv curv fact w et that those Heydari-Mala I((f*)) sp she shorter v et a an o emission uum h =11.7 where distance absorption the of t ectrum con in v v 5980 v more arise al. orbit WN3, (1) and C: in elengths, al. elo e, stars to to (1988) e that 1982; found concluded et analysis the the ha of the tin o ed of for the 19-da in 1978 system cit the y 1989) b 2000). lev e al. star from star corrections v obtained an small 1989 elong the only ua, mag, w e HD than of fluxes optics the implied y ∼ HST as 1978-1983 el these and SMC. of absolute a henceforth b R (1998) Thir that O4-5 lines sho v v mo HD elonged 50 y V MPG are flux-calibrated C WN4+O3V+O6.5I, star elengths. in star three R 5980 at lines sin of and in are y for orbit. Sk v w she V to a ∼ dulus Sk km d eri UV is that reac ariations HD the observ whic 5980 ed lines the V mo t reddening stellar The curv Comp C prior yp star 108 the A 50 A i a could itself compared 108 concluded eviden at 355 et the that s hot = visual ∼ v consists photospheric hes for sp v to − e 5980 star UV and h ed − yielded ery km e to 1 λ masses can They (WN4+O6.5I:), star al. with BMN82). ectra, sum 75 ations. A HD a to 6.5, and onent of (Massey stars, R the lev relativ > Th in a b the winds third, photospheric the V A (Breysac t smaller star e hot 1400 (1997) ∼ km s the differs easily magnitudes binary els − with 5980 in an us, due w of a amplitude V correction MPG three N sp 1983 1 suggested of Ko B with ti-phase. as the required SMC that a N s that p sp as e IV B. (Moffat ectra K = strictly Sk − line-of- assum- A ˚ ha ossible to a is V enigs- radial also ectral 1 OENIGSBER − et Ho lumi- acco- illus- opti- from from 4058 than w lines ving only F pro- her, sys- sys- still and line 6.0, one 108 355 but the the are ere ur- w- al. of of a their based sion whose Fig. t (Breysac lines, tin sibilit pap C tationally line-of-sigh Ko resp nary photospheric conclusion. no ducing binary collapsed a con Ko & con w second lines spheric are trum b a tions, and P undergo p 1997). that the stationary absorptions absorption the yp 3.2.1 e erio eter ould pro collapsed GER is St.-Louis uum enigsb enigsb attributable e tin tin The In evidence er close sup “third onsible , on gra 3). lines d jected do up (probably y . systematically b or uum uum and one Con summary on: not w only ecause of p Evidenc the system. the of erp absorptions energy vitationally on evidence e ossibilit small-amplitude her not whether This erger erger orbit companion star shall still ti from con b prior (1) t UV osed absorption ligh presence whic lines sp ob eruptiv flux equatorial 3.2 ound con for w It (2003) 1997). to also displa for absorption ould ectral tribute ject conclusion of A+star the . additional is t” (see distribution, e (2004a) et emission tribution , a assume p HD h to y similar Star on lev to F consist Pointing the c erturbing p y , the distan suggested third of it hanges they or al. et w concluding oin not app e y either els ha discussion the v Hence, asso ere b 5980, of is energy ev the ery existence large example, to increasing A strong in significan (1994) ound ting v v lines earance b B), en are photospheric simply e are elo sho t asso star and that e b time to orbit ciated of lines suggested eclipse lines. t; broad to star R e directly star unresolv do in to cit to or V but w enough also MPG determined to sup a for stars (at ho ciated the distribution, photospheric es its the ed (and in y sp the star v Star star blend of that , and around that w ariations the t summarized A a tly erp of the of with ypical v Villar-Sbaffi, these eculate not least the Eruption ev the consisten and sp in ligh p line-of-sigh the sin or orbital A A star a er, 355, visible ossibilit C v ed A osed. tensit A+B to one ectrum with star remainder star R ariable) the exclude system n feasibilit of as star and t star absorption V is o as i v um the eruptiv lines stars there star v ariable curv of ∼ C from t the er illustrated an that presence A v w whether b the y HD C b eclipsing ariations 230 Georgiev B. B , in ecause UV/optical A. its is t o parameters er y absorption the nor could e is B. app O4-6 eruptor and is along with b con based has the and Eruptor could t emission that a the The Star e y of y solution sp a km its 5980, Moffat, itself ob If orbital photo- star of to Smith ear ev of tribu- gra ectral emis- sp their b ha lines suc they ject. con- p pro- s star star of en this this UV een A’s the the the the − os- ec- bi- vi- on b v to to in in & 1 is it t, h a a e e . © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México star emission line also et v bital orbital its come tered (BP The (Breysac ter b et cen 1980’s, Drissen A, t lo found This (assumed 1980’s on that Niemela of b increasingly the sence also K with pro ligh dius orbital of He the R ten fit noted w ariations, y er) V w N o to 2 the al. al. I published subsequen t as radius. tly ed then duced I The The As The tcurv v 1983, stellar presence , V and found with stars, ma A from ariations after the c leads the and 1980; motion a (1998b) 2002), at of hanged m opp star that b late (1996, sp ∼ motion (whic H-abundance leading men motion y uc jorit larger H. sp et H-con orbital her the also e; needs et pre-eruption ectra lines. pre-1980’s the Niemela, osed b p the h 128 ectrum. eruption, to to B. wind b 1970’s y M 2 al. ost-eruption the a and tioned al. equiv y broader y 1991) indicating F h Large more a 1997), t the of notion A of con The b of e fact Barb´ N whic estimated since 1999) to ten wind (2001). and H-abundance is to of e (1997) N app ep V to of phase star In ∼ some IV alen (3) these lines b tributes conclusion /VI that “in star V t o e the follo semi-amplitudes a star h massiv 50 c that displa p the a, estimate ear corrob Barb´ deduced ab 4058 K t 4303,21 hs ha implied the that ric ost-eruption the are A leading in He this fron width N Niemela, N near A lines o H w φ M lines to ving of her (Ko v UV, to A; are the This the ligh =0.0. ed I I IV (1994) consisten e (Niemela can a, late

N[He]/N[H] H-abundance I as orated V ys the line t” estimate line e star to b emission (2) for emission-line the ( & the enigsb and v t follo predominance p a stellar are e dominated early § ∼ 4058 that alues A ˚ the at a b ost-eruption enhanced from the leads b to negligible (star 1970’s. consisten y pre-1980, Morrell no curv This is 3.1), e the emission sharp B) 226 orbital with time & sp φ not w, c M the N hanges =0.0) explained found star emission. longer of H-abundances t R ectra erger as Morrell et B e while the in IV increase wind the with V to minim A). a presen of km H-Balmer line of Niemela 1986 al. conclusion mo ∼ ] of ∼ general, A data minim the (1998), the ho Ko motion 1486 t activit sp masses the while inferred has H-abundance et to del-atmosphere Evidence b dev 0.4 28 1998; s line the w in presen with sp in LBV sp the − y the ectrum enigsb ev um (1997) t R ligh Jan al. of conclusion 1 follo whic the ectrum. ectrum eruption. elop M , V the increased er, pre-1986. (b if the in exp More um emission R star lines the y allo 1998a). sp

has y t / uary curv V system Kaufer the star consis- an is of (1988) its of WR ts w visual phase . curv h ed ected n erger ectra early wind based from w data that cen- pre- um- w star and has A’s fol- the ab- the R Af- and b ere or- ra- for re- es, an ed e- A V is is SYSTEM e the eruptiv Sterk A, 30 spheric ated timescale da that He data 77) w but the that there are somewhat of listed. at observ Fig. erence 3.2.2 eak ys). 20 HD HD y indicating I According Breysac The rep lo kno I whose ears. 1970’s. 4. ◦ . star . of en with o w er are or in frame ccurred Char This 5980 e ort er 5980 Represen wn sp The 1973) terv (1997), is large phenomenon nearly A for hea no ectrum at sp strong a puzzling her to als acteristics is initiated suggests second that If the ectroscopic precursor WNL’s vy-elemen the c rep b an H-abundance to and hanges b & suc e tation the absen et b orts gro is whic v the SMC ottom. He W w the h ery fixed eruptiv een and b wth esterlund instabilities I in p prior strong ecause I visual t h corresp of in Ne ossible this H-p t photospheric (∆ analogue the He ma 1993.8 c the The abundances. its with of more ar haracteristics m o to e y I the w or. , SMC, the effectiv v orbit He phase ligh in onding b ould the op 1986. while resp c e ∼ (1978; hanges pronounced instabilit en Eruption I star On asso and t of but 1.4 WNE’s are ect of curv squares indicate and of e orbital Galactic the W ciated star absorption A temp 1994.1 to mag) only HD related data alb in e it differ is, star other y of the orn Maximum A is are in 5980 erature is phases a with ho that eruption eruption Jones of p in trace at ( general WNL’s B lo ossible photo- ∼ due w to (1977; hand, 1975- . a cated initi- ev least star and The 150 113 the the ref- are er, to in of & © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México lo formed observ absorptions v m and increasing that s explanation that star lo C sil” lo Si absorptions. the the b at A (swp1822). there and of in mo Mala determined ature of ilarit P the the con ∼ ure more clining starting ligh are started this initiated ness at 114 − elo e tlas, w cit um. cities IV Cygni 1 IV 30 the Si a an m del er . tin the It Ko t other fist illustrated visual cit wind LBV 5. y C during second the y ∼ the y B1.5Ia These v IV within the y da , curv structure. P is ionization eri ues ∼ are ed enigsb y IV This corresp and with of ∼ p 40 B1 trend UV signature ys, fit (300–860 in in notew Cygni 1393, in structure. ost-eruption slo features. , 21,000 in sp in P et hand, ejected e A 11 the Si whose da imp ligh a ∼ out after sup th ectrum 1994.8 w G + to 1994.5, that the features wind the Cygni ligh al. b for the ev I the ha erger ys radially In mag I us y 1994.7 v of gradual That onding star I orth t Carinae w ortan en ergian 1402 v elo in a lines. B1.5Ia (1997) phases later the this tcurv Drissen curv 1300, ard, e particular, It K range the whic the is exception t (Si maxim w during km the cities of line sp y et This first b (top w ould (HD absorptions whic sho reac of extended y t is, scenario I That e. as that are ectrum width (Figure visual al. t I the h e (∆ and whic expanding UV constan s amplified differences 1995.4. + decline Another C the wn − − – in profiles in it just declines do information the hing ∼ h suggests corresp of b um m (1996) 1 star, illustrated et 190603), 900 I the Al ) e brigh “fossil” the I Septem sp es the h is the v is, 330 in Fig. B1.5Ia expanding than implies 1335, al. of absorptions I prior ligh ∼ v ectrum, the excludes I similar maxim not eruption and do 6) elo I the obtained implying t Si lo the with ) W ligh 2.5 the tens Th da (2001) terminal v find ond w 5). t es sharply arising imp ha IV cities p are ery alb do strength an wind, displa b − curv ys. to lo ortion + b ionization us wind line and pro t based mag). v er star and et 1750 the w the It sligh e um orn in that to ortan the effectiv curv is the star far is to similar er w the 1994. vide slo e, These are follo and at the Figure a similar app from een a Al a y same sup visual C the with b from panel v  that b lines et tly w greater rise shell of but e v of km SWP similar constan y on ailable suc The y t HD duration IV elo er I ∼ Ori. a and ws ears expanding lev I p , 0.6 erp al. swp52888 e the feature Si I Ho 23,000 p ossibilit and Heydari- h 1700 to the a s to edge P cit P displa features temp slop v oten 1854,62 left eled of − lines of K the IV 7. decline 190603 brigh to of osition mag elo 52888, (1980) w strong NL Cygni Cygni 1 y width maxi- Jones OENIGSBER to those Ev wind ev . Si “fos- than then t only that sim- ma Fig- e and cit tial TE the km On de- v v er- er, off b IV en ys as in of of e- e- K t- is y y y e slo of eruption. Indeed, lo the 1402 1850 w emission the and p cen illustrated in tions Fig. suggesting densities absorptions” sion out and to onen eak cit GER w b m Fig. t e result b er second 5. y ultiple A − line of er A ˚ y A. ˚ are particularly ts, ma G 1500 Amplified v Stahl (top) the 1 emission-lik evidence elo Eac Car (FWHM one line y at separated (b of in b cities. that absorption-line shells, one km ottom) the e h during sudden et of and (Stahl (or Figure found mem whic al. s corresp to p the − for ortion discrete pronounced t 1 ∼ eac Suc w (2001), 1750 e and b the b (Ko h o in wind et abrupt er 200 y c 8. features h hanges h P extends what the onding descending al. of expanding of UV enigsb These a Cygni-lik km km the emissions) c the stratified 1983; splitting these profiles hanged c con app s s hanges in visual − − in lie erger to doublet expanding features tin 1 1 the . ). ears LBVs regions 2001). ∼ at e uum branc with of The Three abruptly absorption ligh that 800 et wind wind in − to Si indicate 1200, suc t has flux al. h the IV are t successiv km b curv of w As is of e additional v h structure. o w 1995), 1393 observ elo “missing wind an a reminis- lev the as s ould p absorp- e − − from strong oin cities, sho 1 els emis- lo 1340, R127 com- 1994 and and w ted v ely wn b ed as er at e- a e © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México ∼ timescale where from written features resp w Fig. the eruption th swp52888 minal shell expanding (1994; (swp1822). faster uum N eigh us 1700 2 col The line-of-sigh . ectiv 7 lev ha of 6. the t, × = M wind terminal φ el. ˙ ving km 10 lo =0.51; m as: question ely in wind is system w H 23 implied w Comparison er shell. Both the s . sp µ as − swp52888. is N expanded The ( 1 densit eed, col r t ma the ligh mass-loss wind obtained 0 sp to / sp in = is 100 y After eed total t ectra mass b and HD still y 1993.7 whether tracing) 4 y in π b R to the µm et out 5980 question b

r column b in M are of 0 rate, w et That )( in a ˙ e M tegration, H een w is ˙ or v observ visible h to slo v normalized 4 een ∞ 1994.9, and ydrogen, due a ∞ the 1994.2. µ / w 90,000 the signature 1700 r is, Z er densit is 0 ∞ could the sp to inner ation the o t r one, ectrum from dr w v − this km er B1Ia the this o 2 mean or y The v ha , states. to radius ∞ the / leading of of LBV wind 51,000 s v fossil Fig. + of can ) the is e gas sp the swp52888 ∼ sp moleclar cm emerged the the / ectrum ectrum con 1 b is: WR of 5 along − wind Si e y to pre- R 2 ter- tin- the the ear (1) (2) re- , IV

a SYSTEM , sp w b lines ing densit A at Fig. corrected times (2001) Si detected and resp with scenario, N Finally where yr w v HD edg y e as col Si − eed I just Sa HD I least If are 1 e for I IV 5980 7. onding emitted most = . in v the and y w − at just age T Line M ∼ , and 5980 b led recom e ˙ 1700, the ypical obtained assuming efore 4 sp four whic 9 are let for ab assume of × & Si is prior profiles to ectroscopically th wind SMC 10 o in the de us indeed IV the the v − bination, us, h a the distinct e-men 13 1993.7, Si 670, Bo assume the scenario ionization Si to cm SMC mass-loss renders v along abundances that for in eruption er that elo in eruption and wind − due tioned swp (1981) 2 the cities the . and motion. episo and the the that − This the to 52888 in plausible 430 terminal WN7-lik , in assuming lo as rate stages. emission-lik c fossil whic considering is and line-of-sigh and terstellar des haracteristics N(Si w maxim is km app exp er are as similar V in h Ko that of a densities s ertical ears 1700 IV − ected e function log star units that v 1 enigsb um. decreasing sp Ho )/N(Si) elo . µ (Si/H) they to ectrum medium to ∼ w t cit km A e lines a a to of ev to It b 1 the features y fossil erger underw w in e of er, w 10 w b represen is s HD c orst-case the − e ∼ e hanged, ould the v ∼ indicate column − tempt- 1 elo of obtain in allo 4 10 et wind wind wind case. Si − 5980 star cit cor- M 115 the en − 4.5 w- al. b IV in 2 y

e t t , . © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México at ing − M b the w b wind sp trating Assuming Fig. 116 mass-loss the et eruption) c to w that to h eac hange ˙ y y yp as ere 1340, ectrum − 1.6 b h al. Drissen Con ∼ the orbital othesis to 930 same sustained e 8. v v made 10 × ∞ elo computed. distribution, 1998b; the − suggest in temp 10 − erupting (A) Si is 1500 3 cit rate, − wind and IV still y at discrete cycle, M 3 a w on ear. et y ∼ oraneous ould M

1393 p and this homogeneous, b al. presen 1994 1750 1995.4, ersisted luminosit swp53216

sp that et yr and Assuming w p star, in for eed establish − “emissions” This and ossibly time een 1 Decem km t this the , the data that is 38 similar the visual 1402 and, 1993.8 allo s the also y w da − single inferred jumps − and and the 1 as b acquired system wing ys 1810 the p er just hence, that on leads eriastron completely later. spherically lo trigger and to (start temp 30/31 53226). ev timescale cated a km are b a the en v the efore mass-loss elo ma to UV determination the erature s t. in − of asso (Ko at for cit v y the 1 mass-loss alue passage. . Septem the optical the y − ha observ The eac ciated enigsb The 930, o dominated scale, symmetric conclusion v v precursor of eruption. e obtained h er emission K lost rate abrupt star − ations b visual whic depth OENIGSBER erger 1220, er illus- This with rate up A. of of is h lines m φ saturated The ter for data He resen and N crease Fig. squares as sion v widths) Differen v mation the alues alues um < IV GER 3 a eac I v The Using I 0 ] ariations 1981, t crosses lines of p in 9. . function 1486, 1640 50, during h eak orbital on of after ep has around the of t 3.2.3 (0.92 visual and the o absolute sym observ The the of A ˚ c in the and the so h top in v tensities (0.08 the . N crosses and < the phase 1994. ariabilit phase b Post-Eruption of adv con these flux He V ols brigh IUE panel φ ep ed eruptiv 1994 1240, date, tin N < an < I flux o represen I c flux in φ 1.08), tage IV con are uum 1640 y tness h φ detector terv are data = of of ] v eruption, 1995b. tained < 3 at alues N from 1486 the 0.0 e of flux A ˚ N als 0.25; least con IV the triangles ev of pro  t emission V line are giv ] en lev 0.08; differen tained A ˚ (as star data other Char viding 1486, 1240 in squares t, in en els. and strengths, lines Figure lo opp but reac ab the A triangles data w acteristics phases. listed and lines. (0.25 er 0.50 and o unam within osed t reac con v the hing e, orbital N fits limits. < 9 obtained tin indep but V He He hed biguous < to Squares in in to sho The maxim are φ ued 1238,1240, φ tensit the I I excluding equiv I T I the enden a < < phases: ws able 1640 1640 0 dotted maxi- 0.50), 0.90). to emis- . infor- 25 alen data The y rep- um the t in- af- of 2. A ˚ A ˚ < of t © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México illustrated in tion trends phase and rep finds φ N wind a resonance h pared is ter, th sumes This N for it Niemela fected He predicted winds Fig. uge sligh ∼ reac us, pro V IV fron I ort differen Some Plotted I indicating ] data 0.0 data 1240 10. is 4686 that duced scatter. region. the 1486 hes with with tly that b v t), for consisten a y ariabilit et (op absorption R either A ˚ at A ˚ maxim of decreasing excluded): the there broad lines; al. A ˚ Orbital t V no b the b en that on through data y orbital blend 3.3 phases oth the emission, v (1997) large in Ho ariations least-squares squares) that the . differen y teraction geometrical is t um (2) . of stars earliest w from Star and with ev phase-dep nearly (top scatter lines N same phases other of in a it this cross-section er, trend for V semi-forbidden B: emit BMN82 ho b 1995a. is v t t (triangles) there oth ariable w up panel 1240 suc w effects. φ orbital line formed in the o scale no than ev is displa on v with ∼ He factors: stars h enden fits estigations or er, asso WR ep A ˚ is is 0.36 as V (op closer I of I atmospheric as near alues is o an not (dotted emission time. displa y are The He 4686 phase ciated c in t en Fig. not h-dep Star? is obtained N only (triangles; increasing R (1) a I also v squares) significan IV eclipses I insp V of R transition, ery saturated, v in ys 1640 V 9) ery ] N a with N endence; in v of LBV illustrated. lines; 1486 ariations their ection, curv small small terv systematic IV IV displa line HD if extended A ˚ eclipses. ] ] orbital- and / displa es one 1486 1486 als, tly star A ˚ or trend; WR stellar erup- com- scat- from 5980 ys from and and one the the the for af- as- as of A ˚ A ˚ B y a SYSTEM t not tion in evidence radii of nifican trum. of a b the the in R orbital orbital v fat tra. the b a 1960; He the and 77; lev Fig. w ery y y V significan c star o el the the haracteristic the 1. HD I et The BP91 underlying 1979 BMN82). v wind eclipse I really sp stars. 11. This × for similar with ariations of 4686 al. Breysac 10 ectrum B. wind-wind tly WNE An HD 5980 motion timescales b original star − sp Av ona (1998) The supp of that 12 v from smaller. a ectrum additional ariabilit when t This erage whic to star 5980 ergs WR stellar B fide fluxes swp53226 t her orting The curv C of those yp is of the h that to IV A, h raises cm the star e star, sp the WNE emission yp collision & at undergo star e y line suggest is and (F are ectrum leads There − wind , eclipse in othesis of 1994 W 2 λ the is together east, B based 15 ca but s 1979, not > esterlund He the B of is − He still is stars v 1500 R 1 WNE to eat whic sp narro (BMN82), 1994 “in I are, I corrected A ˚

es (ww an of I that I line p Thac ectrum. ligh a that − observ on th 4686 emission ossibilit radius to 1 HD ric c A ˚ are fron early h, us with hanges ho c) (ligh to w t nature the a h sp the k est w when star 1978; implying w curv exp region 5980 do era align significan t” emission-line as ectrum ed ev t) for O-t the that long es at y WNE of y shifted er, prompted ected lines B illustrating e, , in in that reddening, not in of colliding the yp star data conjunctions, & is fact four b b recen w duration FWHM star 1979 e et ecause a their in as ma W con follo classifica- to t star w A, star WR v that of 1994 fraction esselink ertically deriv een lines y t tin b B. (dark) whic w 1975- origin e sp sp Mof- arise with with uum B that star sig- 117 and the the the the are ec- ec- on ed of of is h © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México The to (swp1822 The malized Fig. 118 gion a F emission, implies He serv sp the of w (Barb´ N the con Niemela’s ations men R barely w sion in lar ior e V ould ere ectrum IV IV wind He syn I the tributed, The wind; consisten I conclusion ations v b t syn 12. difference ] in surrounding ariations are eha emission. obtained thetic a corrob and 1486 also of detectable thetic sp star the & eclipse and second Comparison × vior comparable illustrated ectrum while i.e., N 0.41), Niemela (1988) N. only b presence (whic IV e orates B scaled t sp erasing triple-star of in resp with effects it in ectrum that but in star line 4058, in N N could and N h ∼ star b 1978-1981. onsible IV in V the WN4-t 1995). y the do IV the its w in B b 500 of with 1240 of whic the et 1981, e 1986. 4058 O4If es and B w 4058 (dark) the later evidence w origin b system line an presence asso as km e een not (BP80; h R yp those for and Th formed extended V previous con in an is (swp06967 is e but ciate w s the observ unam the us, − v During He ere that (swp6999 formed in N tributing constructed lines In ariations. orbital 1 observ IV normalized w is I BP91). amplitude star the broad of I no the with as in biguously ma in ations that 1718 of figure N semi-opaque longer explanation ed × clearly the in y Si B. the 1981-1983 UV IV × phase 0.30) line-emission b star I to a 0.29), in pro could I e This These I 4058 ww This dense earlier b (ligh w , sp mask with swp53226. oth swp53226 C vided ards R detected ectrum, c A) sp presen K lead V IV b b region t) B1Ia sho OENIGSBER eha emis- argu- ectra. ed e stars , v data stel- nor- this w ari- and and due ob- the for re- b b c as to v- + y k y t ted He w b pro t least from star origin He φ pared is B els en w correct region (dashes). He curv 1999/2002 Fig. Differen (stars), are dashed w y ere ere ∼ t GER not een b I I I duced are A BMN82. ep I y I I with plotted e B 0.1–0.4 13. a emission near shifted 4686 obtained o 1640, star of predicted third consisten of according with that c p curv t from 1989/91 for hs. ortion He the Phase-dep triangles sym These b (filled apastron A. follo es the y lies I the in and remains orbital I line He at b com on This This 4686 ols lines, of ws b relativ Figure t v (op eac I predicted curv y and the to squares). ery I with N the bining of the represen these emission, in enden en h the is IV giv argues solution to righ one es evidence observ close to orbital orbital ] Fig. e illustrated orbital squares), en a just Niemela 10 are motion 1486 t b t from simple individual authors e panels b v t: 10. (op to R R shifted y in explained. ariations ed b V V A ˚ of but cycle BMN82. efore 1979/81 phase star motion eac en fa R curv The is curv Niemela emission of 1995 v V’s et sup sho the or h b squares) b the B’s b the ( al. es the y et star, w φ y es erp data line according at of of w (filled discrepancy the +150 ∼ trends orbital on of (crosses), surface. een R SMC. of The This orbital eclipse osition star the V 0.5–0.9); et star as profiles the comp p star curv oin 1975-1979 al. v and suggested km data triangles), N B for ariations b left solution B Clearly V eha ts e onen phases (1997); of A of as to s for differ- − com- 1240, plot- w 1986 that that pan- vior star and t i.e., 1 the the b ere w ts. at to e- o , © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México what is tions as observ n Fig. authorized that ma lapping profile for function ma sumption mark that observ and ∼ tual star R cen v clusion ariations usoidal V − y 4 tempting y the troid SMC This 2200 φ shap curv con 14. w pla o w as = the is ccurs ations ed as is w as tain extrema 0.40 y e observ as He is of es w not Line km motion. of of R HD of used R lo a ell that a V v shifted V of con the cation I their role the the elo affected. w somewhat immediately I s to as − curv curv obtained ere profiles emission star 5980’s tributions 1 ed. cit cen for b template , other in resultan sp oth and giv of y use troid Profiles e of b e eculate the Since mo A referred y with en corresp star stars v v t o for and of fla black difying edg wice pro the of wn “in leads from is b w C t e the the y this ed extrema B’s not ximit at after trinsic” same star IV line = A He that = that to N. ond assumption com b φ − and discrepan to a 1548,1550 oth − R the purp the I 2600 = I determining profile. W B, y V shift, 1740 p bined amoun a to strong 4686 eriastron effects stars. alb 0.36 B λ distribution small-amplitude curv and line at ose. 1548 the and ha orn, km while profile, the (dotted in t. v e, t Ho measuring since profile A ˚ phase − The e Th tidal line, at p s V 3100 1973, w strong LBV − con in same who oin factor the ertical ev passage, us, 1 p , so this 1999 eriastron template er, corrected ts trary v φ in in tracing) km of / the shoulder of the 4 kindly WR = the in terac- terv for phase profile o from eac line- lines v as 0.05 s con- the the − as- the er- ac- si- to al it 1 h SYSTEM a . HD tic), one, eac com with He ing) the ten trum resp (star sp tral its star cult emitting UV all orbital evidence equatorial p is ha Fig. φ phases ears = ectrum v either HD along, h t I sp The T e eruption, bined I onding sp 0.36 269698 lines to B 15. o according illustrates to with prev ectrum normalized B HD IUE is to ectrum near is 5980 address motion. devise ha fourth “in still (star (a) reco gas, ab presen Line ail. whic that v wind after for 187282=WR128 the data e line o φ (O4I; fron v formed v swp53226, b t dominated Their erasing B e. = er of h w a een profiles line this are com to ted o of the profiles “in is a assigning scenario t” 0 HD the of to underlying in star con the syn resp (star of presen bined fron of in profiles ep question in HD the the profile 5980 the evidence tradicted thetic of Figure o star A, onsible BP91 t”) star c observ A obtained h, LMC). b con in C con 190603 t in (star y differen in for “in IV in closely A). whic B it whic Figure tin (WN4; narro tribution broad sp 1979 luminosit differen 11, of ed for ; swp53226 fron 1548,1550 had for ectrum, uum b or Although A+star h These y h whether in where in t the (B1.5Ia w t”, the case the is the resem (b) in lines w 1979. 12 1994 t emissions lev compared Galactic) eigh left He 1979 WR ep second y from He formed star sp el A ˚ (dark constructed o at the ble ratios. B+star I are + ts c ectra panel) at I I hs. the It the and I at nature ; C emission unless A star the line to a φ is IV consis- Galac- v line orbital w =0.43 erage in sp sp trac- from diffi- w with then eac ould cor- and and 119 and ap- B’s Al- ere ec- ec- C) an of of it h © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México sho R do flux it presen cm Niemela for orbital are (stars), The gles), con sen He are lo the star conclusion presence The He the sion line to files the gion profiles to magnitude trum almost tion serv than with He sis UV sual though 120 V y w, − the not t the I I I wing despite tin The The In for reddening, curv narro syn ed I I I with listed in w 2 in profiles the lines B ma of lev strength ligh asso fluxes the a repro line 1640, and a tensit uum 1999/2002 ts. conclusion, s v undergo sp en conclusion He ’s thetic 4. the pre-1980’s WN4 adopting els phase − y and the e elength N measured 1989/91 4.1 observ t that et syn 1 ciated w ectrum tirely of resp of wind. b The is ORBIT . I IV is in curv C the e duces ma I increase . N-abundance of lev al. y eruption star and are BP91 an significan degrees thetic ] IV caused and are con UV T this sp ect The sp of y of data the el in He (1997) strong ation able e and b extended, significan ectral ectrum b with in region, tributed y the A The He N the and and consisten swp53226 Line (op w Fig. AL-PHASE e (filled C an to I line the four effect that I cen sp v during ones, ell IV R unquestionably 1979/81 clearly IV are alues y I 2 and b V systematically of ep V en the I emission energy ectrum N y ] wind star tly the ARIA profile ma troids WN4 orbital the is and other 13. t Fluxes and emissions ionization o 1486 lines V yp the the curv giv whic w squares), squares). c formed due N it y a t w hs: through to e 1240 emission w the e. v t broad B emission phase-dep eak V en is follo plotted, not eclipse erage wind Differen C of ere TIONS ha star. primary with A ˚ es arises of h, and the v con and luminosit 1979/81 to difficult lines Ho is solution. IV phase ariabilit and v HD er in DEPENDENT lines. emission e w evidence as and b deriv are required . w the mostly tained in C e syn units at eclipse fluxes The are the v ev star that a will 5980, 1995 a Centr tend Although R alue should applicable IV in line, established. t HD with er, line-forming, this in as WN4 N V’s sup tak NL thetic ed enden con sligh sym to emissions syn y terv (crosses), and star y IV A’s b are of a TE en a that in erp to 5980 of b of e from (filled oids th ev of (in tribution comp time uncorrected supp ratio. thetic et function ep b b determina- 1718 argued al 10 tly star also us aluate t R consisten N follo t He ols efore eac star osition w sp from B. yp mo o V km in − v this een V c the than ariabil- leading K ectrum ort w 12 the e h, h I no onen to curv del repre- These whic A. I trian- w affect OENIGSBER emis- eak 1240, sp A 1986 ha star. s line. pro- The ergs this line but − the the ba- the ob- the the the b ec- re- Its vi- b v fit to er in 1 of of e- ts e, h y e t ) caution with v R N phase files the wind ingly this tion of although these significan presence N that urally ion’s 1985; plicated to frequencies; with smaller, b lar to transition systems is w sho The line, the (see con are case wind serv abilit ( the of the v bl ecause V as bl GER IV IV most ack the N determine orbital wn tin ack The The winds, R absorption idea v ed generally line star ] ] also b , e.g., on ariations effect V of y V eac is b and con eclipses. t 1486 y 1486 of no uum-emitting ), corresp Auer explained star. w ). dep oth in in to curv in shifted phase-dep lik single is o the h P 4.2 of of (Willis of R tin is and pro star t ep noted of N Prinja, HD teraction This eac line the V endence; probabilit data necessary ely pro motion departures the A ˚ an A) ˚ Cygni “in the a of . o uum IV sigh e Lines vides the a maxim & c v relativ Char h of v also onds h-dep whic 5980 duce ] ariations the the A. saturated fluxes and ep b wind transition stars, bl fron trough, eclipse larger 1486 is Ko star set. t ecause along star b stronger ack et o with pro y Barlo to Wind acteristic c illustrated absorption enden dominan arising wind the h enigsb phase b alone. t”, h um . and al. only Moffat ely endence effects , significan ecause the y B eclipse A ˚ duces con is is the region. ho In dep , it size from wind while the b when and most b 1979; remark the relativ the w, dense bulk w y sev curv is t tributes a ecause eclipses b eclipses to endence and dep erger con ev eclipse flux probabilit from eha eac m and & The relativ maxim v within t as distortion strong eral et er, the it eclipses. ertical the ultiple at Wind they es but it tin factor endence reliable wind h Ho t vior Ko with wind ely b ha lines v able. al. is No is when brigh ariabilit oth φ 1994). wind resonance predicted uum of UV it other phase-dep w v slo enigsb o sho “in formed on ely to less e ha are arth (1989), um is ∼ ccurring (similar the these of absorption suc V sp w the in stars causing scale system, y a pro N v a ws elo tness line-profile fron this the 0.0 est in emitting e eed straigh N of measure He more (similar exten affected of h WR+O star semi-forbidden flat is V binary terpreting 1990). cities erger vide y dashed already a V The the effect the has, t”. lines, wind in significan p I line is only v absorption, to motion ( I has supp endence ossess transitions of p v A ery to at t most similar is ∞ HD ortion the ho tforw compan- Extreme informa- line of coincide star p in & surpris- φ profiles ) that lead to a mixed, at ossible binary b w strong In in in region orting unlik of is =0.36 whic curv along 1986. y Auer large com- ev b 5980 v stel- that pro- nat- line due ari- ard een A’s the ob- the the the the v tly er, to to in ∞ of of h e e © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México a the b c detector fitting Lo R In Vs tegrated w table 14112 14166 disp are 11190 11175 37768 37759 37781 15080 15072 37788 42702 42446 42711 42721 o2070 o1020 42470 42694 o6070 54490 56223 o5070 53226 52888 56205 o4070 53216 53185 o1070 54671 54064 55955 55380 56188 56017 o3070 55394 53036 55932 55315 53129 54727 1598 Sp Gaussian 4277 4958 4345 in ec. head the ersion c c c all fluxes cen observ (no 0.60 0.48 0.44 0.39 0.55 0.85 0.80 0.61 0.44 0.83 0.49 0.54 0.01 0.99 0.05 0.39 0.40 0.32 0.43 0.36 0.43 0.51 0.99 0.15 0.38 0.17 0.86 0.36 0.89 0.99 0.40 0.83 0.40 0.05 0.50 0.39 0.83 0.78 0.86 0.82 0.57 0.68 0.91 0.53 0.82 0.05 or sp troid ectrum. φ correction (10 Loren ations FLUXES − of 12 1600: tzian the 1160 1310 1210 1210 1020 1100 1170 1080 1290 1320 1060 1100 1285 1100 1000 1170 1170 1100 1630 1170 1060 1020 1040 1030 1005 1180 1200 1190 1050 1090 1100 1110 1035 R 500: N 990 920 920 950 940 990 830 LBV erg · · V np np after · · V a · · line, for profiles; cm 1240.83 / AND WR 1981, SMC − in Flux 2 32.8 16.1 15.2 29.9 44.9 34.1 14.2 40.2 27.9 18.6 20.7 28.2 26.5 17.2 19.7 33.1 36.4 17.0 20.1 30.3 14.7 19.0 23.7 19.5 28.7 31.4 27.8 26.3 30.2 13.9 30.5 10.1 14.5 11.2 36.3 km T 9.5 4.7 4.4 9.7 3.5 1.1 12: s np np 31 17 SYSTEM RADIAL − ABLE motion); and b p 1 eak ), s − 1 not th , in R 323: 465: 460: 342: 141: He 328 278 145 284 237 222 134 190 253 250 160 239 323 131 189 283 128 140 213 100 150 261 275 203 223 195 270 360 296 120 112 120 145 140 225 100 us with · · · · V 2 tensities 93 · · · · corrected · · a · · np I these VELOCITIES I HD 1640.47 resp indicates Flux 103.0 105.0 127.4 136.8 119.8 111.1 110.4 131.7 155.5 102.0 105.0 105.6 5980 v 50.0 44.1 72.0 83.4 62.8 93.8 74.2 88.8 81.8 78.8 98.7 79.0 86.4 90.7 91.2 99.3 41.0 41.7 55.1 87.4 96.1 36.9 70.8 69.4 ect of alues 100 · 55: 14: 19: 48: 32: 30 63 41 · N b · for to V line are the reddening, and R 420: 280: 200 216 125 180 145 110 117 120 140 130 240 150 125 210 180 390 110 100 110 160 300 150 130 340 np: · V lo np np np np np 30 30 70 70 40 37 82 99 60 80 80 80 60 not w · · a N He w a v er IV elength presen I I limits. ] saturated 1486.50 obtained t. listed Flux 29.0 25.0 31.0 25.0 35.0 35.1 34.0 14.9 26.4 17.9 15.9 15.2 23.6 35.0 35.0 24.9 39.0 34.5 15.2 17.5 15.3 15.0 16.0 12.2 27.3 46.3 39.2 46.6 12.0 16.4 16.4 10.4 24.8 26.0 16.8 11.2 · np np np np np np np · 1 1 b · the b in y 121 © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México He Fig. 122 differen 1979 tion: represen izon concluded (triangles), or zero system. (Georgiev b exten cause tion − con len larger − mon teristic wind. slo (Ko s − time − et 2600 1100 900 1 w t” I “step” w ) tin V tal I enigsb er ths een where 1640 flux alues prior of b t 16. 1979/81 of motions uum, km than elonged t sp lines of km to t the v follo the sym The 1979 elo v eeds A ˚ lev the erger s black − of to & ( that and s − eruption, the v (top) generally cities b v apparen − Orbital mark 1300 wing els, 1 shoul bl v ols other Ko the 1 ) absorption, and (crosses), edg (from ack , to within 1999/2002 for edge absorption the and et enigsb corresp but and e der eruption , star some the km w 1991, C measured and winds’ al. ere fast t ) IV c) phase C ∼ ma v significan yields decreasing eruption, elo in s A. the IV erger 1998a) onding − v 1548 of − is iden 1989/91 y Ko bl ( 1 cities the 3000 (filled 1548 ∼ In , ack b b the v v (1979–1991 sup line enigsb edg eliev e b) dep alues v tified: A ˚ − this 2004b). elo on visible absorption at c 3000 e A ˚ to ersonically at an tly suggested km haracteristic endence , w squares). profile cities ed three 1979–1995 (b (op trend − defined the ere section all of erger slo edge ottom) 1700 s to a) km en − v ep ep as presen w 1 bl that The reflect sets o in er o a ack squares), data). in to et c s a c at km of hs. − h as Filled this tersects shoulder edge ( plotted line a “shoulder” al. ∼ 1 − expanding are of maxim are of − ) t. IUE v v the s 2100 trend The elo − edg 2100 − observ wind (1998a) “turbu- c conclu- K ∼ A sp harac- profile In 1 400 not circles OENIGSBER cities. . e t lo data 1995 eeds 25% with hor- Be- um the the the km ca- for to at to to at in a- of trend C bital ties when lev at els this s s ev are to in B rected HD lo ren HST b sion line near Fig. − − et cit GER IV er, 1 1 are, c 1979/81 − el. w tly all ). , A of hanges profile most measured y een time. 17. 2200 5980 the suggesting is sp the 1548 phase-dep scale sample for v star for ep T the re-examined resp bl ectroscopic The 1991 ables eclipses Line ack o actual km a the lik is c in most and in hs B cannot ectiv (referred , more ely sho 1979 horizon and v profiles s the SMC is 3 of on shoul − after enden He that (0.0 1 origin wn ely and asso lik “in the 1999 eac and (swp4277, exten extended I , der b data. ely motion I and in tal e 1981, in in the ciated h to 4 fron of t 1640 C , v unam (dark of wind of v list Figure ∞ t the and the the He IV 0.36) ariabilit dashes fast t”. of the These (B) the I illustrated A, ˚ the P (assumed I ligh λ v ligh ranges biguously also lines), v the sp edg edge 1640 ∼ edg and ∼ 1548 individual This Cygni resp 14, eeds t t v − e data − y e mark adopted alues tracing). , with of 3000 an A ˚ 2600 around consists with sp compared ectiv comp plotted v trend the at for elongation ∞ eeds imply line to established (A) in star of km the orbital to ely a stars b more onen sp e the of Figure con systematic − profiles . is φ s primarily ectra, ∼ +150 that flux on B. − 3100 1979/81 with The = presen tin 1 t), v A − recen phases (0.83) edges elo Ho a 0.36, 1700 uum cur- cor- and lev- km km the 15, v or- for w- ci- at of e- t t © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México and of ∼ tain 1989-2001. while for ence (C 1989/91) is only tion ep b phase. fixed shifts line near φ panel), where Fig. et o ∼ the 150 w eviden IV In c 3 ties profile een the hs 18. the data in displacemen 0.0 b , in ep at data. et 1979/81) general, the The km v of the are 1991 o eclipses v w edg the Line and t φ c elo ∼ een observ are hs in e C phase s with larger differen ∼ − cities − v (C 1979 and indicate ertical IV 0.36 1 profiles 2400 a 1979/81 0.9 v (0.0 the IV for t ∼ ailable ations. line 1999 the − b in (swp4277, (up of ) is et − t 1.3, km terv is v and scale measuremen w sym He 3200 edg sho of plotted near to een former (dark v and s al edg e for I 0.36) v N − wn. Unfortunately b I ∼ edg , w 1 in differen ols 0.5 km V e . dep ere 300 ep the ligh 1989/91 lines), e ∼ Near 1238 C − and corresp as In o s ep ∼ ending 0.9. applied IV − c − t km t h a 1 o t t tracing). w Figure 2700 − , A ˚ an c function φ while ep 1979/81 compared o h uncertain 2400 while s A at − elongation o = ond orbital (op sho 1  c mark on hs. , except ) orbital 0.4, 200 high for LBV v en 16 km wing to the edg the No of ed (crosses) the v differen squares) (b km with ties e shoul s phases, / qualit relativ resolu- orbital for − uncer- phases ottom (C differ- WR (0.83) V 1 data s edg are − IV the the der for 1 y SYSTEM e e t , , corresp 0.8. at φ The all suggesting fast at are is (star is ing 2001, for that tiv do v s tected, 1991). b and Fig. φ phases − alues ottom = = the not 1 es differen ely φ HD phases the , Unlik F V p the 18. 0.36 edges 0.0 19. rom P ma ariabilit although erplexing. C), , ∼ not The the case, supp the ( near slo onds 5980 Cygni − y panel as eruptiv 0.36 (star (star e − the 1850 Line w b pro winds t He except ligh C 2600 ( that illustrated e osed er then ep ∼ φ to y reac IV b are duce I B v of o A absorption = I t ottom − there profiles with km edg e c , sp 1640 “in the Figures hs, (star to tracing Fig. of 3100 in an He hed 0 phase) similar during ectrum e s a (star the ha fron fron observ for explanation − fast I orbital A ˚ is I 16. panel saturated is 1 v B), km ) is with of e and t”). three three t), a that prior 17 wind A c km sup 1999, not Its to swp4277, and tendency Si hanged comp ed s 0.36 “in N Same of − and phase IV the erp mean those during s 1 in differen stars a V − to Fig. − ) arises φ fron 1 1393,1402 resonance onen subsequen (star osed 1240 2400 observ (i.e., 18 . is blac the = sp its Ho of v 16, needed ha observ t”, ectra illustrate, obtained 0.36, alue for the ts in t eruption k P v wind (star w v B on v bl orbital one e ed left ev bl for Cygni star circles slighly ack in ep v ack is as A ˚ eac er, since ∞ ed in t line to o conclusion fron panel) A; − all structure. in is ) ep c at B. ∼ h 1790 the hs in 1979/81 in accoun absorp- Figs. exclud- phases, profiles not o resp ep (1979– − t) profile in star orbital and If c larger 1989- 1979. 1979, hs 1700 o v this and 123 and the c km ery de- ec- hs 17 at B it t © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México 124 a  V Sp 100 1989/91 1979/81 elo ectrum 1995b 1995a o1020 o2070 o6070 o5070 o4070 o3070 o1070 56223 56188 56205 56017 55955 55932 55394 55380 55315 53129 54727 52888 53036 53185 42721 54671 53216 54490 42711 54064 53226 42702 42694 42470 42446 37788 37781 37768 37759 15080 11190 15072 11175 cities 2002 2000 1999 1994 km 4958 4345 4277 s − corrected 1 . − 2400000 52386.6 51655.1 51315.8 51314.9 51310.8 51308.9 51304.8 50045.2 50033.5 50036.4 49986.6 49978.7 49975.6 49930.8 49928.8 49916.8 49706.5 49859.9 49680.5 49697.5 49712.4 48544.4 49851.0 49716.5 49831.0 48543.4 49784.1 49717.5 48542.4 48541.4 48515.6 48511.5 47871.4 47870.2 47868.2 47867.2 44870.5 44634.6 44869.5 44632.3 43981.0 43928.6 43921.1 HJD for SMC Phase 0.99 0.01 0.40 0.36 0.15 0.05 0.86 0.43 0.83 0.99 0.40 0.99 0.83 0.50 0.40 0.78 0.86 0.82 0.51 0.39 0.17 0.54 0.36 0.38 0.32 0.49 0.89 0.43 0.44 0.39 0.05 0.83 0.61 0.55 0.44 0.39 0.85 0.60 0.80 0.48 0.68 0.91 0.57 C motion IV K 1548 OENIGSBER − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − (+150 V 1800: 1650: 1700: 1800: 1780 1770 1720 1740 1660 1730 1780 1800 1600 1800 1700 1700 1900 2000 1600 1700 1800 1700 1700 1900 1900 2000 1800 1800 1800 1900 1900 1800 1900 1800 1800 1800 T black · · · · · · · ABLE A ˚ · · · · · · · · · · · · · · km VELOCITIES V V elo s shoulder 3 − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − cities 1 GER 2230 2260 2170 2260 2170 2170 2250 2300 2200 2200 2300 2300 2400 2200 2100 2300 2200 2100 2300 2300 2300 2000 2100 2000 2300 2500 2400 2600 2700 2600 2500 2000 400: ); · · · · · · · · · · · · · · · · · · · · uncertain · · · · · · · · · · a − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − 2300: V 2420 2420 2960 3230 2440 2300 2440 2900 2800 2300 2800 2500 2700 2600 2500 2400 2500 2400 2400 2500 2600 2300 2300 2300 2700 3300 2600 3000 3200 3200 3300 2800 1770 2500 2300 3000 1740 2100 2500 edg · · · t · · · y · · · e in IUE em em em em em em em D data A on on C on on on on on Commen blue blue at is blue blue blue blue blue in − 2770? general edge? edge? edge edge edge edge edge ts © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México a b c d  V “em” Uncertain Sp Here 300 1989/91 1979/81 elo ectrum 1995b 1995a o1020 o6070 o5070 o2070 54727 54490 54064 53226 53216 o4070 54671 53185 55315 o3070 56205 o1070 53129 53036 56188 42721 55955 52888 56017 42446 55380 56223 42711 55932 55394 37788 42702 42694 42470 37781 37759 37768 15080 15072 11190 11175 cities 2002 2000 1999 1994 km 4958 4345 4277 signifies the s − t measuremen corrected y 1 , Phase in dep emission. 0.99 0.40 0.36 0.01 0.82 0.32 0.89 0.43 0.38 0.15 0.36 0.17 0.78 0.05 0.99 0.86 0.86 0.39 0.83 0.54 0.99 0.51 0.40 0.83 0.40 0.43 0.49 0.83 0.50 0.61 0.44 0.39 0.05 0.55 0.39 0.44 0.85 0.80 0.60 0.48 0.68 0.91 0.57 · red · ending · for wing v t shoulder SMC refers − − − − on − − − − − − − − − − − − − − − − − − − − − − − − 1400: 1000: 2100: 1300: 1700 1800 1100 1200 1300 1100 1100 1300 1400 1700 1200 1800 1700 1800 1300 1600 1100 1800 1800 2000 1700 2000 1800 1600 placemen the · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · motion to · · · · · · · · · · · · · · · c He S/N. LBV the He I I − − t v − − − − − − − end I − − − − − − − − − − − − − − − − − − − − − − − − − − − (+150 / elo 2500:: 2600:: I 2600: 2500: 2600: 2600: 2600: 2500: 2500: − − − − − − is WR v 2600 2600 1500 2400 1700 2100 2600 1600 2600 2400 2600 2500 2600 2800 2800 3000 2800 3000 2600 2100 1630 1900 2600 2800 2900 2500 2600 1640 edg 400 400 400 400 400 500 cit em of  e T y 200 SYSTEM a a km ABLE A ˚ deep VELOCITIES km s 3900:: 2500: 3300: 3300: 3900: 3300: 3000: 3300: 2800: − v 2900 3600 3000 2800 2900 3100 2900 2900 2900 2700 2900 3200 2900 3300 2900 3200 2900 2600 2700 2900 2900 2900 2900 3000 3000 2600 3100 3000 r 1 er · · · · · · ed ); · · · · · · 4 s · · · · · · c p − D ortion 1 HD A Emission C and FWHM is 5980 1900:: 2600:: 2000: 2000: of 1300 1500 1890 1550 1200 1380 1590 1200 1950 1500 1450 1190 1180 1760 1310 1450 1380 1150 1380 1570 1360 1620 1520 1620 2330 2090 2350 1590 1100 1400 1300 1440 1430 2590 1870 2320 2150 discrete in · · · · absortion. · · V edg D D v.wk. v.wk. D D D Commen e absorption A A A A A is Cs C C C C at at at at b D D at et A A − − − − ts w − C C 800 1300? 1000 800 een b 1300 at at comp − −  and 1300 1300 100 onen − and ts. 900? 125 © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México ticularly natural raises dep when the star km flux maxim He eruption narro (FWHM), φ (due emission He ep swp55380 nearly profiles. dep emission, is sion v that b conclusion with range 0.36–0.9, en and teractions ( The ther b a could quan obtained v con maxim He tion. 126 general, v shoul ery e e function = edg tly o listed 5 asso almost I I I tribution The The The c endence, endence, line I I I s 0 A 1.3, con hs from top e tit star strong, b − an w to In der emission 1640 absorption v sup the also 1100 oth the ∼ 1 um um is ciated eiled iden y is when (Gaussian extraordinary tained result last profile addition, origin with star maxim The appro in panel v eviden − reac ( attributed sp v from A erp (He the con edg v star stars completely (i.e., ( edg wind lev measured − b A ˚ 1700 of exten that shoul tical φ ectrum column or e column but 3200 b e osed the hes e tin from FWHM el except the A) orbital with full = ( I conclusion y reflecting no of ximately I φ A. star He in in ∼ of comp corresp ) t um a der A star of uum-forming sp the t km 0.40) He a = general the during the has − ww flux whic the Fig. star significan comp With km width on it I FWHM of and eed comparison to the 5 “half I 0) star 2400 ∼ B. I 5 exten is exten s narro of ma onen fact I B The c b electron phase 1994 con the − the line a is ∼ s − eclipsed. y is of h B. red 16 for and star b T not onding − 1 B T emits . onen y 1300 ) resp efore narro fitting largest able effects C. 1 − 1995a, to larger. able tin trend pro Because maxim at t T that p t seems . broader flat-lo t b is b extended w the is 1700 able ossess wings ∼ of exp e This et ha when t ( − swp4277 uum Therefore, whic to t. a v vides ect half-maxim lo emission scattering. asso w 3000 4 ep 900 r the a to w 4 ving v w He plot region ed w the primarily ected een ∞ b for a lists er v due lists km ards in o when oking Although 4. In est, um” to inescapable ) et This − further h ery Gaussian c lev red ciated I strong km within has this h w w I w 2000 enhanced line 1979/81, underlying km smaller the sho a the orbital the of The s forming e as el een, to v red and or the − broad to emission (1979) of measure edg s the to ha b v correlation the 1 ws s − at p lines slo measured line wind-wind edg phase-in , een orbital profile − the ha orbital star km 1 ortion v um e only giv v supp He wing p for He 1 ) decreases to the e v w a alues e , sup (He v ositions red r emission FWHM this phases er to concluded consisten e attained). He en ed minim (He I is s the v when I example, from B region in discloses emission I − that I a elo wings, v orts with wind, erp the K ≥ I profile, 1 that tensit 1640 1640 is elo I should appar- whic phase- of strong of I of ) of I terv phase latter OENIGSBER ) I emis- cities 2600 I osed line. ma par- cit ) and and line is the um the the the the the the the 0.9 in- on ei- at at as at in h, al A ˚ A ˚ in it is y y y a t near disk for ing or timescale 0.40 find & whether pro in that stellar b abilit ously second mainly P lo Si region. and and con suggesting there plotted can ducing other eclipses v wind in collision φ s the in are strains gin sp in question than − ∞ er w-lying 5. GER = eed, 1 IV Cygni whic full Ko the Fig. due tin duce There Similar The a due of t to except of v sp b THE strong of w , is p 0.0. the φ y shoul 0.36 e significan enigsb of sho p is uum UV ermitted o as eeds view UV. note, disk v =0.36, the asso h and in to ossibilit 14, established. star; the star asso to HST that edg evidence with a the line-profile star rapid the sho absorptions remains, wn sho One der excited v WR+O sp v R in are “turbulen remark e companion; ariabilit that a c on ciated ariable sources, of are v that absorption OLE of ciated erger hanges effect ectra c ho B’s wn , and ariabilit is emitting ∼ ep (Auer timescale sp k no A the one consisten at the the p w t y c observ o not ectra cone − lines hange the ossible ev in c b amoun wind, the is (3) relativ least p OF hs 3100 able rest atomic 2004b), mak ecomes with star is ho observ binary er, op oin with turbulen y that Figure & observ in difference rather t” Note v due suc y w “turbulence” in wind-wind wraps en at ariabilit ed WIND-WIND are arising ting of region that es Ko the ev in c in is motions, three (2) for km star is t prev t hange explanation h the e φ the star the end in to er, it er with o of enigsb v p also lev as v lo systems = that N ed dominan wind cculted edg to the wind v olarization 19. optical ertical Villar-Sbaffi the than s t at wind calized en ery B. the of around profile ∼ − 0.36 V els. w 1989/91, is of A, in motions. y: at e in 1 ting presen ards a in all in 1240 wh v − But these ww teraction blo b Since difficult the erger ariabilit is eclipses UV large eclipses instead orbital (1) there collisions. et transitions 3100 in The wind and of the y phases b c c w He shift, v in is t, remains it star k y “in the a the ery sho and sho een star star ph is ed line-profile COLLISIONS t, t v the resonance 0.40 1994; exten Si more I flux the from degree w km since measuremen ariable. I is structure ysical that but c It c b o limited fron ∼ y strong. phases lines B to IV of φ et k He in k can y and B. except little B effects wind profiles of is s wind-wind cone =0.36 − illustrated cone. as v the determine bulk − whic al. t As absen 1400 constan ariabilit attaining extended t” I Georgiev and star once 3100 in 1 I b < accoun of of p eclipses the though et 1640 sp terest- (2003) ersists stellar of doubt previ- of 1 effect F other n short h w v wind v lines near con- that eeds A ˚ pro- rom um- B The An- edg and t da ari- ori- een the the the the km are in ts A ˚ is t, is y y e t © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México stellar role fects: winds abilit c sho v enclose displa wind cone the wind (Fig. ( Fig. M haracteristics elo ˙ A c The observ cities pla ks 20. w = y eclipses. 13) y collisions alls are (a) ed 1 ma winds the y are wind-wind Shap × ed er is b in indicate y 10 expanding, it wind y kno b is b consisten − y e HD N breaks e 4 (assuming on Ho the of , wn. of made. V 5 are material the the w × the 1240 lo ww 5980 ev 10 in cations Ha difficult left ww the er, − teraction t c t w 4 a ving and with in , c at o the side that and preliminary spherical that sho pro stellar whic for He p established that c 1 of ducing oten is to k × whic they I has the h cones I pro 10 predict, winds 1640 tial star exp − h jected figure. symmetry four 3 are line-profile tangen M under ected analysis effects A ˚ A

and the p LBV in in and yr on oten unless trinsically tial − to the HD from range the of 1 / ), tial star the of of WR v wind- thin and elo 5980 v ww ari- the the the the ef- con cities of B SYSTEM c M sho ˙ tin B c uum-emitting = k w ere appro 2 within ac along spherically lines (d) sources ma ization winds. (Georgiev (a) phase × hieving computed, 10 y HD and p ximation − b that ortions 5 e the dep 5980 M structure its of Eac gained (b)

v cores are enden sho X-ra & ∞ symmetric); yr accelerating h some ; ha for of − Ko one c (c) sup 1 k y b v of . the t three e y enigsb The emission cone of of the erp the of v using b ariabilit whic een sho the osed these differen p t v w alues w erger ost-sho (b) c o h alls incoming, incorp k the region stars are on that cone it effects y t of , simplest ma 2004b). ma sym listed. the c but star orated at k can y prev y are material b φ stellar truncate pro pro ols A’s pre-sho only = mo The exp en along duce approac duces 0.36, in Some mass-loss ting dify ected to dashed wind the that c the the assuming emission a k the it orbital- insigh h effects stellar mo to sho lines; flo wind from lines p ion- rate 127 del os- ws b c k e t © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México HD Fig. 128 lustrate absorption star lution mation). equations M sible: lie v ww lo that terminal along braic cone cen that lided. folds; 5 illustrates ues deduced 5.1 ˙ ∞ ws × A (A) v c tered Can . 10 A’s 5980 ery of = flo 21. the w sho a Ge expressions i.e., these the − The alls of = precise ws t´ star 1 con 4 ometry the close o, c × , wind t 2000 the on k sp at Under w along Geometry of t 10 and the and the comp tin angle Wilkin, w o surfaces eeds, surfaces. columns differen − A’s o Can the conserv sho uum-forming 4 together km star v determination winds configurations the 1 elo of onen the M c × these t´ θ star mass-loss k o and s for

tangen the is − cit with 10 t & et surfaces sho 1 ts and ation of measured yr , of y orbital are − the around Raga v al. Wind-Wind co assumptions, − are 3 (i.e., of c ∞ the wind k 1 the oling the M (B) , assumed tial (1996) lo star cone region of pro

M cation rate orbit ˙ (1996) phases. that w the tangen = energy v B yr material of for duced. eak whic elo A is in w 2600 − = the and is alls thin (1700 ( 1 cit efficien the three er separate and M ), R to h v 2 ˙ Col find tial y alid, × wind. A ( km geometry after in and and the Shaded the θ reference collide v sho 10 P ) ww pro lision t whic = km arameters assumed ( flo − s of t simple θ analytic − and c momen 5 the sho c ) ha jected k enough w 1 1 the the Figure of h . s M region ving appro − × v c areas at P R K slo this the

1 k elo e of winds ) frame sho Cygni OENIGSBER 10 gion their alge- cone w yr tum on out- cit v col- the gas − are so- est xi- al- al- 20 − c so il- to in 4 y k 1 , corresp s and φ side wind cases, loss ww Fig. km ev M of ple example, cone R at ing the 31, bital the star truncated Th b − ˙ e B GER 1 en B = the us, p c , large The of s eccen t a corresp eriastron the rates, M = of B’s = − for 22. w 0.4, more is and ˙ phases. c 1 whic o B the onding the its hange figure. 2 , 15 exp M ww stars wind where p = × ˙ enough extinction tricit Represen the ossible the eruptiv A b and momen ected h R 2 so line-emitting 10 c onding y × =

is sho − 10 if t the in v c stagnation to The to , y w 1 hanges sho 5 Other the elo v × larger − M o of ∞ to c the M 56 ˙ 5 Decem e for 10 k ww sho tation cit tum stars wn (B) A M ev relativ the b observ

cone to − of e R y 3 ww c

= the en c yr large. in parameters

k v star la = sp M as orbit, geometry yr balance t. b ∞ is − 1 w, c cone’s wraps Figure

at of er ectrum − 2600 1 wind region e a (A) er p F × illustrated sho , 1 yr oin A’s lo these or , function the 30, apastron. t is 10 and ypical − cation the c are star t 1 km k placed − around con limiting , to geometry is 1994 c 21 4 and of cone v hanges distances swp53226 separation on assumed, ∞ in ha tin are s B, M for − of (B)=2600 star of of v v uum 1

fa 1994 (swp53226). for w ∞ e . geometry WR-star at v the R Dep v star e phase, ∞ yr F (A) attained presence. or A from B assume differen or the of (A) − b ww ending = Decem of migh 1 y B. migh an = the is . HD b star b km c 21 star = et 600 This 30 imply- sho exam- ottom Giv sho . three w t mass 2000 t t 5980 that R v s F not een R b wn B’s km − or- ∞ on A A, b en c

or er is

1 k e t , . , © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México tion lifting He b olis culations diativ vicinit tron) star on axis p that exp shap R s 1998b), ure there in eclipse v diativ R v orbital lo v are t v erably and migh v to in 10 strongly profiles within mate With s this the w − − alues t ∞ ery ery y ears 0 0 cities ( 1 1 o Fig. , θ a (B) R the Figure I the Coriolis The The ected is ) I is temp forces are and noted. v B stars, and b stage, 5.2 e ∗ < t p that large the w 1640 w e e y (B), ab of is to the merely not y osition of is b ind the eak sho of narro 20 v the as = 1000 . α forces. core braking” M e differen w uses o elo still of v the line-of-sigh M not on b ˙ V erature R the He v to sho degrees or ere ˙ v exp correctly e sp 2600 A ob indicate is c is A ˚ pro e where elo α B 22. mass-loss ∞ A ww giv cit k, N star observ b forces the a the w eculated b The = the I sev emissivit of jectiv emission km predicted wn ∼ . a = cities I the sho V ected, = = on ∼ y duce computed, e and strong er en c tan large line-forming 1 Indeed, F t star of sho erely still 360 km 1240 surface sho × B 3 The wind in 48 2 or in s c the sym and wind the effects with maxim × line-of-sigh − k ha ed − one 10 e th R lo c are a 1 Figs. represen along t 1 10 this c the s km cone k R of v

accelerating. us, a A, − cations k − effect. p b rotation observ distorted rate for line A ˚ e ( y scan in comp parameters densit

− 3 cone line v 1 star ortion v ols simple resp (p densities also cone determining elo exp . 5 without or along the M hence s that line cases of § case, um (from (Ga all − 20–22. eriastron) b near M the and The profiles t along of cit

/ 3.3 1 that star with ected ect op onen , b v ed a ted fact y

ww yley region surface w for yr y in v een α t v star “radiativ of Sho . ening ailable ind alue structure the of calculation to as illustrated to giving yr some sho − in emission-line v the ∼ w F Ko c B, in this t elo the resp whic WR 1 the are T that the or neglected 12 − ), e b ck exp , the swp53226 regions to et A, o where this sho of c 1 F used e enigsb where b v cit stagnation ◦ k of where v urthermore, is angle to first ∞ sho eliev Cone . the the ect largest. al. (assumed), b ww sp w ab h inclusion ected of but axis wind v information cone y c the rise e (A) ind e v not figure t k tangen 20 ectrum. o c t braking” and c 1997) to these strong, of for v ( cause k w e LBV corresp order, regions. erger ww θ the closer e at = in sho underlying joining and of a R Wal v b ) cone to = in the truncated the is pro giv v or the elongs indicates

1700 c elengths this dep φ Fig. profiles. an b the 600 c b the wind / consid- a tial en k ecause on effects ls (apas- v in jected WR other, of p of ∼ sho is et Cori- alues w wind lo than onds oin cone ends th esti- “ra- The and line cal- alls the ap- the the the the fig- the km km v ca- 0.4 20, ra- A on al. us c to e- is t, k SYSTEM t co kinetic regions, w emission as sivit the b corresp b simple p large only en con transitions, in already dep motions that phase. no is that star absorption are primarily the with of of iden ww while cannot conceiv orbital significan are is, and ho of ww ecause e ortional eak tensities, ordinate tire o these imp the the HD r indeed, c c ww asso tribution In Langer(1994) 6. ends d. t tically differen − y exp case co A. emission w er concern densit the ma 2 the p of EV Figure ortan o the oling c SMC red observ able motion ond 5980 Except ortions wind densit ciated accoun energy once ected The y profiles the emission sho the the men B strongly of N t OLUTIONAR arising to , X-ra arise HST line y region half p mass-transfer IV ho system t as t c that ∼ to than temp and ossible function, (+150 ww N simplest ks profiles (star tioned, the v from is ed y from 23 to ] ma w to w t with long ys. 500 of that IV of radiation 1486 for ev of the ind distribution that c of for with in profiles, only note these y line it from star ] found lo erature v er, sho the is are on B, near con ary the 1486 ww the phases Ho the cal km the is w the km is ∼ as to ww of predicted A ˚ are form are c a the in features regions stellar A this cen w profiles tribute, assumption k that c a v lines v and effects densit line asso the this wind with observ c emission elength ww s ev that en s ∞ actual Y A ˚ this region and the emission, line − − highly at in tered primaries emission, of energy particularly ). er, tire 1 1 ST the line near c ) ciate line ww profiles the b optical/UV arbitrary star’s the are arising v case), for stagnation y assumed in winds. oth distance. region, densit A Since clearly the at ery ed of on emission-line as TUS for ww c profiles of is emission w on range HD asymmetrical, ww gas the the large assumed. is as angular originates the a of at the massiv assumed line of main c wind. N these but is function the the y c the in do corrected for less assumed con the sho 5980’s OF φ elongations, these IV from Th asso ev extended that densit extended (whic θ units o binaries profile if here. densit = ww not ] are v star en tained c example, actually us, conclusion origin w collision e er HD k Hence, v p line affected “turbulen ciated 1486 momen a The elo single 0.36, oin c cone the under v to p quan h whic compared exclude neigh y the Ho of since from elengths, profile. with ermitted emission cites. 5980 y v t falls b profiles profiles This for cannot orbital elo A. ˚ within w ev actual excess of and w e wings wings emits emis- h tities w since stars ev emit with ould it b pro- tum olv cit and 129 alls our the the the the the the the the or- As er, off b t” It is is is it y y a e © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México ion significan b than et (Meynet and with P ble. starting 130 et etro al. w affects Rotation in een observ in vic 2000) ternal their to & et tly mass ations its Langer al. pro and differen single-star rotation has rotation 1994; duce transfer th (W a us, 2004). ma t results ellstein, Meynet 2001; et Ko and rier aa ev on if Sp Sp Sp V V T L v M N[He]/N[H] v v R e R a Orbital P P R V V M V M V jor Abundance prop ˙ ∞ ∞ ∞ and coun r r ∗ or arameter olution al. StarA en StarB StarA A C (eruptor=Star (system) (Star (Star enigsb / StarB StarA ot ot the (Star / ectrum ectrum ectrum R (Star (Star (Star the b R vStarB M 1991; effect In sin sin 2001;

(da starA that

erties, terparts. / j stellar /R / presence Langer, & / / Georgiev this L R B) C) ev M inclination M yr erger ys) A) i i C)/km B)/km A)/(km

/R

Maeder / (km (km

olution − in

(Star (Star (Star on ESTIMA R ma aa ( 1

section, ◦

b h ratio the K) one Non Niemela stellar S. et rotation y s s = − − & C) B) A) s s The & Duffau, of A) − 1 1 b al. − − s 21; binary ) ) Braun − L 2000; ma e 1 1 b are Ko TE 1 a y TED 1998b; compared ) the ev in y compan- enigsb n et negligi- K um terpla olution d exp 1979-81 is 19.2654 53,000 Ko Heger adopting 30–40 OENIGSBER WN3 WN4 2001; ques- stars − P al. 3100: b − − − just 127 ARAMETERS 7.3 enigsb er ect 28 50 86 15 21 erger · · · · · · · · · · · · 6.3 6.1 5.8 0.3 T · · · · · · · · · · · · y ABLE f b b b b b · a a a a a · · · · · · · · · · · c (0.63 Ko 1997; B erger 2004a. enigsb m-M 300–1700 3 1 21,000 35,500 > b . × 5 star b made ary tion WN4: y 5 10 − − I c 1994 160 e 500 280 10 10 1. 2. Assuming 8.6 = 8.7 0.4 a et GER mass); − erger · · · · · · · · · · · · · · · + addressed, 7 · · · · · · · · · · · · · · · 6 3 status 19.1; d d d al. · · · · g g g · · · · · · · · · · · The In resp sp curv e e e e e e ev of and OF ectiv olutionary 1978, HD 1998a; et ectiv es curren HD the i al. en Ko a ely of 5980’s L Breysac unciated. the ely starA 2000; enigsb , Niemela parameters 5980 and 21 t , e stellar Decem masses 50 trac p and 1740–2200: 2600–3100: ( the her 1999-2002 L osition erger and

ks g )=const et WN6 15 Drissen constrain b & WN4: 1700:: − As radii O4-6 250:: − er are 7.6 et of al. 28 adopted P · · · · · · · · · · · · · · · · · · · R 75 6.5 · · · · · · · · · · · · · · · · · · · a 30, on er- al. d h

· · · · · · · · · · · · · · · · · · · f j i star used. (1997). of first M and the

star ts , A step, H-R based the are The on A and and the visual its diagram non-rotating assumptions star on ev follo B olution- the are, brigh B wing: are, will R re- V t- © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México ww Fig. 2 s N bution slo − × 4. 3. IV 1 w 10 c , er ] The F and ness p visual and m to tended m is E the to the sp based and in subsequen affect − sho 23. compared 1486 rom ossibilit 5 than ( v v ectiv from adopted B these rotation the ( ( M c C A R assumption V k is ratios luminosit ) ) a

− A ˚ C ∗ the the on magnitudes 1000 region, = ely) SMC Predicted assumed = the en yr v reddening = V in parameters. alues y − 12.79 v the t ) radii 12.57 − 1 that elop ab the ww in of y from km or , with 6.3 = ears, of and o the ligh the c y computed tidal v is e. HST s determination. mag. 0.07, 19.1 e star region mag. − of to that (1978), that v Ko 1 system line t the only A brigh three ∞ . are correction star curv b forces, (A), enigsb second data. A (MPG e With m The their only observ is profiles star is V tness constan e v stars A A, with v constrained are ( strongly sy m ∞ solution erger = primary A The and stem (B) v consideration log a star 1989), deriv ed 0.41, ( undergo − B ratios, M (A, distance arising ˙ ( a t ) 6.5, = ) this, L predicted A ν line et o ation B = , A 0.26, v = B, 1700, distorted of = / er M the LBV V al. ca had L ˙ to 13.08, to B and B 11.7 and es profiles

BP90. v the 0.1 from o, mo relies v eat ) and absolute (1998b), = 2600 c elo / hanges an = = con w WR C, is dulus − using time- mag, mag, cities with ould 0.33 and due 6.0, 6.5, the ex- the tri- km re- 50, on In of SYSTEM Fig. HD (triangle) stars. with Meynet HD 5980 24. then, is asso M This kno spheric BC 6.0 sumed if minosit et (2002), mo ev p stan ho luminosit sual classification to NGC erio er,

BC w bol O4I, 5980 al. et del V wn (O4I), ev = t P ciated A on and d al. magnitudes. luminosit ossible follo 346 = 1994). er, that = o − to calculations. = y for or v whic absorption the (1994); yielding , 4.21 er − 4.79 y star b are wing log − Drissen using 5 predicted e whic is with HR the 6.5 the h mag, lo O4, ( If, noted. mag consisten (BC mag. C L implies cation y some MPG, A diagram: h mag luminosit the (square). ho recen based is star / log ∼ leading UV L if w lines et far

solar ( Ev ev of − The Near O4V, of H-free L ) It as t a a B. data al. 5 t er, C the olutionary on ∼ eac larger b “mo y with / b will mag) obtained olometric star ears. L y y If b largest to star 7, the h deriv ages Other or olometric

eruption Ko are derate” has WNE it of ) log b based an A BC analysis than e enigsb = B are and the is ed ( a (crosses), L assumed, assumed stars remained Star v trac is uncertain 6.1 a = B ailable. indicated from three star correction a / corresp not on that assumption WNE − erger L ks magnitude maxim larger (O4V) asso

3.93 of C differen are (Langer a ) stars the photo- of = star is WNE WNE ciated et ho t onds star, This from con- mag with um, y an 6.3. 131 as- lu- vi- w- al. or of in is B y t © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México ZAMS age classified et ZAMS in resp minous trac w using cluster cluster sym oretical high trac Sk WNL 132 as 5. 6. al. 80 the Some Figure ks ks b ond sligh classified The The star star, adopted. fa T b example, of log adopted trum. sp sp adopting F sp in based (O4I). NL is WNE, corresp b T (log implies mass-loss ols) y or e A eff (O7If (2000) phases. v data from ectral ectrum ectrum (in are mass § mass and 1978, ored. ( TE sky for star, tak mass HR L ( tly to = = 3.3, L star of are it B, B relativ its 24 . also B millions en 42,000 effectiv / ) onding lo on star the it and as Meynet tak 21,000 / Once larger analysis diagram L somewhat T and b is a distribution, illustrates found indicated. w L luminosit consisten as the of Its Assuming

is eff to et from The R obtained C, if ON3I is plotted

the rates en H-abundance most ) similarities metallicit A w e O3V((f HD lo ) assuming it B. its corresp dominated lo = = een WNE = T cated K. e = helium from ages than second again, cation to eff w of nitrogen et K I p 5.82) 6.3) Ko 56,000 Assuming 5980 during luminous I(f ere constructed 21 osition 60 of temp t in al. a y y = lo ∗ for the ∗ enigsb on ears at t with relativ ond )) 3 ). MPG89 BC R this and w yp w and constan y O7 the (1994). 46,500 , most is this ould but er million on

a to b as the 31 upp It erature e 23 Z y with , the K. few Y/X on enhancemen and b to diagram of than V, is, adopting 85 a X is erger MPG89, then ab Dec. y = the h optical stars ely abundance giv er No ydrogen luminous WNE b largest the it that But an the main the o for M t ∼ lo BC 0.001, e v p These mark (their with (O4V) en a v ∼ close y cations that HRD e

ortion is luminosit m em ears. T 1994. O7V 0 HRD of the fourth , et erupting the A B1.5Ia 0.63, uc of = if the of (filled and a is sequence b classification. the ed R emission-line but ev h = of er and to it star mo − time uncertain al. B WNE T abundance ten ts, suggests luminosit olutionary star star, of suggests discussion lo MPG or Since 3.77, Sk able with along NGC 53,000 star a ratio HD from = is W 1994, dels most w + the circles), tativ and y curren assume K (1996), A. er alb 42,400 80. 15 , b not of OENIGSBER star’s sp eing, 5980 then XI). the- star cor- star this and and and (for 346 can 355 F orn R the the the ely ec- re- lu- A, or t K is

y y a a a t that ligh H-p to of binary nally to along star. star v star from accreting quence ha HD tle is b third, pro sioned W Rotational v star stellar w cording left are mass accreted star the stars The to non-rotating is accretion to w h H-ric is alue, ectiv ydrogen een as ould ejecting ok GER o in v not a 1994 the explain is osley duces HD The e t sev H-abundance o the 5980 rapidly a B first C w the that h or A increased kno place. remo curv a The b b and e the as but the b easy less eral y 7. HD in mo la een with pair, M with 5980 core, main phases WN e with Decem to y range as wn lo 2000). resp a SUMMAR p whic Z system v e) pro O-t ev higher ers. is dels t abundance, part v lo lo v the ossibilit cations ery AM w the p more massiv large 5980 ed. mixing m to ery olutionary cation rotating this ossibilities cation ab In o and in accreting a star, trac is cess yp onsible leading sequence uc crosses; h S Indeed, lo ev b H-p reconcile (T 2.88–3.06 of out significan LBV square. whic The a and order e h non-standard er star Th cations = olutionary massiv system. ks t amoun luminosities alon 1978. are the m star. obtained yp (see e as it y o (declining the 120 on us, brings ultiple of ma of star or), h Y second e the is 50% B eruptions for m ev accreted indicated to to an star of et review AND one the y star ust whic material exp the that trac prior the olutionary is to M e t Assuming Both and noted a the tly o the that H-ric understand scenario, million al. LBV-lik than v not of

(Maeder Hence explain fresh more ected system erestimate HRD of b k luminosit A from h p during B trac the and three e eruption H-ric 1997; CONCLUSIONS WNE to whic of ossibilit p the implies a b is h has gas than star the scenario ortion for with star y in a in b WNE k progenitor H-fuel from la massiv not observ c that y w ecoming Gallagher v M it e h haracteristics scenarios h it mixed ears. y this Fig. star olv mo ev most con ould although Heger, that mem A the eruption ers & c at Z A. the gas m is haracteristics y a olv y AM consisten the es del. and of that ust the its taining and Meynet star but the on, of con is T ations. triangle; A 24 p e ha ma in ed Ho imply b when non-rotating the suc star S ev ak ost-main with core, star curren that to ers mec mass corresp v ha a in tradiction. The its as = Langer, same y an olv w en star it e according A put h of 1989). WNE. eruption ev v the b v order recen 120 not B follo ev curren e hanism ed its O-t a ery A e at of a (whic t star star star er, 2001). a There whic use of origi- olv t B of forth is mass en close with time ma con- zero o face star M ond and yp age ws: the the y wn ac- lit- tly se- vi- an an ed lie to et of of & A A It A B

h h y e t © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México determined the should v a of raised approac it imation sen ww collision limited fied, able. the sho reflect wind-wind all serv wind star. eac the dep primarily v tion 1995, sisten 3100 bital is and profile termine order required wind primarily to line of v particular, stars understanding p determine ∞ ery elo onen y determination an ionization, the wind-wind (A) h ted c ep c Using One enden that observ ed ww cit secondary profiles wind-wind k comp since fast mo of phase-dep collision in t o km eclipses, ts, to eclipsing cone and Ha F y stellar c b that regarding line c narro v v with ∼ urthermore, h hs the n of del oth the olv ariabilit leads curv for estimate sho it region, it ving um t and using onen s ations asso the the to the 1700–2200 the − follo collision v 1999/2001. is ed, the w is profiles t has strongly used or plausible ariations 1 c b understanding the w w an es. alls. k necessary masses the er consisten collisions. geometry dense ma WR-lik not o to ciated established from ts ev parameters comp do and with wing estimated enden collisions of cone system, v a mo stars. y origin uncertain the of of and ariabilit olutionary for the wn . jor here, direct The HD effects Hence, the their a del this the UV region. ma F stellar onen estimating data an questions profiles four 1989. is WNE these suggest t the through conclusion ortunately with e c are km degree 5980 v haracteristics v calculations A y t emission in although mass-loss folded to can ariabilit under ariabilit impact observ additional sp The allo Hence, with y pla t, fact con pro preliminary difficult the for t lines obtained the establish ectral s these y ranges, the observ that wind, star − The HD According star y only status wing concerns tain as duced in 1 that ranges that to a HD emission the its the gas around ations that and stellar role on the a of the y , 5980 y one analysis B, lines whic ha as that limits, b p effect c ed con rates. whole the of with the WNE thin can 5980 e haracteristics. star to ep ortions the evidence flo as of v wind has con and to the in in originally b done during v e P of o in tributions of in wing y h has ∞ follo its could w that terpretation the binary analysis c use pro fit determination th the Cygni winds star sho b tribution the to a B h- lines (B) ell wind recen on the ph nature the and the e these are ho h us LBV of stellar v high b the through p w yp ducing and the wind-wind elo ysical c attributed as of of een w the first ossesses nature along are k the B winds, arise 1989/91, ∼ far with emission not p othesis. ev are m tly summa- appro cities eclipses absorp- pro the of profiles the / ossibil- system during phase- simple degree ust v er, classi- WR to radial 2600– yields of wind- a steps alues com- from b b eac v con- vide pre- and in line due een een the the the ob- ail- de- or- an an b In x- in of of of h a a SYSTEM e of understanding questions no age binary predict Huc orbits and ( orbital tion sion not lo dard itor tions observ further theoretical rized firmly siv It the of mass binary tionary 1. 2. 3. 4. = wing v is the e its HD a. The h mass is ww WNE) binary b of of What What Giv What sions? files roneous wind v the the Sbaffi duced anisms cen ing v that also t curv ev ariabilit transfer olv in e three Ho or ed. ∼ N establish 2001 are the pair phases 5980 the systems c’s abundance olutionary a tly fully status en study constrain T e 1993-1994 in in abundance w 3 due imp the m determination es able that structure a some is ev radial Th et is is Myr. the mo the system A+B uc adv detected is is is Is resp star for v of comp quan er, mass binary ortan the ariation the y established. al. us h most to w and and/or dels the of of the emission anced 5, of eruption? are timescales ell smaller a whether of with observ the onsible I 2003)? wind v HD According stars quan B? effect tified, ts pair this onen the sample elo the ep conclude effect determinations? t on scenarios, ( ma determinations lik relev origin eruptions M that of standard to pair are o p cit stages Is strong ely lo the in ev y c Z questions titativ particular olarization 5980 ts ed could the eclipses A hs) k AM of y H-abundance cation the lines. b an olution for necessary eep it deriv the star large can is the indicates and e curv of Is w in p t and as stars? of S in In LBV+WNE, asso a eriastron v raises the of ≥ that it not suc to in e mass-loss y alues stellar ha result b B w 1999 and ed in es B a ev Th the effect e addition, binary-related? ev enough 120 to on ell the and mind the v h is ciated p instabilit with that olutionary placed relies due e only HD olution from us, system, osition the systems). . b Do as truly v a the that of b M rapid ecoming of ariations c that ten of apparen een wind-wind winds, haracteristics large a on un to es the the

5380, that passage rapid star H than for ev determination completely the H-R tativ ), to rate? til with on wind the a the the olution a (at (see the masses to presen in under y then WNE but gaining line-profile lead the n the v A+star the R that curren um e scenarios what ery answ effect eccen rotation. Diagram tly line order system’s differen V a The progen- eclipses (Villar- v the conclu- distor- also on an sup star ev b mec v to t-da stan- colli- mas- aria- er star, with aris- can- pro- pro- er: olu- tric 133 fol- der the are tly er- er- re- in- on an h- to of of of B B y t © Copyright 2004: Instituto de Astronomía, Universidad Nacional Autónoma de México 134 Breysac Barb´ L. to Breysac pro K. Bateson, Barb´ transfer ing Bateson, fruitful Breysac HD Figure Auer, 26555. Barb´ UNAM/DGAP for t´ Barb´ Azzopardi, op the in sion computing w an, as 5. v erated Smith J. estigation drec Nota ApJ, Conf. 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