© 2007: Instituto de Astronomía, UNAM - Circumstellar Media and Late Stages of Massive Ed. G. García-Segura & E. Ramirez-Ruiz 6 (rob b R v could aparen w not Las but estrellas rarer nous and v ena, of range the the impulsadas their la are y pap represen and or The p En Da from activit Key h THE ersit ariabilit yp e er evMexAA armer v VY 1 ariabilidad, vidson near them p The A este Astronom distinguished [email protected]). er, ergian HR existence luminosit kno hip Wor the extensiv the co ost-red y sometimes high late ob 1. few represen y b te CMa, ol I . of ergigan CIR e diagram wn. art the temp jects, t evidence ev ds: WHA in y describ en h also rango either t’ , a 1994). A highly yp mass olutionary termediate–t ´ V ıculo Minnesota, CIR and y p v empirical (Serie for ariables, sup este e They to ergian ery eratures. or y CUMSTELLAR y of T all Departmen circumstellar ted sho tes y en violen la the M. ergian loss actividad IMPLICA e de CUMSTELLAR corto, the (Figure IS ev some en short-liv unstable, b related r In v for w the ´ b egimen evidencia fr y elop olving are de ts The A temp y ´ algunos ıas rates, upp their this photometric high the the are t, state COOL t upp Confer complex Minneap describ all ha e de yp whic son (RSG) t, er co 1). with eratura pap the b v that sp co ed high Jager to e er p con mass y e v son ol 116 b v ost ectral ariabilit of ol las or . These h oundary high casos ery large ev luminosit encias) de er, most co h HYPER v TIONS o sp olis, ma h lie most yp mass ectiv olutionary Ch inestables, “y oler stars main yp estrellas circumstellar la loss (1998) episo ectral I massiv ergian represen y urc just ello mass t use ergian complejidad and los MA luminous include yp b a y MN h temp loss , episo of e ENVIR , w” in sequence dios es a (Humphreys 30 GIANT? and grandes resp b y the St. TTER t has these sp ts e loss gran elo yp transition A b , ts, rates. m´ h F 55455, stars eratures des ectroscopic oundary tado 6–11 v yp stage, w es onsible term in de to as the como OR suggested Rob ery and SE., phenom- excesses, kno ergian this escala. ranging some M. stars in luminosas ejecta alta — Lumi- excesos ONMENTS Man lie del p (2007) stars, lik erta ‘co wn their ev or THE USA Most Uni- and lo ABSTRA up- ST ely for RESUMEN on en or to material in cases ts p ol & is y los stars p erdida M. ARS: of onen recen of infrarro tip t Humphreys w MASS cono large in these o os t shot top p their history that ture bluew ejecta m loss lar the temp p 4e eral ρ high namical (G8 and (F HR and ev CT MASS de the de ey remark eculiar er history ulti-w Cas olv cidas esp ectado Ia), IR and or T jos manifiesto M-t masa stars diagram, of HR VY the upp episo of Ia). h o OF ed mass erature of infrared most ectrales ard equatorial yp excesses will the b (F8p . the as LOSS NML yp a LOSS able G–t differen en etter mass er CMa 1 stars diagram, ergian v ´ instabilit sp ı apparen These in des The elength ev de en e THE b como most HR HR loss ectroscopic la if h yp e this olution Ia), range dos yp h and sus Cyg a understand that loss emission, (M4–M5 parte not de yp e) near presence — Diagram ts Diagram. sus and episo record t ergian MECHANISM luminous stars regime el ergian ejecta, hip HR tly h steps la are historias pro mec y images ST COOL (M6 w yp all he , (6000–9000 material altas circumstellar the e these sup A ergigan des driv a ARS: ergian vide p called 8752 ts, hanisms ha of of w ost-RSGs. a ts semi-forbidden Ia) v I), in strong erior are ere or and in upp o ariations v their en µ tasas la the ccur. the e with IR kno clues v their and VX the lac Cep (G0-5 recien ts, ery tes unstable obtained SUPER b M. selected the HYPER er C+10420 circunestelar other y del ev wn in k curren molecular apparen that IR the Sgr large-scale HST/WFPC2 K) notables, de luminosit massiv termediate (M2e La to olution of “yel ev diagrama tes, C+10420 ev ejecta. Ia) to In olution with structures their fossil p in (M4e ma olv dominate ´ erdida low GIANTS t termediate-t as on giv their high Ia), aparen and and e y ed and t region GIANTS: increased or of evidenced stars e void” ev temp shells, the y In emission, IR Ia–M9.5 ´ co ıa S expulsado. us these con prior olutionary across HR resolution p b VY C+10420 de HR (A–F temp this P ol ost-RSG oundary de temen basis er a in erature , the en v of stars in where masa, ectiv 5171a snap- bip CMa estas (M3- en mass ter their co brief sev- era- yp up- dy- the the Ia) b ol, I), or te o- of el y – a e e © 2007: Instituto de Astronomía, UNAM - Circumstellar Media and Late Stages of Massive Stellar Evolution Ed. G. García-Segura & E. Ramirez-Ruiz ionized the small( Humphreys, b detections 5 ris ρ appro has emitting Fig. with of tance Morris from solid the plications P NML NML cumstellar b (OH/IR y oundary er, Cas, × 6 & There Our The In its latter m . 1. a 10 4 b line, a ximately the uc Cyg’s ∼ oth Jura places Cyg, × v this HR 5 A en p & ery h results h p eculiar 2. 0 10 L ydrogen vironmen sc sources) Cygn o and 00 . more large t OH/IR Jura w

for for are 8752, 3), hematic of w nebulae. − NML 1983). short ob IR erful (OH/IR o 5 & it ( circumstellar the M vious the red asymmetric C+10420 ob us M remark are 1.7 Marengo near distan asymmetric 1983; asso bol HR

jects. co CYG OH/IR X (H pap sources, ENVIR ha t y episo sup quic HR kp HST/WFPC2 ol r ∼ ciation sup and but 5171a the v − source) I c h er, t able e ergian I) 1 Kn¨ Diagram yp kly − – ( dic from erbubble extensiv (Hyland ∼ and con empirical 2006) 9 small IR SHAPED ergian source odlseder I ONMENT . summarized: w en 5) 30 and similarities material mass C+10420 describ tours Cyg shap ts ere v ejecta 00 the VY and elop ts with from µ sho circumstellar for marginally e NML e are Cep; OB2 loss (Humphreys et CMa around e images and w (Figure the e 2003). upp a BY has that al. a asso the iden that our mass and and mec most Cyg VX luminosit er in complex b ITS b and w ) tified ciated 1972; et een w results luminosit e NML hanism NML the (Sc ∼ Sgr VY w e 2). COOL This (M6 loss found resolv luminous een the see shap h 100 with 21 X-ra uster, and 1978; CMa Mor- with y Cyg Cyg I) rate and dis- cir- im- the ed. cm for no p ed in of HYPER is S y y crosses. c stars. et and seen analogous molecular action ionizing masers, (PDR). p that observ tion cally the ence, in eled and shap to region drogen w photo- (1983) closer uum Morris nearb GIANTS The osed as teresting al. the Our Figure wind the coinciden empirical of e. somewhat the it in symmetric, y they (2006) to ed b on reflection w do the sho asso the The surrounding & et near-UV T photons as suggesting shap images NML es b o w the is Jura to w 2 photo-disso y w suggested WFPC2 een that the test ciation not ed dust ater sho photo-disso an Habing prop e t upp HST/WFPC2 from Cyg of with the that result of 1983). ws “in shield our nebula, y the sho expanding from masers (from con er the ose an co v molecular Cyg the than luminosit w erse that the images h an the the asymmetric co et that yp photo-disso that of enigma. ciation the plane circumstellar on disso uum Cyg M The OB2 othesis, w ciated al. Photo-Disso but is luminous, the the asymmetric w ater atomic engulfing sup the the not e wind is ciation OB2) flux (1982). y surrounding presence also in parallel image. outflo are (see ergian the b b masers, molecular shap teraction only closer oundaries. oundary T Sc from from ciation o one-sided matc lik h Figures result farther h w ydrogen e explain hot surface uster similar ely t NML ciation of from material Morris Lyman It “in lik to of Cyg NML hes as the is imaging is stars e of v of b ionized the material w H et erse” 1 sho oundary NML out. its NML Cyg esp OB2, ell the in a sup distribu- en from I Sc its and Cyg Region” al I & wn con star spheri- con as v ecially exten in h region in m erim- elop mo uster m pres- Jura H Cyg Cyg 2 SiO and as ter- tin- i.e., uc v the the the h ust ex . so d- y- in in I h 7 a e t I © 2007: Instituto de Astronomía, UNAM - Circumstellar Media and Late Stages of Massive Stellar Evolution Ed. G. García-Segura & E. Ramirez-Ruiz firm p ing diate sp the minosit image rounding few Sc stars Fig. 8 Humphreys b it stages sisten en minosit yr extraordinary stage, photo-disso If b et terial y ositions e y 3. h − v ectroscop , the al. uster its elop Jones IR the 1 red high there kno 2. IR (Knapp in a t temp C together 1998), SE but outflo in of C+10420 with y y The e. consequence wn sup large the +10420 et teraction of the luminosit b of massiv et of is oundary eratures, its al. ciation. ergian y stars small the HR w our L et , more the al. then optically & ∼ (2006) en distance with mass from al. 5 H Morris diagram e v mo ma star × (1993) – that t 2 elop b it with star O maser y 10 ean-shap A region. the 1997), del . y Ev in b app NML loss fit of 6 masers POST–RED et e is b With define obscured en disso the L ev e for 1985; to w has and high of ears preferen com

een one for rate olution. emission without , the IR Cyg NML ed HR 4-6 (Jones and ciation most its pro are bined understanding the that C+10420 the mass Oudmaijer of en asymmetric of diagram star ximit high kp v is p the sup tially empirical Cyg’s elop main 3 olarimetry lik the assuming c surface bip With SUPER et to m loss erimp - ely NML most e and ulti-w y mass 6 olar al. the molecular of shielded sequence to is circumstellar × b in at its the et osed een mo nebula one its ESE, 1993) Cyg imp Cyg. GIANT (Ric 10 a upp loss the al. v in the high bip deled nebula. − elength to shap terme- result- ortan on of 4 hards er 1996; OB2. RSG from olar- rate, HUMPHREYS final con- con- ma- M and and The sur- the the lu- lu- ed b

y t of gian ing that Oudmaijer only men Moreo obtained plus tral tures region ing a circular a 1978; (LBV), 1997) they or with HR mass large p to Fig. the ergian uniform red IR knots, the With A complex it the ts ts 3. t diagram, one one it C a yp concluded stars. are Jones our sup rev infrared v of few suc in has v er, t A +10420 past e a proto-planetary/p arcs ariet the or with ealed all ev HST/STIS this ergian b from h W ra short the outflo its est c olving other more inner et et HST/WFPC2 as y-lik olf-Ra hanged evidence or double-p few y photometric ob bac HR al. candidate of ρ al. in a lo late excess exp t w and e that vious complex Cas h ejecta ops p distan structures kground 1993) an y undred features, in bac of diagram, ossibly osure et 1996; significan F termediate-temp its within gas spatially for and eak IR ev k star, circumstellar to and within t and olutionary C to reflection high HST/WFPC2 ed for reflection in mid circumstellar HR Oudmaijer y w ost-A to images Humphreys +10420 history ears. or H ard a and apparen 2 strong including a but an 00 tly α mass 2 nearly a 8752 star A resolv 00 of emission GB pre-sup the of S sev in (Jones IR the (Humphreys nebula. (Gottleib Dor-t the in shells. loss is C the o phase eral maser nebulosit t blue ed stage spherical ccup erature star transition c 1998) a +10420 em condensations hange image en et episo past erno sp yp p small, et profile b y ost-red vironmen side (Figure ectroscop al. These edded analogous e for Measure- al. emission, the v des cen indicate v & in a sho y ariable h (2002) , of distri- is state. Liller semi- lo yp 1993; sp mak- et same sho tury from wing dur- star. fea- w the the su- ec- er- 3), al. er w t, y . © 2007: Instituto de Astronomía, UNAM - Circumstellar Media and Late Stages of Massive Stellar Evolution Ed. G. García-Segura & E. Ramirez-Ruiz in the the metry The CMa pro nebulous the tiple (Danc bution, activit tions, the (Humphreys ferred imp CMa knots case observ and gested at bined cumstellar episo et torial and absorption on Its of v placed most ing frared en clumps losit ties emission reflected km “kinematically 4. el t groundbased al. its 1.5 v digious Multi-w T The the VY 1997), the arcs south ortan across upp wind s y in origin not ery apparen o − des . ev and luminous is (Smith near hi with temp disk (2005) y ed 1 not temp or learn source kp the across It that en Kec of NW er CANIS ejecting con visible on ma with to extreme near t et w v absorption c line its arc w asymmetric m brigh ariations luminosit stars of among necessarily est, ejecta. VY en the the or its rate, erature as a in (Herbig y k trary the lines ust erature al. more v arc, they equator. t vironmen terior & VY b obtained elength to sev bip 1 and resp rev et high the apparen star, e random NW plus distinct” CMa’s asymmetric ev star’s t b Da MAJORIS telescop for data, expanding and the large eral in al. ealed olar e knots. the 1994), CMa’s to olv end red ab ect w W OH the vidson optically mass and understanding ev in SUPER relativ all the ere are y arc 1972; e previous ed out north lines is structures t 2001) olution ill-defined outflo w t b to Therefore, mass HST/WFPC2 apparen tly found amoun of t aligned sup luminosit of maser w long-slit co consequen a oundary orien o stars with due pro dominated whic nebula. e The o loss complex from the mak massiv the ol whic complex outer ejected 1994; w to ely and ergian brigh Lada lo – duced w. GIANT est, nebula, loss rev h to tations h morphology thic rate a Doppler es its ts ops kno AN map em yp on VY brigh h mo the t is with strong W extremely ealed c t filamen are in sp of e sp ergian y whic de hanges b VY episo t surface. high k; & in short wn. The e dels expanding caused tly w of filamen EXTREME ejecta, edded star ≈ surrounding CMa ectral ectra is the b the gas pattern and the demonstrate e t b Jager consequen the Reid evidence y 4 10 of an 400-500 y clumps h one sp ≈ CMa × a des A mass images motions four v lo with ts nebula 00 the ev high and timescales. is tary 10 eculated elo emission the t HR 4.3 complex p is axis calized with in across, , t olution. star, tary b Humphreys of its 1978; o that yp also − (Figure 1998). kinematics strong y cit prominen one w 4 the slits of dust COOL a mass arcs loss our × an Diagram lo e erful M arcs distance of at y for of yrs HIRES 10 and includ- tly arcs calized sp of v visible

and RED of gradi- define of nebu- dust wind, equa- elo ∼ Mar- most com- sym- 5 y rate, w m ejec- ecial that that sug- at L and and loss r K ago VY VY cir- the the the ere 4). in- ul- in- ci- − 50

to HYPER is y a 1 t I . sational ev separate while app arcs regular gions 2003). recen serv the at Fig. and to with second differen transv presumed at radial sho motions kinematics GIANTS 5. en differen THE differen the w W The m ears ed ts kinematics 4. and a tly ultiple e that on the erse history motions for star, (Humphreys in t ep . The and origin MASS to and instabilit the angles ev knots o t t axis the t the w the motions c en b of v arcs h HST/WFPC2 long-p o times star. confirming e elo directions ts OF HST/WFPC2 outer of ma arcs h the of the of closer LOSS cities, of yp relativ pro and p mass symmetry jorit y STELLAR ossibly the W ergian erio the and . ejecta cause vide and whic filamen et e knots Indeed, y conclude to MECHANISM mass d ejections e in arcs al. from of of clumps to v h their t a the differen ariables up of including image in 2007) normal the star when the complete . tary and loss the its to ph star images A pulsational origin outflo CTIVITY plane that ysically circumstellar not ρ of knots 800 arcs of ha t small and com w is Cas RSG’s directions, knots v VY ere aligned e ws. most the the yrs to bined from w of picture v – since are ere ariabilit shell (Lob CMa ejected THE measure separate the morphology ago. Our total are and instabilit lik consisten ejected eruptions obtained with with el sky ejecta. ejection ely sho mo R and results of the Small et y space OLE more wing ving pul- and an the the ob- the re- al. ir- at in y y 9 t © 2007: Instituto de Astronomía, UNAM - Circumstellar Media and Late Stages of Massive Stellar Evolution Ed. G. García-Segura & E. Ramirez-Ruiz 10 VY knots, ple, and en tributed netic/con lar able observ tors). H (Barv Ori VY confirm its (Szymczak ev estimated activit w more r etry mass yrs. of those 1 cumstellar (2001) the loss although 10% red 3000 within do ermost amen seemingly lik rate. cally similar ≥ yrs asso − ould 2 M en t 2 e 10 es O brigh activit ejecta. In Measuremen In (Smith total CMa sup

regions (see ciated episo dep ts structures asymmetric CMa In starsp − apparen of of (Vlemmings ts thic loss not ainis y results, than 3 with y ed the b con v ears 2 M and a estimated ergian its massiv the reflecton t endence e and ery the 00 and n similar k to mass des v and

rate on y tak asso the knots umerous these trast, random “y ectiv , to and ots optical et nebula. with The et nebula a 10 yr & that lik total filamen on existence ago, either knots ello tly e the mass within mass al. al. the b t. Humphreys 4 − morphology ciated of and ely e Cohen G in in e 1 e the IR indicate results ts features w” ma , the 3 fashion, The flo is to b of 1987; 2001), at regions less mass the Zeeman the at probably sev mass arcs y C+10420 × o et the and of accompan ejections. large to loss directions, non-radial ws visible pap y ccurred ts With star. a accoun h least the 10 lo NW the eral with al. yp the n prominen b luminous, b n solar-t of 1997; in calized total umerous not − e Kem at loss ers umerous rate e infrared also in ergian the last 4 “starsp 2002, a lo star’s 1.5 and represen the 0.2 times M a the circular arc ∼ spliting This large et ≈ magnetic throughout the calized b t is visible dynamical after short-term ev ball when ∼ y imply mass yp 600 3 are al. the mass × ying Masheder to 5 and ev not Using yr circumstellar en t Dupree analogous pulastions pro 10 00 2004) × ejecta. t e surface the activit 10 en ots”. starsp IR − 0.4 arcs, images, ts (2007) & less 10 arcs yrs. − w evidence n magnetic the arc-lik 1 t iden cesses outflo ts p of − similar umerous 3 C+10420 in of the ere ejection through − magnetic o at sev M a olarization 2 v M 3 surface the v field analogous M the massiv and er star and M shedding VY

erage Large knots, y differen ots, tical. eral and

time ejected

This the star mass assuming estimate

e the ws et with OH could yr Smith NW to from . or SiO throughout or the features, had CMa’s structures, con high for − collab al. ha nebula field Based past ev mass scale e VY the small and ejecta w 1 emission estimate photom- more, the loss 1997) Lo to and fields . v a arc t RSG clumps en as v masers ceased e b m differ- These of ab ab ectiv to 1999) times cated mean et mag- CMa mass e ts opti- b 1000 v HUMPHREYS that ulti- that out- rate ora- still of w loss ari- jet- cir- out een out the the so- at- fil- al. on as or in in of of ∼ is α 3 e p cen tit similar during are 1954j, “caugh tury nifican Car sup b or ha of catc 1994; the “sup tions high times group meeting. v RSG the though Strong p fields. NML strongest red fields b to en & p loss yrs ev h ectiv yp ostors” een er een ergian olv tly v Bo this b “ ter et Another η A I W The e erno normal sup ergian ago sub hier e , η dynamical p on analogs” erno w ed Car w and SN stage. e b rep called small a driv erio e/magnetic of al. Cyg), call Humphreys, tly Carinae” and of as ers t een small (Figer 6. ergian ts ject ob co no whic magnetic v (Bl¨ I’m the case massiv sev name. in ae orted is v 1961v the is So somewhat d b 2006). among en oler ts) w THE a ject. (IR 1992) and them ecause V1 b oc LBVs, v the subset the eral ma imp of surv h reason sure ecause This sup program ariously observ I the b group k t for for LBV’s C+10420, y though et (V RSG, er this in their y ev e in b the act” SUPERNO ostors” in instabilit erno thousand large-scale eys an est “sup v at ha high olution al. episo the con et The NGC stars they activit should ariables fields sev the ha of reac NGC e meeting. v to sev include Da ab al. Dyk kno star v although e among surprised v total v (Drissen the that RSG’s, eral increasing 1998; t erno ae called ection e “pistol” call out dic mass sp recen OH vidson, hed eral I’d will ( 2363 2001). and wn b η y of 1058, ecifically S at are VY y een not 2005) surviv mem v ma mass are these just G, 7000 Car, Dor (Humphreys luminosities a candidates, maser V example. the during of con Na P tly b v are loss the uncertain. whic “gian A but and arious imp e y disco b similar CMa, Cygni the et increasingly b IR that jarro V12 briefly e & also star v v discussed IMPOSTORS ended, es. order ers exp ob A loss. LBVs, stars ariable ection evidence T to episo it ostors”, C+10420’s al. h turbulence U Smith timescales yp regions t v viously ab o these of app has ered o erience in near there implying times, eruption” VX 2005) ccur e surprising Giv in 1997, out Other to “sup In this men des of NGC I ab ears most and recen the or In’s. and Its increase VY in en & the 1999) the Sgr, 1 gian out in during a w LBV’s, group among tion relev are LBVs erno (Nedoluha the high ma kno 2001; w eruptions mG as Da 17th magnetic that mem som the the 2403(SN CMa. the of tly co e for galactic surface. ma t Sev 60 surface y appar- vidson S no v recen a an wn ol whic some- LBVs or erup- giv a p what mass b ha ha y b p v sub- con- that b cen- P co - ost- this eral t sig- im- een P h pa- the ery e ost ers er, al- “ b en 90 v v as to y- ol e- h η a e e e t © 2007: Instituto de Astronomía, UNAM - Circumstellar Media and Late Stages of Massive Stellar Evolution Ed. G. García-Segura & E. 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