IUE Observations of Circumstellar Emission from the Late Type Variable R Aquarii (M7 + Pec) A

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1980 IUE Observations of Circumstellar Emission from the Late Type Variable R Aquarii (M7 + pec) A. G. Michalitsianos NASA, Goddard Space Flight Center

Menas Kafatos Chapman University, [email protected]

R. W. Hobbs University of Durham

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Recommended Citation Michalitsianos, A.G., Kafatos, M., Hobbs, R.W. (1980) IUE Observations of Circumstellar Emission from the Late Type Variable R Aquarii (M7 + pec), Astrophysical Journal, 237: 506-512. doi: 10.1086/157895

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Comments This article was originally published in Astrophysical Journal, volume 237, in 1980. DOI: 10.1086/157895

This article is available at Chapman University Digital Commons: http://digitalcommons.chapman.edu/scs_articles/82 1980ApJ...237..506M intense THE type Aquarii this the tions stellar sion International spectral (1950) 3729 (2321 (1548, 3200 continuum accompanied of rather with © [0 1909 1980. Additionally, Ultraviolet which n] © AsTROPHYSICAL conclusions star. continuum A) A), A lines lines made and The A) American and companion than 1550 emission show and type the probably 3200 deduce emission are emission-line The Subject system study and observed range are (M7 American and appears Low-dispersion [0 IUE of Ilovaisky of by most A), Sun, identified also H Si the giant. 111] UV A by strong Ultraviolet Mg [0 + observations its [0 observed. II Merrill observations 1 of that headings: Astronomical the a are drawn mass-loss pee) Si forbidden mainly detected III] lines from two-photon circumstellar suggest independent since general JoURNAL, continuum arises II] in II I. likely which coexists Astronomical We Laboratory Laboratory III] IUE discussed bright (2796, the (5949, INTRODUCTION permitted and the (2470 spectrum have and that the identify (1921, such (1883, from strong from to optical Explorer OBSERVATIONS Spinrad THE originate R the UV in spectra We Society. stars: stars: rate hot 237:506-512, emission continuum. with 2803 emission-line A) 5007 are the Aqr of been hydrogen of a presence continuum, earlier for for in observed emission. attribute 1935, of companion. a 1892 star emission. of the emission emission-line the LATE R UV and All superposed and long-period binaries- Received A). a the dense A) spectrum is Astronomy Astronomy between wavelength (1966). the Aquarii Department obtained rights relatively (IUE) secondary the can and from late Society A), lines and context 1950) Forbidden yet probably optical primary of reserved. recombination TYPE 1980 primary compact This are is the produce 1979 Accordingly, c lines be type [0 Strong the spectrum a and 1200 a and (M7 attributed that by The III] consistent warm and and April15 stars: sufficiently origin n] on with variables cool confirms A. of intensity compact observa September OF over spectrum of Printed as the • of Merrill VARIABLE star star. A (3726, (1907, reveal Solar Solar general [0 Physics, + a our G. emis a star. a Provided permitted, nebula enough C and CIRCUMSTELLAR ABSTRACT R. late UV chromosphere hot M.KAFATOS white dwarf, circumstellar the the pee) bright III] in MICHALITSIANOS of IV R is model W.HOBBS Physics, U.S.A. Physics, Low-excitation to AND 506 10; that have George spectral faint the Balmer ionizing ultraviolet accepted flux density, in 43.12203 tinuum nebula emission emission as close tions with most match radio nebula red whose Seaquist should sequence source for 1979). 1979), involves semiforbidden, R by NASA NASA been size The This to has § Mason the source AQUARII comparable measurements shells- properties II, the is escape proximity (T likely source an of recombination of that 1979 orbit obtained properties and the photons star circumstellar of been be stellar Goddard Goddard and observed where ~ 1974), excitation and which lines. properties, NASA Astrophysics star C continuum. University electron emission at distinct limited present of October 10,000 III], or more about originates size detection EMISSION at 10 86.24327 suggested is stars: a system bright of Of we 8.085 and (M7 star. the C to I-'m to to is Space and in Space of R of IV, recently in K) the lack the 18 extent comparable or particular low in excite is lines if temperature source have the (Schmitz individual at Aqr being forbidden We +pee) nebula, a the MHz, Si somewhat our strong in white Flight and Flight an From primary exhibits binary subluminous, GHz by 14.9 from of dispersion ionizing III], by the find of between UV estimated the FROM 0- a (~ direct data of identified not as stellar GHz Center Merrill Center Fe 2.695 (Engels dwarf [0 1-o primary permitted 10 our et the a the excitation interest or continuum system. spectrum an 0 M7 15 a II, II], emission to to al. low-excitation brighter does nebula observation. Au B-type (Bowers continuum observed companion, T multitude analysis em) 1200 Data MHz Mg UV in SiO the 1978), and blackbody ofT* star ~ (1950). 1979; central the order also M7 in not continuum II, and 15,000 binary A and [0 maser from is in (Gregory are System than dwarf our lines temperature, as 0 and and ~ late as comparable and Zuckerman III] the we adequately to located planetary forbidden a 1, 50,000 The of discussed an observa absolute K. variable nebula, Kundu star nebula varied main infra con that The and K, in at 1980ApJ...237..506M following The to are number IUE R the taken minutes. particular sured source measured be distance the R the Seaquist find and of line-of-sight latter parameters {OI+ {Nv? {SiiV Cn {Om]+ {[Om]+ Sin {Si ,...,0.4 CJV Hen Fen [On] Fen? Mgn Sn Sin? 0Iv] Cn] Cm] Fen? In The Aquarii. the Aqr estimated, ion described a line III] © relation Ion details E (1) Table have E with cm- using 8 + mean is American size + absorption of + species 8 _v lies of _v of probably Columns 1974). sections. of emission, at 3 transitions, from the sight a of Our from 1 ~ (cf. of prominent moderate absorption the "'245 density "'260 spectral between we by since 0.03. IUE the that II. 1302, 1254,1259 1230,1243 our 1400,1401,1405,1407 1394,1403 1335, 1304,1309 1527,1533 1661,1666 2586-2631 2325,2327,2328 2321 multiplets 1548,1551 1907,1909 1883,1892 1640 2796,2803 2714-2770 2470 multiplet multiplets Falgarone The is low-dispersion Spitzer detector, Boggess give Spitzer DATA due estimated ionized Details (1) pc spectrometer, an we Astronomical pc the conclusions the 1305, 1336 The average in the through resolution below have exposure the overestimate hydrogen to from published in Wavelength (1) features distance (1978) AND (68), (62), (1978) the 1306 eta!. the probable the respectively. of "standard" wavelengths nebula, and deduced CIRCUMSTELLAR (42), (63) at the ANALYSIS (2) the the galactic interstellar hydrogen solar (4) (1978). and 0.2 yield Lequeux spectra lengths are IUE (40), and in to column of galactic wavelengths Sun (A) in em- i.e., identification Bohlin neighborhood R since as the Society discussed ABSOLUTE E "'6 (102), Table the instrumentation plane. 8 Aqr the (Gregory 3 obtained _ actually 10 density cloud of , A spectrum 1973). absolute v medium on 14 density it (41) most plane ~ (1975), 10 is -10 and 1 We the refers 0.1. identify known. FLUXES and • for in 15 model Using adopt likely along mea basis were Provided with at of EMISSION em. and The flux can the the N Wavelength of we 20 of of to TABLE (1240-1258) a (2310-2340) H (1654-1686) a IUE 2735-2770 2585-2640 AND 1402 1336 1304 1247 2802 2328 1907 1892 1640 1668 1548 1527 2474 (3) Feature LINE E identification have small doubtful of various nitrogen all Table Fe the by been formation nebula [0 spectrum sphere emission. 1265 arise other the panion. properties can analysis 1979). 1 8 by The The (A) The extinction _v FROM IDENTIFICATIONS ambiguous II], II Carpenter general above then corrected the are A observed from absorption high-excitation ~ 1. 0 strong However, observed T low-excitation that is (ergs Adopting multiplets 0.05, of are III, evident .$ NASA of be 6.5 3.0 1.4 1.2 8.5 2.7x10- 2.6 4.1 not 3.0 3.0 1.9 because of of lines, R parameters the the 10,000 is R [0 not em Flux checked for X X X X X x10- the X X X X lines (4) the AQUARII observed. which of and excited identifications 10- Aqr lQ-12 10- 10-12 10-13 for 10- lQ-13 lQ- 10- lQ-12 in continuum - companion III], line present, 2 we R as majority in effect. nebula v N s - the Astrophysics this 13 13 12 12 12 12 12 the of are K Wing argues Aqr other 0 the well 1 assume ) fluxes corresponds lines Hen, for against spectra model fluxes lines IV, by of also and spectrum at A frortl and as the the (1979), emission Mg Broad Blended? Blended Si Identification Blended Reseau Observed of observed strongly lower that number 1550 can identified. directly. C servable should N feature feature; ent clear strong from these II multiplets of 0 shown we Si strong nebula. primary similarly with unclear II, n, of those m] the in I Fe follows. also can II A. feature, C S and mark single multiplets long-wavelength because 1750 and our feature feature? (Figs. excitation to also line Data as II, a in v N II], 1304 II ~0.3 from Comments for strongest In of in lines in deduce derived N be These because question We other 0.37 Si and because Si analysis (1). in A M7 Fe the C our Table be our We (5) plausible for and a identification IV] used late features III], We middle of A, 1 II, probably III], cool of the to present System attribute II Total star and cool presence silicon, are Mg magnitudes analysis data multiplet have parameters continuum 1486 in the features lack a lines Si 1309 type Si have C from to hot 1 Fe chromo compact lines almost that mark II the (Linsky for of 2). stars IV, general II IV, because do obtain A flux II spectra 1265 of noted of com A stars have Fe used pres The Si 507 0 and this UV the our Si and not the we ob un (1). of of in in as is of A I, II II II 1980ApJ...237..506M .... -'N 1- Ill )( :::> :::> -' 0 en w <(~ 508 standard spectrometer. at The the represent (2470 features of deconvolved in 1200-2000 R tion was c from tinuum recombination with are cm- continuum continuum. 1407 densities is that mechanism. bination prominent slightly C star, conclude a over 1402 Harrington, ture ably O<( ';" ~ en :!: Cl a: en tJ 0 ~ w factor II). Flo. NASA-GSFC The not Aqr the © 10.0 their IV 8.0 7.0 10 5.0 6.0 9.0 4.0 combined 3.0 2.0 1.0 absolute sufficiently 2 lower for of wavelength A). A since the the American a A), minutes. s- (1548, geocoronal I.-Low-dispersion observed observed obtained feature the nebula toward """ Sll identification. IUE NV of 1 in T has continuum A must We that spectral [0 two-photon A - various LYMAN than a ~ 2 and 1300 the peak of using Si broad flux The 01 between reduction stellar III] On Shortward and a 1 111 15,000 1551 The have ). this strengths hydrogen geometrically by be spectrum, is and are on low long measured this scale in (2321 exposure - continuum The and the by in the 1400 OIVJ La Si entirely Drs. Stecker Q ;:;:; Astronomical ion range 2328 mechanism + A), our 1979 IV mechanisms blackbody selected value a) intensity more H 10 line large (.:510 depends K, stellar wavelengths. is other 1200 continuum programs WAVELENGTH A), Fahey 5 species, accurate However, I data process Continuum c 1500 at July em- and A of will time ( two-photon of observed. aperture Si would 4 ~ and than and due 1216 1978). III] flux feature A and II C La em- C 6 hand, is and (Fig. the 3 25 IV these 3200 A dominate on to only , n] around essentially emission. 1600 there 0 to photoelectrically (1907, A dominates since continuum that to an they in 3 of 3200 MICHALITSIANOS, resolution) is the result Klinglesmith. flux (2325, 1.8.1 ) that has IV] 0 (10" However, cannot it a 1), A weakly and order At the is the lines not have SEC Vidicon factor Society -5 is Iv] a However, (1400, 1700 is are densities F~~. due and A. combined emission the may 2000 x 1400 in 1909 wavelength not little Balmer will if The 2327, and the x varies 20") Therefore, been a of the because flat of be the to we and conspicuous on two-photon 10- 1800 would spectrum explain clear 1401, A A A), magnitude spectrum produce ambiguity 2 what of dominant this [0 due strongest and tempera conclude developed corrected. 2328 densities the • using (Bohlin, appreci 14 that intensity only the Balmer recom arising R camera [0 III] Provided if Aqr 1405, range (ergs peak rises vary con to they por IUE A), the the the the we by or II] of is a a KAFATOS, 1- 5 :::> -' <("' ~ ~ ~ sure and for elliptical characteristic The if lines level mark we peak period change. can If Ilovaisky the time visual ments separation emission companion apparent of observe x 2 n. recombination suggests of density 10 have estimated the by on 4959 prior He by -10 ... '70 Oc:r: ':!: 'en u en w ~ ~ FIG. A the 14 The the = deduce the 260 Merrill physical the 10.0.-----.---,-----,,----.--.-----,------., 3200 time size the found nebular 9.0 is S.O 8.0 7.0 4.0 5.0 2.0 em, 3.0 corresponding be 8 10 further by is around A dependent. to 1.5 cm- mass to ionized 2.-Low-dispersion seen of spectral [0 14 for AND densities pc Si probably size implied was CliVI A Merrill made NASA of be is Ill) the This for x nebular em orbit 1934 substantial position III] properties size and a obtained the a 3 to that 10 and the equaled , 20 of of of "'5 corresponding grounds. whatsoever. continuum argument a ionized central since rise h~s line 7 1400 HOBBS minutes. nebula size hot the of cm- from and is the mass with continuum data the Spinrad binary by the an (1950). found x obtained slightly Astrophysics red strengths lines a Merrill consistent ionized companion A. the of 10 artifact secondary the with and 3 corresponding that 4363 size stars, , of this ratio or observations ionized nebula (0111] 13 C the giants, which of From was The continuum + variations II] Merrill orbit. size in em, no R From the WAVELENGTH toward spectrum density exceeded of (1966) can "the the period A From nebular feature in (1950) above support Aqr of appreciably nebula. one observed. upper observed evidence large the of line that this is the is and also cloud 1:1 with Moreover, spectrum is radial ratio of sufficient long (1950) the comparable to semimajor would detector. have identified this aperture assumed as lower was is from of is limit approximately therefore, Data also to 1Jt1 cannot emission be earlier of in in of nebula electron wavelengths. 1. Fe comparable our R 163] 162] that of of velocity 3:1, by 111 7 x 7 for Additionally, they Mgll unusually roughly found Aqr a visible compared of"' only line found observations limit larger scale its not Merrill nebula System The to model r probably are on with 10 found at be a observations respectively, to between intensity would suggest axis 5 x 5 14 explain hot appears in IUE. unrealistic one a density more expect an in strengths. continuum be a measure size R emission Vol. than to that distance checked question Aqr scale 10 density (1950). orbital with for strong stellar to above which 1 27 Expo 2.1 14 other their L than then 2000 M 237 the the em the the the the yr. an to to to of to = of 0 x a • 1980ApJ...237..506M equal reaching nebula, relative No.2, started estimate observed IC 4959 of observed densities 1979). Merrill similar It continuum strengths, 1980). 10 suppressed going adopt T the the (1) 10 this the scale the puted computed Osterbrock intensity (1974). C tion abundances Kafatos find allowed where particular forbidden factor element due ion B(n., carbon As 4 14 follows Here ~ the The III] 4997 © by relative ~ general oxygen C Z to parameter A .:5 (Cameron 15,000 the to size arguments T) American shown 4363 1980 using from T a using From Cis IV extinction, of (1950) semiforbidden L to to IC to dependent Furthermore, in upper 4959 model lines (Aller the lines a ~ product in A; 10 calculations in and line .:5 of is those element that § be since for maximum 4997." dominate lines), emission a and ionic A x 8 6 trend line lib the K. most observations the (1963). for Osterbrock constant 10 intensity the n. 1922. a the ,:5 A. above, quoted line ~0.1 of for the intensities 15 the limit and Lynch n. the we function C ne (see 1973). of 10 is carbon the the strengths. i) nebula abundances After C are em, data NA,z n. planetary of b) II], densities The [0 ~ and in 3 Astronomical Carbon ,:5 A, 4363 [0 the deduce nebular IV , on Based 2 for Liller various line L in Table Parameters respectively [0 our 10 Emission R II] is above, in the 0 10 involving the we and can m] 3 and were ratio lines the about intensity is • the of electron (1980), 7 temperature the Aqr line II] 8 and IV], is A implied 1933-1934 The is (1970). cm- the have results in em using Line of spectrum Aller be L abundance density 1966) cannot line the range L upon 10 We and 2). parameters planetary obtained less of R of and nebulae, strengths elements it prior [0 - by CIRCUMSTELLAR ~ relative flux 4 used is 3 1922 temperature 3 Strengths , follows Aqr nebular assumed Lines would 4363 ,:5 C Parameters have L distance, x 2 two m] the while for Bely [0 of and density, appears Parameters than and He 10 II] were the (Kafatos by T at ~ to with the be deduced line the was III] 5 (Mattei temperatures different scale .:5 Society and II A 10 for the x 2 .:5 assumed (and abundance Liller the 1934 the be from (1966) under H,B observations that and of nebula or intensities hot 14 x 3 the parameters ~ lines hydrogen to n obtained strengths similar from one normal even • detector the a 10 the em, C insensitive statement B(n., 10 being size. ~ .:5 oxygen 5007 the (2) component agrees and 8 density few only, III] Osterbrock 10 were continuum 14 (1966) and 10 another considera correction 10 would em- from and were methods: particular stronger. the although 4 IC by strength em, 10 that • 8 and For T) to K. A cosmic Lynch years, about em- Allen em of Provided using using using lines 3 4997 fore com from from for with that since 3 and • EMISSION and also line and is We the we the the the the for be - (1) of of to X A to 3 3 a a , , n.2£3 N(Cni) N(Cn) n. N(O N(CIV) N(On) Flux Fcontlnuum(2000 N(Hem) n. Flux n.2£3 N(O N(He1n) N(Cm)a N(Cn)a N(OIV) N(Civ)a N(O Flux Flux collisional important. Fcontmuum the under for 2328 the latter model present). of depends not estimates abundance line [0 the line the Although well helium dances general He would by suggested by (cm- (cm- a NEBULAR Since FROM III] N(O See relative total T III) III Merrill II) III) Ho: (Ha) the nebula [0 (em (Ha) analysis. [0 strongly as strengths (cm-3) A ...... is ...... ~ 3 the ...... 3 •..•.•..•..•.•••••••••••...... line can ...... •.•...••••...... •...... ion m] discussion ) 111] the ) for ...... is ...... have (6563 feature •••••••••••••••••••••••••••••• -3) •••••••••••••••••••••••••••••• an II) (2000A)(ergs trend intensity NASA 15,000 (ergs the (ergs only N(C essentially 5007 assumption 5007 for ...... R model by flux be oxygen is ...... would depopulation PARAMETERS(£ upper In ionic and Model of that Model (1950). A) present, AQUARII cm- constructed He We depend cm- Parameter to A) the to helium II) A Table A of He in on K. as (ergs in N(O (ergs (ergs II abundance and we Astrophysics be obtain the 2 + find 2 A of limit, be A strong our B can s- text. III s- density, C It 1640 Additionally, N(C (Carbon (Oxygen doubly the cm- cm- is 1 continuum generally large have 1 II], 2 cm- cm- ) it TABLE [0 is ) m) by on and that that be ...... data. not we since cannot feature). essential 2 n. 2 III] = otherwise A 111) of obtained adopting 2 2 [0 temperature using s- can s- 2 s- in s- obtained the , by L have 2 unique, ...... 1 ionized. we 1 the Line recombination (5007 Line N(C ) m] 3 ) + 1 X 1 Reasonable some ) ...... this • 2 ) •••••••• 10 ...... then using ...... ionic However, lower be the N(C can in primary 4363 14 Analysis) computed Analysis) The II), Data that case, A) if more em, Table the carbon cosmic 0 no it be we IV) We abundance ...... from ...... obtain N(C the ionic line A IV does than we T= and computed self-consistent use and obtained = System than line have could 2 densities levels the III), ionic 15,000 identify strengths in the lines 1 abundance abundance 0.32 0.53 4.4 0.19 0.81 0.15 2.3 the 1.2 2.0 1 0.55 0.08 0.86 0.06 1.25 10-15 1.5 0.09 0.02 0.36 3.3 5.5 1.25 essentially n. indicate line might all the model observed densities Value deduced 2 N(C ~0.1 L X X also X X X X X carbon carbon is X (if of X of 3 K) abun 10 10- 10- 10 10- 10- 10- ionic does 509 10 10 (the and flux un 55 6 the the the the for IV) be A. 57 be of 7 as 12 12 11 14 11 a 1980ApJ...237..506M 510 explain equation and level tive temperature now forbidden The becomes for using essentially agrees oxygen i.e., temperature rich underabundant from for doubly of of dance even generally Moreover, nebular mass model At nebula. between should only of of M7 15,000 Boyarchuk Assuming The Additionally, On continuity carbon the the this the © to T the L objects giant continuum loss a of alternative the if the American precipitation = the temperature. B compact K, = with of ionized). nebular point, be continuum. function the The the parameters agree 1402 appears models formation 15,000 (1) emission from to x 2 unimportant other in lines), a carbon to singly agree period-density (1975). the companion. 5.0 10 1.5x magnitude. observed be continuum is such factor are the the this to depletion and A 5 however, 10 varied be the the •••••••.•••• X well ii) NOTE.- hand, obtain parameters deduced it 10 nebula 2328 K not feature by 14 deduced 10 ionic T.(K) is analysis, of A more values estimating as ionized, 5 with is (1) Oxygen case, primary "'24 4 em, deduced •••••••• Astronomical of and to •• of in or A of a unique, n. of R in with between A intensity ,, if typical "'50 CO factor mv abundance T* assume carbon attractive values B. interest Aqr. of km it (i.e., since could n. above symbiotic feature Table ••• from the we is L of Line is is ionic from is It the carbon :::::: that star. mainly = the whereas relation s - stellar n. larger not use deduced the escape in but apparent The this suffices collisional general 10 2 x 2 1 of case Strengths be 10,000 line model of obtained into , 2 measured could that to is 6 "'10 the Applying possible 4.1 5.6 observed 1.2 our abundance MICHALITSIANOS, -10 the which are entirely result temperature. n. since "'50 are 10 mainly relatively R*/R0 note than could strengths is of 0 X X x (2) grains, stars cosmic 14 7 6 and atomic oxygen for relatively Society line 10- 10- shown analysis K to-a here IV], result cm- em A in visual 0 varied em parameters it in will speed that and observed. was 3 2 from is to depopulation III - T. our does be a due the the strengths in one 3 3 derived the continuum. (model to , too or distinguish abundance not in 15,000 low (helium Since period in the magnitude. of the for of carbon and our is R* obtained equation from to result analysis, (say say possibly account a appears oxygen can insensi Table ionized • change carbon low mostly He values is abun [0 single result these data. Provided HoT T:::::: stellar B that The L./L K). use the the for B). III] 0.75 2.8 7.4 by of of to (3) of III TABLE is is is I CoMPANION KAFATOS, 0 N radius. 1 is likely triggered the therefore, required bound" dense could classified the will whose we would secondary. slightly apparent companion order This The column cannot r the ture to tribution today. nebular by nebula. places parameters N source 387 Columns the 1.5 3 the by 1 = {s- We We This In L* ionize the material mass-loss find x corresponding L/2 detector be days third for number the mass-loss the is 1 14 18.5 11.4 10.1 12 Mv 10 that ) have (4) nebula be for also apparent of have an stellar However, be AND upper companion. c) emitted lower shown 5 the 0 However, :::::: continuum first rather indicates M excitation the to a K, NASA are assumed by (4) appears due visual and upper column it Properties the 10 already nova. note for = hot the to of that although lost luminosity. column to mass entire 14 and HOBBS rate in is limit than in to compact IQ- rate later, an ionizing be the than em by companion. continuum magnitude be the w- by a limit that magnitudes, in the It was Astrophysics for to (5) 7 gives 10 star the assumed if the stellar transfer since that is unseen is seen of and 19.1 nebula. 17.2 observable Me mv the (5) is 13 flux In 1934 system. 4 "density have of of the a the temperatures probably the approximate give the continuum times possible to ergs star. and not Mv subluminous photons number Table star Table yr- the ionized shown the density that of hot we the primary density it radius been companion is companion the most cm- is 1 is Stellar It sufficiently from luminosity is The stellar attained 10- absolute greater. The the have for too flux companion this 3 is still bound," 3 respectively. in that absolute a an emitted today we 2 nebula 13 of likely n. also we second observed 2.0 4.3 5.0 if lower s- faint stellar a of the Nt(S- model flux Data upper that of eruption ergs Companion ionized. assume as assumed :::::: the 1 mass (6) ionizing nebula this range star, X X X visual show the A - The unlikely mv IQ- low 10 10 10 1.3 primary the arises 1 can suggests to if emis ) by in is limit continuum and strong 43 44 44 column eruption temperatures 1 flux limit. System the B. :::::: 7 nebula its be x as is contributed of "ionization 1934 solar continuum at continuum Me a the of ionize 10 8 2 of It of too 5 x 5 flux therefore tempera observed The observed from that since, Vol. s - 1-3 photons mag. and 7 1200 that is the yr- 10 radius cm- to stellar event, to 1 a units. 10 gives faint most were con 5 A - Me, was star 237 last hot the the 1 the the 4 the all A. be In as to at K 3 is 1 • 1980ApJ...237..506M No.2, region likely 0.7 (CSPN) of 2, the tinuum, brighter peratures for low three white having by be otherwise our appears and 1.5 tially the stellar 10 diagram is continuum. but of observers luminosity, During Aller, Baade, FIG. We 14 and the The responsible seen the the x © the H-R ;5 oxygen stellar oxygen itself ;5 x 5 10 filled hot a L. find a L* American 3.-H-R 1980 occupied 3 observed parameters M W. dwarfs L central and 5 bright optical directly. this the , explain H., give lower diagram star to companion between 10 giant ;5 ;5 the 1942, 10 III. for greater that circles 5 is luminosity white line and reside interval , parameters 4 2.5 7 most the line would and density K, white L DISCUSSION for too decades. stars limit. diagram (WD) Mount by has Liller, the spectrum 0 the strengths emission In location x 5 dwarfs strengthens analysis labeled the respectively. can the of the in x than Astronomical notably 10 Figure faint are at nebular fairly the be dwarf. of 10 Table 14 We implied W. the Wilson times CSPNs ionization central from shown account 4 that required planetary showing (WD). em blue The K, of x 5 1966, 15,000 lines high-ionization 1, also would to transition AND 3 of are respectively. LogT. The the 3 2, the we between parameters Annual shown companion and CIRCUMSTELLAR Osterbrock in our forT* general 10 produce stars R by The M.N.R.A.S., and and and find CONCLUSIONS hot show n. location Table 4 companion the for The to K the Aquarii be belief nebulae of ;5 that filled ::::! companion 3 of ionize WDs Report, provide erratic are that main high, T the the Society correspond = analysis zone the 10 3. light 1928 hot planetary Stellar ;5 that circles an 7 1.5 a deduced grew dense of required, nebular em- H-R nebular and 1.5 state sequence, the 132, (CSPN) (1974). and has Vol. in companion behavior companion this x sufficiently periodicity observable such and could parameters based 3 x labeled stronger, for the nebula. is 10 diagram 337. , 12. a implied puzzled • nebula, nebulae star 10 5 essen 1.5 to much a , from 1934. T Provided tem con H-R 5 REFERENCES The EMISSION and 10 * star not the for the on K, on = in x 1, 5 , with profiles, (Mattei period curve period behavior with comparable the tation short 1934 (1966) is served dwarf observed this to tions nebula strained 0- eruptions of of central tions velocities that the 600yr dwarf dwarf is model reasonable dimensions fested Merrill violet panion and dependence observable information. Bely, Boggess, AA to us sessions. surroundings, constructive Further by From the The We a the We excite the us orB-type FROM by UV VSO outer few interpretation. hydrogen processing most superposed the to 0. made by companion resembled time. nebula is by to of UV of gratefully can is the ago. in by companion. of as star. Baade possibility would and show (1950) an 1966, emission star A., to capable times the the our while observations the be a NASA of most by observed We a in this follows: our for likely nebulosity expansion one JUE eruption R spectrum. "simmering summarize mass by et This directly. bright of Allen emission resident main-sequence 1 M of the to Merrill ionizing are is the Proc. analysis comments We al. AQUARII lines a also 10 for Hubble, which the star data in ionized providing likely the be itself the of Observatory 0 consists ruled of that luminosity 1978, forbidden 14 past is acknowledge ratios disruption to which further ) of Astrophysics Phys. the 1979). white data (1942) ionized that places the supplying different em, appearing R consistent (387 the useful luminosity wish The event and the (1950) astronomers lines Its effects of the creates Accordingly, not that we Nature, is Aqr in out companion rates physical iron the M7 who Soc. and which of a for nova." an R companion suggested dwarf. days). presence, AAVSO of the the wish bright confirmed 27 the attribute result to by observed sufficiently or 1 : 1 light nebula. extends is giant. emission star Aqr "ordinary" and general in improving London, an that especially emitting associated yr observed dominated the 275, of radio, forbidden onset a in thank enough a staff a in is with to and the M7 "mild as monitoring low-excitation white Models separation of The period symbiotic Ilovaisky Since emission of it continuum also has the 80--100 curves thank 1. The during the light has star Data The the for by assistance of the the primary further however, 2 : 1 88, for our Merrill's visible, Hubble's properties J. probably UV lines. ionizing excitation regions. dwarf(,..., the been normally expansion fact on an luminous nova" earlier 1934 the 587. is the the excitation M7 curves brightening faint Mattei with 2' postulating adopted the (assuming model Mira line the km its the emission System such expansion with and approximate and that help around star strengthens text. of acquisition immediate subject referee star properties the and and s observing spectrum the hot the in interpre emission is - observa observa the variable given photons Spinrad P that for became few a nebula. 1 general is offered system of source of • which Cygni visual about cyclic mani to white ultra for white com from light stars con time of 511 The this L ob our the the for the for an be in of to 0 to a a ) 1980ApJ...237..506M Bohlin, Bowers, Bohlin, 512 Boyarchuk, Carpenter, Cameron, Ilovaisky, Engels, Gregory, Kafatos, E., Falgarone, Linsky, Space R. 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