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1993 Extended Variability of the Symbiotic Star AG Draconis Menas Kafatos Chapman University, [email protected]

S. R. Meier USN, Res Lab

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Recommended Citation Kafatos, M., Meier, S.R. (1993) Extended Variability of the Symbiotic Star AG Draconis, Astrophysical Journal Supplement Series, 8:201-214. doi: 10.1086/191751

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Comments This article was originally published in Astrophysical Journal Supplement Series, volume 8, in 1993. DOI: 10.1086/191751

Copyright IOP Publishing

This article is available at Chapman University Digital Commons: http://digitalcommons.chapman.edu/scs_articles/148 1993ApJS...84..201K of Meinunger photometric discovered THE AG Allen © system star ( consider of assign Draconis Finally, high-dispersion high preventing cias, ics 1988) 1993. The 2 1 Max a and Postal Postal ASTROPHYSICAL Ora Universidad to controversial Galactic The (see Astronomy, a symbiotic of be claims (U) luminosity Kenyon American could insights the the the to Subject ofC tions method period separated otic obtained displayed 1242,0 1981 10 address: address: it has AG Kenyon Absolute earlier We study a n by ( to © temporal binary calculated = 1979), period star IV been correct cm- Draconis which latitude November be the American have be Janssen JD De Astronomical of to optical University Departamento headings: into how I yields AG Los & star 3 of for than the helpful Valladolid, JOURNAL AA1302-1306, study luminosity spectral by classified . strong 2438900 phases 1986) of We class Femandez-Castro analyzed and line were Angeles, K3 Draconis model the 1. the the ,..., variability star. AG star 554 ionic Department EXTENDED consists spectra T.;;;:: K4 & INTRODUCTION found 1600 Society. the confirmed intensities III prominent ionization ofSouthem III symbiotic taken emission in and favoring assumes Draconis 0 Vyssofsky binaries: SUPPLEMENT days (I= class. III as 47005 nature Astronomical type, for CA + and abundances confirming IV] 87,000 days, De the All of a high- a the covering 554E 1985 from were of before, 90089. and 100°, the rights Quimica of AA1397-1407 the cool K1 complete Kenyon 0 of Valladolid, whereas a line-emitting AGOra. episodic a it of California, are lines IV] by hot phenomenon levels symbiotic- binary Physics reserved. emission corresponding (BD K time taken February type infrared to has velocity the (1943). b VARIABILITY SERIES, (1987) Oliversen plotted AA1397-1407, for during star be the = Fisica, of the accretion-powered shows been emitting star scale + to change & Printed +41 Received the set by ofK1 and Lutz H to mass and period Spain. Emission 67°922) Department the Webbink 84:201-214, lines to (Roman 1 data. Wilson Society of be Facultad and as When hot found CSI emission to determined °). not and the CSI in region a be primary, available M. et transfers a & stars: proposed. ± during U.S.A. cool 1986 in regions. Institute, The after component. 1991 from function in known ephemeris presence al. Institute, uncertain, Anderson He Friedjung 1 Iyears quiescent been ofthe feature ne et The and are discussed ( Altamore are as 1986) Viotti by to of :s;; al. UV in generally curves no emitting 10 observa­ between HEAO a absorp­ overall 1982). 1987). strong maxi­ X-ray is times emis­ 1242, Si gives et line the m] by al. of et 2 1993ApJS...84..201K and lously to riod. which ( ofJD(active) our observations In§ the AGOra UV rameters, brated. cerned bursts satellite data, curves 2446500. LWR, LWP, Kaler tive within had fore, have Seaton 1979-1989. >..3203/>..1640 1986 202 -0.03 1987) In Approximately, Several 10 far-UV interpretations 2, line 1986 two every this we found cycles long outburst line (1980-1981 occurred is et and and the taken with found These for ( fluxes. maxima are approximately adopt observations 1978, January. al. paper, etc., intensities outbursts 15 Recently, uncertainty been 13 both © LWR spectra the two presented of This (1987), and SWP SWP SWP SWP SWP SWP SWP SWP since LWP7522 LWP LWP LWP LWR LWR LWP years. Sequence 2. the star spectra = LWP are American lines Camera/Image a the Our 1979) had analysis 4 2422660 we ULTRA maxima value what recognized at quiescent work and 20162 25544 37475 27542 23582 37473 This 14640 15710 IUE discussed 5514 3920 16674 16683 11231 12124 554 and and 1930, 29 taken present He calculations -2444600 and (Osterbrock two followed of lijima using cover Number and in 5 of along they of of UV day the presents derived 1985-1986). VIOLET three conclusions. spectra low-resolution ...... and years after eight ...... an similar the associated proposed + EB-v AG of the high- outburst imply period. 5540E(days), the optical and Astronomical three outburst in interpretation (1987) with AGOra. Viotti for cycles high-resolution by = Draconis the§ theoretical and an high- OBSERVATIONS have a of and 0.06. active this maxima 1989), representative for quiescent long comprehensive activity ne, that However, the et photometry 2445000, 2446138 2446138 2445916 2445916 2445493 2444950 2444950 2444820 2447828 2447828 2447827 2447827 2446449 2446449 2444820 of with with 3. Julian low-dispersion using The the and phase Date been al. star L, the We Finally, periods 19801 phases. (LORES) AGOra ( two nature covering we each photoionization 1980-1981 outburst low-resolution 1983) 554 at ratios which (Robinson cycle are of reduced photometric in and determined maxima these while Society -2446100 Cassatella 1981 (HIRES) ofthe KAFATOS, day 1985 primarily in§ of ofthe This value. figures and or two becomes of corresponds 1984Aug3 1984Aug3 1985 1985 1983 1989 1989 1989 1989 1986 1986 1981 1981 1981 1981 study the quiescence binary ultraviolet ephemeris outbursts, the SWP, spectra 4 the February and LIST Date outburst two AA value anoma­ we system. Jan Jan June Aug Aug Oct Oct Oct Oct Mar Mar Dec Dec There­ 1969). period 1985- of SWP, • He of et VSO OF con­ IUE light cali­ EB-v give out­ and 28 28 27 27 18 18 3 pe­ 3 the 11 11 pa­ l3 13 ac­ Provided 7 al. all 14 IUE of is MEIER, II TABLE OBSERVATIONS Dispersion and or cause differ Finally, However, ties the times tra semi-forbidden cited LWR ture tion AGOra. tensity highly tinction wavelength tral partial particularly EB-v spectra for (interactive for emission dispersion duced low-dispersion >..>..1747-1753, traviolet phases fluxes >..>..1548, 1 High High Low Low Low Low Low Low Low Low High High High High High & Tables Figures In not that by the dominant for all resolution quiescent ( Data MARTIN = Table by 10" the ions they spectra and unusual and list SWP(XX1200-2000) the the even 0.06 of low transfer best have in using as 1550 spectra 2A lines quiescent X Analysis AG the 1a-1h of most wavelengths spectra, the are such analyzed much NASA 1, 20") ranges. represent during design resolution (Viotti present and been the and we shown UV 02 08 09 22 uncertainty 04 03 22 20 21 11 Dra 14 16 15 15 states (UT) in lO Start in LWP Si near the spectra case emission function). prominent IUE as analyzed 01 images 49 44 32 33 22 21 show 57 37 37 36 34 low 12 m] 2B 12 18 the have as He line reprocessed language) Facility) Savage respectively. between outburst, values. As et the for N /LWR >..1892, Astrophysics give factor for in with >..>..1200-3200 dispersion in the spectrometer, II al. for LORES have can recorded v and symbiotic have end >..1640 either the 0 analyzed. lines the many (minutes) Exposure 1983). >..>..1238, the both were & in However, m of Moreover, be emission wavelength C at of 120 high figures. 140 been 1979 andLWP/LWR(XX2000-3200) dereddened 05 were been 06 40 50 33 25 20 60 30 15 15 developed lO lO Mathis these >..>..3122, m] -10 data longward seen have quiescence NASA/GSFC. the using quiescent SWP quiescent The obtained of the >..>..1907, resolution corrected stars and overexposed. obtained L We -6 reduction or 1242, from active emission wavelength which These spectra These WP observational lines IUE the and many ( Data larger all 1979) have 3133 1989. A in region, Active Active Active Active at Quiescent Quiescent Quiescent Quiescent Quiescent Quiescent Quiescent Active Active Active Active of detector. most State absolute Table System and and data in LWP/LWR general. high-dispersion and with N fluxes 1909) or the has X1700A of for for chosen the between System and IV] SWP, All outburst lines method active routines -0.1 of All RDAF the active recent a shown the line the interstellar 2A, range. LORES He which limiting are absolute >..1487, He LWP line He Most parameters is represent prominent large II (e.g. LWP intensities A IUE highly very periods II phases, large outburst ITF >..1640 II (Reduc­ were with for intensi­ The Vol. phases. spectra are in >..3203. /LWR fluxes, of mode N weak spec­ spec­ aper­ C high IDL and (in­ and line -5 the be­ ex­ ex­ m] re­ ul­ an 84 IV of is a a 1993ApJS...84..201K took No.2, spectra and selected state (SWP in LWP representative active 1 e place in 3920) 27542, ( 1993 were SWP because 1981 and in © represents C 0 0 0 0 Mgii He He He taken [0 He SiiV Si 01 C 0 C C OIV] N Nv Si Si He NIV [Nev] NIV] [NeiV] 14640, quiescent LWP August. of American 1986 II] III III II III III] III IV III] • b III] III] II II • c b II] II II II II II they Saturated. Broad Weak Saturated. ION Weak ...... the ...... IoN ...... in ...... 7522). January star L have feature. feature. WR feature. 1984 The the states in the 11231 activity Finally, quiescent August. Figures Astronomical is best of 2818.7 2797.9, 2795.4, 2733.3 2511.2 2470.3 2326.9, 2252.7 3203.0 3132.9 3121.6 2826.6 1892.0 1746.8, 1660.8, 1640.4 1574.7 1548.2, 1397.2, 1334.5, 1301.1, 1264.9 1238.8, 1906.7, 1808.0, 1718.5 1601.5 1483.3, 1393.8 shown 2802.6 1404.8, 1752.1, ) Low-REsOLUTION the signal-to-noise show >-.(Lab) and (A) Figures Low-REsOLUTION The 1b star. EXTENDED 2328.1 1335.7 1304.9, 1242.8 1666.1 1550.8 1816.9, 1908.7 1486.5 786 1749.6, 1748.6, 1399.8, state >-.(Lab) quiescence. in and (A) 1407.3 1753.9 the next These Figures star of 1 1f(SWP 1306.01 1817.4 1401.1, Society d outburst AGOra, and in spectra ratio LWP/LWR an 1 c Figures >-.(If! 2816.0 2728.0 3197.0 3128.1 2794.2 2470.4 2327.7 2508.0 2250.2 2833.2 3116.7 VARIABILITY SWP 1h outburst (A) and and 23582, which (SWP E) • these were AA >-..(JUE) 1601.7 1748.8 1576.1 1664.0 1639.3 1548.3 1401.0 1263.2 1303.8 1238.9 1891.2 1910.5 1817.9 1718.4 1485.5 1393.0 are Provided (A) 1 1a TABLE2B TABLE2A 1200-2000 >-..>-..2000-3200 g Active 11231 11.5b 13.9b 6.9 4.4 4.0 5.0 5.8 5.9 3.2 1.4 The wavelengths states. October. HIRES vary medium 37473, SPECTRA OF Active 41.0" 57.9a,c 21.8" 56.0" Tables 14640 0.6 0.4b 0.6b 6.5 6.7" 2.2 2.9 7.5 1.4 by emission SPECTRA only AG Figures the LWP spectra excitation 3A OF by Quiescent DRACONIS NASA AG OF for and 3920 0.6" 0.4" 0.9 0.3" 0.2" 2.8 16683) Quiescent 1.1 1.9 1.1 line factors (10- 2a-2b, 23582 AG 22.5" of ABSOLUTE DRACONIS all 0.2b 0.5 0.3 0.5 0.4 4.6 6.5 7.8 (10- 1.8 1.6 1.7 3B fluxes ABSOLUTE 12 highly DRACONIS the ions ergs give 12 Astrophysics show of ergs 3a-3b, HIRES cm- (Si in the -3-5 FLUX excited cm- the the Active 2 7522 FLUX 10.4b 16.5 IV+ 110.oa.c Active 0.9 27542 6.7b line 2.1b 2.8 5.2b 3.9b s- 49.9" 53.9" 32.3 2 9.0 0.8 0.4b 8.8 2.0 2.1 5.1 star 4a-4b, l.Ob 1.1 1 HIRES s- SWP, ) between 0 intensities 1 ) individual in IV], a LWP, 5a-5b, Data SWP quiescent 0 Quiescent Quiescent active III]), 16683 37473 22.9" 0.9 0.7 0.1" 0.2" 0.1" 0.2" 0.2 0.2 0.9 2.5 1.8 0.4 0.1b 0.4b 0.2 0.3 9.4 0.7 7.9 2.5 4.5 and 1.5 1.0 1.8 and wavelength ions System and and corresponding and LWR phase ( N 6a-6b low quiescent v, spectra. in excita- region C show 1989 IV), 203 1993ApJS...84..201K observing in Note ergs FIG. the cm- i.-Low-resolution variations dates 2 s- ~ ~ ~ it ...J ~ ~ !!!. b. NUE © !!' 1 ( A 1981 E-12 E-13 E-12 E-12 E-12 E-12 E-12 E-12 E-12 E-12 E-12 E-12 E-12 E-13 E-12 E-12 E-12 E·11 E-12 E-12 E-12 E-11 E-12 E·11 American E-11 - 1.5 1.2 3.5 2.5 1.5 2.5 1.2 3.5 in 1200 1 2 8 2 2 4 1 5 0~------~------~------L------~ 8 6 3 5 2 6 0 0 0~------~------+------~------~ 1 3 1 1 • ..------,------.------.------, "X" the August, NV I UV indicates IUE continuum 1984 1400 Astronomical spectra August, a cosmic of between WAVELENGTH CIV AG 1986 I ray 1600 Draconis Hell January, hit. activity I Society (A) obtained and 1989 1800 QUIESCENT QUIESCENT SWP37473 quiescence. SWP23582 SWP27542 SWP14640 October). ACTIVE ACTIVE • in Provided the d b c a 2000 SWP All These spectra "-"-1200-2000 E-12 E-12 E-12 E-12 E-12 E-12 E-1:! E-12 E-12 E-12 E-121MAWI'Irlta'I'Jirl~~·\#ll-.1200-2000 the the 20162 Provided TABLE f, TABLE II II XX2000-3200 2794.33 2801.54 2509.92 3201.43 3131.35 3120.08 Absolute X(IUE) flux• 34.5b (A) 16.2 0.2 0.3 0.1 0.7 0.4 0.7 2.0 4.5 5.0 6.0 9.0 0.8 2.7 1.0 1.0 1.6 1.2 1.7 3B 3A general, C tion would SWP sion 0 in LWP nearly from outbursts 1980-1981 ACTIVE OF IV Finally, SPECTRA the IV], by of SPECTRA lines flux. 5514 N camera line AG lead the a Absolute N the v proportional flux• decade 13.4 n which from 1891.09 One 1750.19 1883.16 1810.12 1751.03 1907.84 1665.29 2.3 5.0 3.8 3.2 1659.99 1550.12 1242.29 1639.54 1393.11 IV], 1547.44 1485.75 1406.65 1404.09 1402.07 1400.42 1399.04 1238.21 1.8 X(JrjE) OF maxima in fluxes DRACONIS to and (A) NASA 1238, OF AG is Figures maximum and feature AG -1% 1979 SWP 1985-1986 is and DRACONIS are ACTIVE 1242 apparent DRACONIS of 0 2801.45 2794.34 2510.96 3201.54 3131.48 3120.26 X(IUE) Astrophysics 25444 per higher June the 8a-8e to the III] (A) clearly to the Absolute year line LWP mean QUIESCENT uncertainties 139.0b 0 flux• fluxes 26.1 to 30.2 14.3 0.6 0.3 0.7 0.2 0.3 0.8 3.5 4.0 8.3 9.3 2.3 2.9 1.2 1.4 1.3 1.7 in C outbursts. I we for (Bohlin >..>..1302-1306. 1989 fluxes emerges IV 16674 these show sensitivity ions plotted Absolute flux flux• November. 0.7 0.1 0.4 1.5 1.0 1.8 with plots, of & for emission Data here: Note of wide Grillmair 1750.33 1891.13 1748.95 1883.25 1751.43 1665.29 1659.95 1639.57 1550.05 1547.50 1404.13 1485.74 1238.22 1406.66 1400.45 1399.00 1393.08 1242.27 X(IUE) the as a (A) -10% since degradation variety a The line occurrence the System ionization SWP function QUIESCENT lineN the close uncertainties fluxes in 1988). of 37475 data the states correla­ Absolute v, are, of in stages flux• of emis­ 25.2 span This 0.2 0.3 0.6 0.8 0.7 0.2 0.6 0.4 0.5 2.4 0.8 4.0 6.3 1.1 1.4 1.6 1.7 0 205 the the the of in I, 1993ApJS...84..201K in phase. affected ~ < ::::> --' --' X u. ~ ~ ~ 'E < 0 --' en 1- < Ill .g u. ::::> ::::> 'E --' w X ~ "' ., < !:!' 1!:! 3 u. ~ ::::> 'E --' X ~ ~ "' FIG. quiescence FIG. FIG. E-11.----,----,-----,----,----.~ E-11 E-11 E-11 E-11L----L----~----L---~---~ E-11 E-11 E-11 E-10 E-11 E-11 E-11 E-10 E-11 E-11L-----L----~---_L E-11 E-11 -1 -1 -1 1390 3 4 2 1 1546 0 8 2 4 Note 6 1 26 28 1239 1238 1236 0 4.-High-resolution 8 6 3.-High-resolution 2 4 1 2.-High-resolution by ,------.-----,------,-----r---- the the ( © 1983 presence P American 34 1398 1394 Cygni 1547 June) CIV I of NV profiles I a Si C N v reseau. IV IV WAVELENGTH WAVELENGTH 1548 WAVELENGTH H1238.8, and >..>..!548.8, and Astronomical OIV) I ACTIVE ACTIVE ACTIVE 0 the OIV) IV] I double-peaked ( 1242.8 1402 X.X1394-!407) 1550.8 1550 1241 (A) (A) (A) ___ CIV I spectra doublet Society NV SWP 1406 SWP SWP 22 1244 1242 1551 _L I >..!242.8 observed emission in ___ 15710 25444 25444 AG emission Dra in • 1410 line ~ 1552 a AG 8 ~ Provided observed spectra Dra line during it ::::> ,[ ~ ~ < .g ::::> 'E --' X j!:! in in $ 1- < Ill < 3 u. ::::> ::::> in 0 --' --' en X w ~ ~ ~ 1- < it "' ::::> 'E X w ~ 'E ~ ., "' AG (a) Fig. E-11 E-11 E-11.----,----,-----.----.---~b E-11L----L----~----L---~---~ E-11 E-11 E-11 E-11 E-11 E-10 E-11 E-11 E-11 ~11L_ E-11 E-11 E-1o,------,----,-----.----.---~b -1 by -1 (a) -1 1390 3 2 4 1 1546 0 1236 an 8 6 2 4 Dra. 1 0 4 8 6 2 1 2a l"''ou,...)tl",.,,r...J'o-.14' an the active (SWP ___ Fig. active phase NASA 3a state 15710). 1394 1547 represents 1238 L_ ( CIV 1985 I ___ NV ( Astrophysics 1981 I The March) activity WAVELENGTH 1398 December) 1548 WAVELENGTH red 1239 WAVELENGTH ~ QUIESCENT QUIESCENT QUIESCENT component ___ and ( OIV] 1985 I (b) and 1402 1550 1241 March), _L a (A) (A) (A) Data quiescent (b) ___ of CIV the I a quiescent and doublet System NV SWP 1406 ~---~ 1551 SWP SWP 22 1244 1242 state I Fig. 20162 20162 20162 ( 3b ( in 1983 1983 was Fig. 1410 June) June) taken 1552 b 2b is 1993ApJS...84..201K as when ble prominent for ever, discerned ing During values the regions region when Note X < -' 1- m :::> !:!:!. :::> (/J -' 0 'E w u. X ~ < 1- < 3 !:!:!. g w 4 X ~ ~ 'E ~ ., "' FIG. 10- the values interpretation lower E-11 E-12 E-11 system E-11 E-12 E-12 E-12 E-12 E-12 E-1~ E-12 FIG. the 1.8 1.4 -2 -2 the 2792 1658 12 6.-High-resolution the 0 6 2 1 C 2 6 in above near closer quiescence r----,------.----.-----,----,---.::o L..----'-----'----~---'-----'------' broad ergs 5.-High-resolution overall IV the density from line of gap in © is the cm- range C apparent mentioned to quiescence above 2794 American fluxes IV in Mgll this 0111] dependence hot 1660 the 2 I I regions theN of above s- 20-40 or figure. hot component the 1 inverse a are and low-flux 2796 Mg certain v gap star 40 saturation low. X (circles) further 0 fluxes possibly There 1662 WAVELENGTH WAVELENGTH n P X 10- III] Astronomical in ;\;\.2795.5, tends where Cygni 10 There ACTIVE ACTIVE the ;\.;\1660.8, outburst 12 value, 2798 for - formed away from is ergs 12 to and C inN profile C a • values is saturate IV This gap 1664 2802.6 IV is EXTENDED cm- we (A) (A) that in and an IV]. is states, 1666.2 2800 during in in outburst emitted. would 2 then in interesting Fig. observed s- there the 0111) N In the for I the Society 1 spectra v Mg outburst, we 6a as C 1666 SWP are LWR I the hot fluxes 01 indicate 2802 range II well (LWR is IV are One (triangles) in observing 25444 a and fluxes VARIABILITY 12124 source. outburst. shown AG as distinct observ­ feature as 25-35 possi­ 12124 • a 0 how­ Drain well that 1668 2804 less a for III] Provided in AG ). (a) Dra an < < !:!:!. (/J -' -' 0 w 1- m ..\! :::> :::> 'E X u. l < !!! 3 !:!:!. g :::> 4 X u. ~ !!' sion all dominated -' the weakness with ., this tion "' active during OF As The The E-11 E-12 E-12 E-12 E-11 E-11 E-12 E-12 E-12 E-12 shape by 1.8 1.4 -2 -2 presence section. lines, disk 2792 1658 ionization 6 2 1 8 6 shown phase AG L-----'------'----~---'-----'------' .----,------r-----,,----,------r---cb""' SWP results (a) the of parameters or with activity ( DRACONIS by 1981 the NASA The spectral absence in 2794 of ofUV Mg intense 0111] the 1660 3.1. Figures potentials UV December) I I strong associated ( II 1985 primary continuum. UV observations range Astrophysics of are 3. 76 2798 2796 resonance March) the permitted 1a-1h, DATAANALYSIS Lines presented. 1662 WAVELENGTH WAVELENGTH greater and ;\;\1200-2000 emission nebular, semi-forbidden QUIESCENT QUIESCENT and (b) and the a than and (b) and quiescent phase emission UV Continuum 64 1666 1664 stellar, arising quiescence (A) (A) analysis Data weak 30 spectra 2800 clearly e V. 0111] and lines from intersystem lines, I System Mg We are ( SWP of I possible LWP 1983 ( shows 2802 II and 1989 spectral lines shall AGOra described the 20162 16674 June) the October)­ the general discuss accre­ emis­ over­ 2804 1668 b UV 207 are in 1993ApJS...84..201K continuum only continuum lengths, have have K. -< (1980 events. 0 -< ;>,.;>,. ~ ~ ~ ;! -< 0 ::; 0::: 208 z g > 0::: ~ N ~ 0 ~ ~ :II >C :II >C FIG. 1660, 10.00 20.00 25.00 15.00 20.00 30.00 If, 10.00 50.00 40.00 60.00 0.00 5.00 2.00 1.00 3.00 0.00 4.00 6.00 0.00 5.00 the obtained 4000 fitted November-1981 however, Line 7.-(a) 1- 1-- 1- 1-- 1-- f+ - + . + I- ,- I !+ !+ i I 1666 ! I ~ 1-- 1-- + consistent short fluxes the beyond © + low-resolution flux 4500 + + N v N wavelength + It t American It a + + I + + SWP we + + are lower +* + ++ }..}..1238, + + distribution + ++ + assume in with 5000 -A1600 + November) tl + tl ,t continuum units + limit + + + 1242, absolute hot AA1200-1600 of 5500 that ++ Astronomical I to + I I + A I w-• stellar (b) + + and rising the (cf. there fluxes 2 0 + with 6000 ergs + ( temperature I Miirset + 1985 It I I It + I ;>..;>..1302-1306, blackbody t + + + + cm- of towards :t + is + blackbody + AGOra February-1986 + a part + 6500 + 2 + + tl + + + + + t, substantial + s-•. I + '+ + et t I + of al. Society KAFATOS, plotted shorter emission. the 7000 T 1991) (c) I I I I I * I curves SWP ,_ 0 January). against IV] nebular 7500 40,000 and wave­ JULIAN I • I I I I I }..}..1397-1407, con- and We Provided fit time MEIER, + + c b • 8000 DATE + Note ------(Julian -< ! -< 0 ! ~ ~ ~120.001-- o ;:: 0!: ~ ( that 200.00 160.001-- the 40.00 the with higher reported ao.ool tinuum, 1~00 20.00 10.00 + 30.00 0.00 2.00 4.001- 8.001-- 8.00 o.oor---+=--+--- 0.00 2440000 (d) We 4000 & the Date). by 1986 1986 I- + + I t + + ,----,----,---~----,,---,-----,----,---, the C MARTIN emission in find IV the DAYS) Zanstra we a + the + }..}..1548, outburst outburst The 4500 + similar + ,t + It I+ + that NASA t find + + + ++ + 1981 arrows + + + + + line ++ + + + + + 5000 a 1550, the + method tl tl + t maxima outburst I (Figs. increase higher has I + represent + + + + Astrophysics + UV (e) not 5500 1 He 1 + I limit I ~----~r---·~~--+~---4~--~ occur I results continuum c been studied + (Figs. in the II and }..1640 the + 6000 + between UV of + + + + 1 I I (see + t + 1 g). T + 1981 + + + outburst + a + + (often + * and + + + + - Viotti below). + + Data 6500 +I the level + + + + t continuum. T + by 80,000 1 saturated), arrows e) periods these et was as System 7000 al. I I compared for K. of authors. considerably ( both 1984) and This AG 7500 However, _l I I (f) Draconis Vol. outburst agrees + have with + 0 N v N +I • 8000 ··- - - III] 84 i 1993ApJS...84..201K absolute the Dra. ;>..;>..1397-1407, 10- No.2, FIG. 12 circles The ergs 8.-(a) 1993 fluxes solid u:: ~ g 0 :!! :!! l8 -10.00 = E u:: ! z ~ u:: 0 ~ ~ ~ 8 ::! !=! !=! ,;, -; u:: u:: 0 0 X ~ ~ ~ ~ ~ ~ :::0 - :::0 X ~ :::0 :::0 X cm- represent 12.00 60.00 50.00 30.00 25.00 20.00 10.00 12.00 20.00 40.00 10.00 15.00 10.00 0.00 6.00 2.00 4.00 8.00 2.00 4.00 8.00 6.00 5.00 5.00 3.00 2.00 1.00 6.00 4.00 © triangles 2 (d) plotted 0.00 s- N American 1 N • V 0 c9 & Cb 0 10.00 fluxes 0 I] 0 o 0 0 ;\;\1238, • ;\1487, represent o•~ against • .~o • £oo • \.eo W' 0 • • 0 0 0 20.00 taken 0 0 C 0 0 o 0 0 0 o • IV and 0 C 1242, fluxes Flux Astronomical 30.00 IV in (e) }1.}1.1548, quiescence. Ill (b) 0 taken 40.00 1548, .. m] • • •• • • .. • 0 • • 1/l. • • }1.}1.1660, • • t • • EXTENDED during • • 1550) • • • I 50.00 1550 •! t • ;>..;>..1302-1306, •• • .t• • • The •• •• • • • absolute • 60.00 the • • 1666low-resolution • • • units Society • active • • a • e 70.00 b d a c of flux phases VARIABILITY (c) fluxes for • 0 and AG are Provided IV] lower the than works while were possible al. The II tion mates, sity overall This Flower from emission only different nated 10 tion high the /(>..1401.16) in lines The P tion ple profiles Note strongest structure affected are component, ity increases January He the nent nebula 2a >..1892 ment with >.J.2795, >.J.1238, >..>..2000-3200 1242 Cygni >..>..2795, OF The As In A P A 5 ( any by -10 (SWP Mg multiple profiles star. ratios formed. 1987) Mg II weakness to features ~v- higher the found Figure estimate semi-forbidden -20%-30%. are in the mentioned theN resonance the densities AG an by doublet and drops the n.- 6 weakness of Cygni surrounding II obtain & during SWP profile by II outburst "density The optically the 2803 unique, cm- times, 1242, is lines. lines (Fig. explanation the imply 0 Nussbaumer intense has 15710) towards line 70 2803 DRACONIS Viotti C the to as v being NASA 6a(LWR densities structure dominant The we and IV] (cf. 10 weakness 3 doublet m] km 15710 dramatically, outburst profile calculated is be ofSi in (Fig. an wavelength N in 4b) the due presence than fluxes vs. C We 10 obtained uncertainties higher a doublet ratios before, peculiar density-dependent the near Viotti ofN >..>..1907, v /(>..1407 both UV (Fig. s- stratification," suppressed cm- thin et estimate 3.2. a density IV permitted . 19801 m] >.J.1238, to 10 longer found 1 P 1f) the (Fig. those Astrophysics al. ejection • lines is >..>..1548, found ratio of None continuum the the were 10 Cygni 12124) III], 3 and to active ratio were emission 1g) ofMg or Nebular than et (197 ( (Viotti clearly star, the the become of cm- n. during 1983, 1981 double this presence ~v- nebular .39 quiescent 2a), in al. 1909 Si obtained that which C suggests ranged region. a of from wavelengths obtained UV oftheC of 1242, >..1242.8 calculated. 5), while the here most where m] III], reseau. profile )/ and 3 in of 1983; II lines we feature the in ). 1550 outburst. 2: although /(>..1401.16). exhibited et 1984) >..>..2795, the are Parameters 200 a some could spectrum features outburst we range profile the 1. pronounced. In show the and or quiescent contained shell flux C electron al. (optically may from other of He This the and that Lutz very these 0 derived from more phases IV the is IV and km Si line This component line interstellar 1983; is Data C by and manner. IV] be evident the distribution 10 II >..>..1548, m] >..>..1548, with be of Mg C III]. during given 2 weak could 2803 weak this s- This electron two et in due different >..>..2358, He semi-forbidden in 10 in ratios to (Fig. the may intensities the multiplets of IV lines, than Mgii Lutz the 1 density. al. the ::;; exhibited Lutz states, electron However, which 4 thin) II a theN System enough structure AG the These and II to aforementioned 0 >..1242.8 is n.::;; during which by in velocity semi-forbidden 1987). be indicate reason in emission the active 2a). In >..1640 a a one 1550, 1550 IV] /(>..1404.81)/ finding et >..>..2795, Mg in both et Dra suggesting the density high-density false LWP/LWR the Mg ratio quiescence, 2511, while cameras al. is 1986 10 v Figure line noticeably al. Following lines site In II is informa­ could were densities in the doublets result is u phase P >..>..1238, Because >..1238.8 and II ( compo­ spectra absorp­ Lutz may for greater inverse separa­ are 1987). of 1987). Figure domi­ multi­ cm- inten­ much Cygni agree­ ratios activ­ asso- Si 2803 2730 (i.e., 1986 lines lines esti­ 2: Mg 2a the 209 the the m] be of be et 1, at of 3 a . • . 1993ApJS...84..201K that Assuming L- star (Kenyon choice as distance log Webbink tional vious 8000 star component. emission calculated diameter ing K the the stood Michalitsianos, the form emitting and diameter n; the tional ( 1991). density the ciated 10 nebular 210 Osterbrock We The and a K a 10 L ( region to spherically Si systems R geometrical semi-forbidden n Rd cm-3, 3 Te K. 10 of h• to 1 work ton; used Allen to m] the with star of 20,000 The absolute - can 12 is streams, ~) emitting be whereh dpc n; region path-length of -10 ( the and 1986) lines 1.7 relative solid M no 1984) a d and the © L Kepler's the the apparent L be (Mtirset (Nussbaumer ( lijima = 1 = - - 197 3 value 13 1976) 3 X greater d h• K, American 1 - largest used 700 we 3.3. disk, uniform 700 emission an angle em 2.4. & d ( and the 10 intensities 1.4 effects 4), rings, Kafatos, and 2 < if region. 1-5 respectively, to Feibelman find for extinction 12 pc we should for 1 (1987) to corresponds distance. pc line The Properties Mv- etc.). the law X where em, et L. Slovak and is of characteristic than M a and estimate seth= or these Te 10 (Anderson a spherical of al. We line the 0 case. to strengths spectral lines. For factor or absolute a Michalitsianos, 13 Since and has 1982). Te observation. be 0.03, disk, 1991). of 20,000 PARAMETER L determine Astronomical reports estimate log region. of em, et estimates - densities R* R* L* L* If of In considered 1982) been 1 is the sight M which Due al. of the depending (Rd~)- and the the (L 10,000 (L EB.v (R (R to we the the respectively. 2 which classification region, Kaler the ( 0 0 0 0 UV magmtudes are - Also, 1987) ) characteristic et ) a K ) ) line This size a made and to region, have substitute we general the HOT path K5 Primary = are similar 1 al._ and the the proportional up unreliable. lines K, ( 0.06 M intensities of can the is In radius expression where 1987) III COMPONENT work leads to typical as 1981; & on 0 to overall length the the comparable semi-major on may general, however, equality 1.4which (Iijima take (T• giant always lower Feibelman case, and corresponds -5 the Society value the_geome~ry region resulting values of KAFATOS, to are also by of Lis = Mtirset be into of 147.0 length basis X the the through the Te 50,000 weakness for 68.0 L are limits. Kenyon mv- 0.2 0.1 EFFECTIVE concludes the write symbiotic as 10 is for applies ( 1987) to is = PARAMETERS (e.g., K.afatos, for primary the primary is electron account propor­ propor­ accord­ 10 of low 10,000 under­ axis size values to n; in R 1982) of K) • et cm- ne- 9.44 cool it to pre­ Our 1 the the the the the Provided LQ we al. of as m as or ?f a. & of Quiescent TABLE4 MEIER, a TEMPERATURES 3 Active OF (T* AG the R* should IUE found fected quiescence large gest likely June. then account estimate intensities tary tained photons sianos, find cases effective mula tent photoionize T T ing 200,000 that nosity N; N; and mer not photons Stromgren 13.6 = 133.8 * * VALUE & The Kenyon 100,000 We 62.0 DRACONIS (HI) by at 3 = 0.03 0.04 (beyond properties - - greatly nebulae with lines & arise out Te eV) MARTIN uncertainties uncertainties used the (Allen four to These a by theoretical of 150,000 calculated from the Mihalas be T* 166,000 t.L & = radius - K) the if be or from for hot the temperatures K) the the - from Hobbs taken 10,000 and are different 1 the to & and 4.4 relation. NASA L) in different a FOR Lyman the the the sources 1976) region the vary 1.0 component secondary number calibration Webbink white obtain of the subject R* 3.4. size X higher for the 2-3 K. a ( ASSUMED Lyman K. as observed nebula. X size 1970) ionizing blackbody. 1980). 10 K results the = active (T* periodically N; (since Finally, since to estimates and 10 Stromgren times These ofthe times, Properties 0.02 45 dwarf. we continuum Astrophysics With of from . estimate an of 46 = of to number s- for Therefore, 210.0 show error find luminosity limit) 150,000 (1984) 97.0 s- ( hot the and Table the 1 found ionizing ~with uncertainties estimate 0.01 0.01 the errors T falls greater H-R source for emission th~ 1 between authors assumed * Mtirset lijima the for star. the nebular absolute relative quiescent We to that quiescence. mentioned = within photons R* weaker of between diagram 4 of K) in relationship, estimated the within and found number photons, 50,000 gives during a then These may the photons and the the Tables (1987), ionizing of corresponding et consider active of line 1979 values signal-to-noise errors the Secondary emitting al. overall the Data values emission L*, the be. used these lines of in R* phases a values ( R* the intensities. ( central factor cf. K, of 4 September their above. -20% The number 1991) secondary the state N;(H number N; = and on are of photons the K.afatos, hydrogen 1980 = when values System in the number 100,000 0.014 which (H radius of ne the results stellar 0.01 related region will 5 Tables of blackbody of line stars give the I)= The for are hot I) - outburst temperature the 3-5 other taki~g of required at of al~ow ~ ~ These ratio. star. 10 flux the and subject results and using Michalit­ models IS values star of of~u~­ N;(hv size different of L by ionizing ionizing star photons of K, 4 10 Vol. consis­ dunng ( plane­ stron­ is hand, wmz­ and T lumi­ t:.N; is In cm- what us 1985 very The L in~o and * and line and for­ ob­ . the af­ all 84 to ~o in of to Is = ~ is 5 I 3 1993ApJS...84..201K No.2, N;(H cence detector. lar with tember tent that that II hot III using by N;(He (Seaton fluorescence cence calculate also outburst These tion temperature (assumed continuum agreement outburst The Mtirset this to nebula [the part 54.4 We -8.7 -0.0020, 105,000 to From We estimate ;\3132.9 taking periodic secondary N;(He find be with method temperatures eV)]. of Bowen of He all the the line X are, I) phase. have 1993 is II), to et He the used levels and K) II the 1960). 10 AL R* R* Lr/LF.dd M_ Ld(L.,) Lr/LF.dd Ld(L.,) because are ACCRETION higher thick The that N;(H previous the al. L* modified stellar) which flux however, Lyman The with we 42 II the used continuum 8 8 (R.,) (R.,) II) being © fluxes variations and resonance-fluorescence number ofT* the ( to (M., (M., higher photons Our = the Parameter s- Lya ratio 1991) estimates can T is n -3.2 ( in American effective 0 estimate .. 19 ...... 1 Osterbrock Mtirset The I)/N;(He R* * temperatures ...... > number the corresponds yr- yr- ~ for the ...... of line III at values present L photons being estimate and ~87,000 continuum - 10 estimates of ...... 2 DISK 1 1 0 = Zanstra line uncertain substantial than ) ) the point modified observed quiescence. X He yield of 5 43,000 in •••••• N;(H •••••• 0.009 intensity is in K. luminosities 10 et at temperature same Tb ionizing contributes 1985 PARAMETERS of II Tb the of luminosity: -0.5 in ofHe .. those 43 al. 1 in out, . . . . . 1 Lyman ;\1640 II) TABLE the = T = converted R* 1989). the s- a I)/ Astronomical K R method ( number the K. I if * 40,000 June. to wavelength 1991). -0.0032, 00,000 Zanstra due 0 ;\3132.9 less 1 of the photons, 2.0 7.0 N; number 1.0 1.7 (Osterbrock found during and indeed contribution II for obtained temperature ( is The a temperature SWP Active T hydrogen 127.0 must T (He Lyman 5 84.4 lines, to X X X X Zanstra divided * sensitive Moreover, 0.3 2.4 active * Mtirset K L* FOR -0.31 K 10- 10- 10- 10- ratio obtained line = the of This L* are of EXTENDED - in II). into method region the 125,000 quiescence, flux, 5 3 6 2 found be the of AG recombinations photons N;(He uncertainties and = 10 of the not after continuum during times ( is During method He nebular. cf. temperature by 10 of et hot Bowen photons 5 DRACONIS 0 a 4.4 5.9 3.1 therefore, 5.1 part Quiescent 1989). from of K present a ofthe al. in lower the Pottasch L the Society shortly here II III the for 55.9 a 37.1 of component. x X X X K), corresponding 0 the 0.2 II)= and 1.6 reported ( disagreement longer Lya quiescence below in total of ;\3132.9 10- 10- 10- 1991) w- -37,000 overall outburst Herr;\ the continuum fails during resonance­ are blackbody limit in with In spectrum. 1979 the N;(He Since 6 produced 7 3 3 VARIABILITY N;(hv work photons photons in after nebular fluores­ implies general fact, consis­ 1984). 228 quies­ found of of the LWP • simi­ since 1640 frac­ else- Sep­ can the the He we Provided by K. an II) In as 0 A ~ is where presence M solar served accretion luminosity Kafatos, where, and LTI ties therefore, the boundary for (for applicable ofthe quence-type dwarf Tb values hand, we 3.5.2. kL OF 0 For Alternatively, 1 Assuming For It • by the obtain equality yC LEdd 8 In by of is constant masses, M* R* LTI AG Ld R* this and photoionizing this JVL unlikely Tb of Tb blackbody what presence e.g., the 1 3.5.1. Mtirset AGOra N;(H N;(H 1 is Michalitsianos, 1 R* ~ ~ ~ ~ of is, disk LEdd = 8 = discard layer temperature, DRACONIS the temperature, M* 1 the (disk if R* 7.07 6.9 8.44[N;(H 5.5 NASA Ld 0 Kenyon an again, 100,000 during sign follows M* Ld 100,000 the star (solar-type) times I) I)= Tb Tb 3.5. around results accretion [N;(H ~ ~ ~ ~ that et [N;(H accretion is 1 = the of of 1 x + are 1 = = applies. ) ionized 63.5 52.9[N;(H 1.0 12.7[N;(H al. the continuum 4.4 10 the the such boundary because 10- an 40,000 the Accretion the photoionizing larger K we Astrophysics ( & flux markedly 46 and x luminosity K, shown 1991 I)/ [N;(H X radius I)/10 accretion the 4 (cf case active I)/ secondary s- Webbink 10- adopt secondary the corresponding M* the & 10 rate, 10 we was region the disk. 1 than 10 Miirset K secondary ) . Fahey 45 45 3 in 45 1 Tb M* corresponding 45 find (active (N; Lower-Limit of layer, assuming I)/10 in I)/ I)/ ] (average) and the s- ]31 Disk M* arises different 1 1 ]£ the star. 1 the different We the = 1 Table 2 1 10 10 2 disk. (HI)/ of is [N;(H 0 hot that X (1984), quiescent et star , is radiation 1985). 40,000 45 45 45 accretion is , (quiescent size secondary, the Parameters particle assume The phase), 10 al. the from ]£ ] CI s- subdwarfrather star 312 Data in the It 5. 9 disk, 0 10 1 estimated 1991, values values Cygni I)/ ] em mass only AG may from , , 1 The 45 (This 1 with the K. secondary Lutz 2 relationships 10 relationships ) bound. phase may , and here X System disk Ora that and • 45 If, other lower be of boundary-layer phase), of and kL CI 10 a ] Work) et LT secondary be on , Tb temperature that that 9 is if This Ld scenario 8 are Cygni. al. the em, = is 1 a main-se­ the due Otherwise candidate • limits the = M is the different than (1987), the the proper­ Work). ~ source a I to are other are total 10 1 sub­ We, two ( ob­ the 211 the are as- cf. in -s 1993ApJS...84..201K tios. specific dates this tral nebula, because abundances. available equation LORES the UV (Kafatos where region's the tation the following electron cited ing tal served fatos, otic ionization tion tion tive nature nebulae. behavior prominent. e.g., abundances Dra regions. spatially sented cence linear gues tion higher surrounding larger 212 sumed The Assuming Recently, We The CIN images values nebular ionized AG and manner stars phases state from states L of in that lines, Michalitsianos, when next energy, during have a line dependence of density below - overall ion, these the here not spectral as temperature, In solid and Dra, not spherical coincident ionization In et ( 1 ) the in of ions; manner: 7-9 of stage 1979-1989 like all that fluxes step outburst, described © 1979-1989 bearing of size nebula, analyzed all al. Nussbaumer the order general. for with plotted d the all 0 the ne the outburst ionic 4. to argues outburst. and angle American tl.E, the UV = X C IN this linear regions possible were was 1980). the observable = DISCUSSION Z, L, abundance image the flux-flux effective 700 star. IV 10 we all 3 to symbiotic abundance nebular have depends abundances reinforces and the lines ions stages in and 12 of to with nA X versus has available, the ions have for however, find pc, dependence the Te, by em mind period During phenomenon assign & 10 period. which the distance Furthermore, and compared the ionization with N found rather LORES been EB-v C Hollis the et originate 10 Dyson strongest of whose photosphere for the plots followed v. IUE C fluxes. shape chemical IV, cm- al. on Astronomical determined the a of AND electron more star strong In and our IV the shine given = ratios ionic set outburst, The ( thus the the one common small through possible 1988) an argue 3 of general, 0.06 ( lines XA1548, lines SWP and & intermediate interpretation may 1986). calculated CONCLUSIONS has equal to dereddened of linear stages the realistic values The values would a covering ion in UV in, element. abundances UV for for Williams abundances procedure solar (Viotti variations the density, had we have Te for been hot shed are similar and primarily, where 24 this detailed Az, a emission lines. "stratification" the we to if dependence = emit For properties 1550 have line of size not emission acceptable other star symbiotics, present values, calculated L L 10 may some light object L assumed quiescent of all et the We WP 2 Society collisionally ne, The 4 have the are lines I fluxes L line ( spatial from (see to assumed KAFATOS, al. d K, the element similar that 1980) of ions from relative proceeded for I analysis 2 the be prevalent lower of high-ioniza­ lines high-ioniza­ , disk L time 1983 nA0• L and we flux, in individual expected in or WR Fig. in L in observing the all line Earth, in obtained were SIN is and elemen­ a applied the /g to and the includ­ regions similar for symbi­ ends all on to of evolu­ ), of F, in limits of not quies­ linear given • 8) spec­ solar A ionic each exci­ = and K.a­ pre­ far­ AG the the the ob­ the the Provided the not ex­ the ra­ ac­ all ar­ in d, in in as 1. is MEIER, a (Julian correspond absolute vember) the solid maxima dances two vember (see of abundances UV, at The unger's sent (Fig. 9 versus mum em; treme stages for 7.48 a limit them vary that size formed ions AG photoionized 10 13955 'ii 0 z z z > ~ 1! 'a ~ _g .. c c 0 given are FIG. & Again the which The spectra by 12 0.80 0.00 0.40 0.60 1.00 N line, for L Dra arrows the outburst Table Max em. ions MARTIN under by X strong 4000 estimates 9) (Kaler Date) 9.-Ionized v, two together. cases time the to of value (C we L_ r------,.,~----.-----.----. and line intensities line achieve C observation ( in and ··············- 10 and not 9.28 1980-1981, assuming (e.g., of the 1979) had unacceptable maxima NV to all __ NIV IV (U) with overlapped the found thecorresponding II). ( 12 for NASA 6). (Julian the 1985 shown the binary study of N m N generally and and the more of 1985 em; 19 ...... X AG nebulae same = events Lutz high-ionization For outburst ___. the extrema The l for 8 ephemeris We 4500 similar 10 normalized February-1986 ions JD fractions (bottom) 0 were 7) Dra. __ phase and and February by solar 12 than size L. in m, Date). example, of nebular [ et then date, was were 2438900 Astrophysics /····t maxima em; Julian 1985-1986 in N their each follow and the present outbursts, In 7.04 al. ~ events finally in minima L according _:____.__.>====----..J._-_---'-.J I v(top)isthe ionization the (maximum a signal-to-noise ofN not cosmic is general, for assigned general assigned .. 1987; binary .! Day 5000 factor Lines the for figure closely X ionization same region...... available, to of abundances those N v, + 10 in the (+2440000 and January). for dotted in the AG stages r··············-·······--··········j IV, 1986 N Friedjung in to 554E, 12 abundances, from the most outbursts. phase of 1980 and arithmetic represent IV, the group. Si Meinunger to Dra em; 0 the minima of apparent the dashed correlate potentials Therefore, -2 line. values and m, 5500 each IV, or January: the the (N outburst Data values ratios. for the ( DAYS) binary November of potentials same for Where to l 1980 and minimum) 0 and spectra between N The v) binary line, the the find ions of individual C 1988). III II, and ofthe the of the November-1981 We ( m, System arrows mean magnitude of He value lines N plotted 1979). available particular NIV(rniddle) with we phase and the shown are the the we spectrum were the brackets N 6000 UV low-ionization v, phases applied II, i\l present /~ are •• and the Julian We m, classified to \\'.• scale ionic likely C of normalized represent N 7.94 - of _____ The scale the against saturated during flux will broken, -----:-, group, 1981 and II the in most IV, the .... assumed grouped images. brackets ···· in Vol. 3.78 size binary case Figure X Mein­ in abun­ repre­ .... maxi­ Dates size occur a lower to Si SWP m N is both .i scale 6500 time /\ No­ 10 plot No­ the the the the the the ex­ IV, on L: or be 84 of X L 12 1993ApJS...84..201K instability panion, et cool in extended intense that tions. the warm heated ponentofabout N star, activity its Friedjung rate the the binary ( companied from of claim around occultations Roche model No.2, ejected of 1984). quiesence. However, thermonuclear triggering nuclear hot inner to ~10- phase. 1981 1987), Iijima The al. The AG v), the a Roche lobe. the upper presence mass star the from spherically star superposed ( outburst the regions 7 wind stellar and that 1984), Dra spectral for This hot overall model The lobe, 1993 by during than M of cool causing runaway the as is ( itself cool of 1987) chromosphere 0 K-type the atmosphere the ( of AG exposed, well part Kenyon component the This (as the 1988), physics probably © by yr- would massive the wind component but of that of the suggested of hot outbursts. in star. could of indicated orbital Dra, American outburst variations mild radiation as Mlirset 1 runaway of K both an symmetric the could found 10- an disk AG accretion which on if during event. giants. source Lutz observed from it star does indicate extended the of accretion complex on or & 7 large-amplitude be is hydrogen Maximum Maximum Maximum Maximum Maximum an Dra (white M produced comes the motion Orbital indicate a mass and/ alternatively, Phase probably et Webbink blackbody does the hot et peculiar 0 the the lijima that not accretion episodes by quiescent He (Viotti There from has yr- al. as and of of al. accretion region basis companion mass cool in that the UV having or favor Astronomical ( AG dwarf) concludes the the not 1 an (1991) photoionized phenomenology from THE 1987) , disk accretion transition other of ( the much the flashes. that by presence seems extended 1987) variations by the et giant extended Drain of accreted hot come accretion MAxiMA with the ( the (or disk continuum the present that al. 1984) inner been accumulation having phases. insufficient in relate process, ionic hot 2444400 2445000 2446100 2445500 2446600 K also that higher variations companion. Julian star thermonuclear disk) 1984 primary. EXTENDED Date to cool considers outburst rapidly and However, stars, that is close the rate has powered component, of wind be region AND report we atmosphere formed abundances interpret by the which hot analysis. a are ). star shell an UV region Lutz P are it an than no onto stellar temperature, are Moreover, the and Cygni emission to MINIMA is of Society is region ionized due higher of accretion model still More maybe indication the may caused a quite the absent overfilling being AG (Viotti observing itself the unseen et the the cool by Slovak probably at of mass Minimum Minimum Minimum Minimum by Minimum An to wind underlying the unknown, al. Orbital profiles likelihood that a Phase support mass-loss Dra. the VARIABILITY hot OF could runaway recently, which rates the periodic that thermo­ possible calcula­ respond portion present may intense formed lines (1987) by during loss AG Viotti 1980- et more com­ • com­ wind time. et disk, cool The and star of fills the the ac­ Provided DRACONIS an al. be al. its in be to of is a TABLE6 a 2446900 2446300 2445800 2444700 2445200 Julian Date would and complex instabilities Mlirset Assuming monuclear yr- rates bursts Hubble ( of outburst gues thermonuclear binarity should, orbit. outburst. or, km tion. with nism rial expected evidence mass velocities velocity star source (Table accretion - 7 clear AG UV wavelengths, observations w-s mainly CALCULATED 1986) 80 OF It Moreover, Also, First Even the 1 by alternatively, in s- lines km • optical Dra parameters(§ is are ~ against M Since runaway of loss Even Ejection white 1 AG slow is require clear (Table 5) the indicate 3 et which 0 of on Space because the in s profiles. ofthe ejection too phase accretion times which tied for over that The al. yr- than disk should occurs 1 all, the R* the DRACONIS ) this Quiescent Quiescent Active Quiescent Active runaways. if outburst. ( small wavelengths NASA dwarf FOR State should large that System Livio 1991) thermonuclear 1 at thermonuclear we the R* to it high absence can N v N the ~ Telescope) other 4). model a is is in system. and from binary outbursts that all is may THE suffices of Outflow still mass tied the present, the from required 0.03 of HIRES not be strange time ~ and entire not The rise near profiles wavelengths process 1986). we contemporaneous velocities the 3.4 be BINARY high hand, the Astrophysics O.Ql associated case can be accretion and to very find the would period accretion to present of ~for The the lack scale lack and the to derived time binarity. outward are contemporaneous a distinguish rates velocities when observations the over to coincidence ~ case, (ii) be (+2440000 that give (cf. in high say near extended PHAsE Chandrasekhar only of 3.5) -6500-7800 -6100-6500 -4900-6100 -4500-4900 -3800-4500 of runaway between needed Julian be runaways. (even in expected scale argues this hot (cf. the an in of high that extended fundamental an Livio the evidence process, we ( themselves with value the so rate only Viotti the mass yields accretion regions viable star. subdwarf One white accretion Kenyon Date of hot conclude in closely for either velocities hot UV for for days) between atmosphere of higher observations coverage outbursts Data N 1986). from of is transfer to star of would et R* of a M v some understanding dwarf present star. The possibly mechanism lines, periods ~200 of be of al. hot an are analysis AG is & = tied limit ~ outburst suppress hot contemporaneous observations is rate closely an degree System physical the that 1984). These 0.31 outburst We results present, (i) Webbink subdwarf. in not beating larger in 3.7 and and/ Dra at (see km accretion outflow ( to of in only are including the ~4.5 a X-rays, of due no would x expect ~. M argues that for thermonu­ the s- any tied (from Table or of accretion required. any model. the observed w- of concrete for ionizing ~ 1 data mecha­ V to the masses ioniza­ during yr) binary period V higher of radius of to mate­ 1984; 4.5 Livio giant esc 3 ~ ther­ If at have UV, out­ disk disk that that ~ 213 the the the hot 4 the ar­ an 40 an on all ~ X ), 1993ApJS...84..201K Janssen, Lutz, Cassatella, lijima, Kafatos, Kafatos, Kenyon, Kafatos, Hummer, Kaler,J.B. Livio, F1ower, Altamore, Anderson, Allen, for Kafatos, Huang, Mason Kenyon, Kaler, Dyson, Bohlin, Kenyon, Friedjung, M. 214 (NY: ed. otic 204 M. Ricardi, Sources, Press) Viotti, Workshop I. awarding M. Friedjung, J. M. Stars, C. J. T. M. J. C. C. C. R. D. Wiley) H., E. M., M., M., M., University, B., S. S. S. Friedjung is R. W. E., 1987, D. 0., C. A., C., A., ed. 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