PoS(GOLDEN 2017)058 https://pos.sissa.it/ CI Aquilae, the only known al that the accretion rate of T l abundances in the el recorded by the IUE following e dwarf in the prototypical dwarf tal period recurrent novae (RNe) HST) far ultraviolet spectroscopy ve yet reached its (new) quiescent ds less than a day. The last two HST IV onomy, Johns Hopkins University, Baltimore, MD [email protected] † , ive Commons onal License (CC BY-NC-ND 4.0). and Patrick Godon ∗ [email protected] Speaker. Visiting in the Henry A. Rowland Department of Physics & Astr recurrent novae with main sequence donors andCOS orbital spectra perio we obtained inPyx October, has declined 2016 by and 20% below June, itsthe quiescent 2016, 1966 continuum reve flux outburst, lev an indicationstate. that Recent the HST system COS might Spectroscopy of not the ha cooling of the whit with the Cosmic Object SpectrographT (COS), Pyxidis, of IM the Norma short (the orbi first ever FUV spectrum of this RN) and U Geminorum is also discussed with a focus on the chemica We report on the latest results from ( photosphere. ∗ † Copyright owned by the author(s) under the terms of the Creat c Edward M. Sion The Hot Components in the RecurrentPyxidis, Novae IM T Norma, CI Aquilae andU in Geminorum the Dwarf Nova Astrophysics & Planetary Science Villanova University Villanova, PA 19085, USA E-mail: The Golden Age of Cataclysmic Variables and Related Objects 11-16 September, 2017 Palermo, Italy Attribution-NonCommercial-NoDerivatives 4.0 Internati 21218, USA PoS(GOLDEN 2017)058 /yr ⊙ M 6 − /yr). However, Edward M. Sion ⊙ M 6 − ort orbital periods and ectroscopy. In Table 1, we ed more than one recorded 6 outburst. T Pyx had already led a further 20% drop in the volved (subgiant or red giant) tance of 4.8 kpc, [4] we found ossibilities for a solution to the (1300) emission line and strong he Oct 2016 but still well below be hidden. Two possibilities have . These two factors are the critical recurrence time between outbursts ent reviews on the properties and ekhar mass limit and explode as a t-Xray/EUV source is not detected. iminary study assuming a distance III level of the 2013 HST observations nce must be a source of strong soft e 1980’s and 1990’s. To our surprise, y high accretion rate of 10 f the order of 10 n the following three subsections we EUV radiation which is at so great a x and optical and X-ray studies of IM tems from the literature, in some cases + Si I Outbursts 1 orb P /yr [17]. Such a large mass accretion rate implies that ⊙ M 8 − 10 The T Pyx Subclass of Recurrent Novae = ˙ M Table 1: Name max min (d) (d) () T Pyx 6.4 15.5 62 0.076 1890,1902, 1920,1944, 1966,2011 CI Aql 9.0 16.7 32 0.62 1917,1941, 2000 System V V t3 IM Nor 8.5 18.3 80 0.102 1920,2002 (1238, 1242) absorption lines appeared for the first time 1 kpc we obtained V ∼ The first FUV spectra taken with IUE were 14 after the 196 The recurrent novae (RNe) are a subset of CVs that have suffer However, a small subclass of RNe (T Pyx, IM Nor, CI Aql) have sh From our model continuum slope fitting, and the light echo dis the inner disk/boundary layer/white dwarfX-rays and is EUV very emission. hot However, this andThe expected he very question hot then sof becomes how suchemerged; a source (1) of The emission hot could source either emits intense soft X-ray/ reached deep quiescence after its 2011reached the outburst continuum when flux the level of flux theour IUE Oct spectra taken 2015 in and th JuneFUV 2016 COS flux spectra (Fig.1), of with T thethe Pyx June IUE (Cycle 2016 23) quiescence flux revea flux being level. slightly above Remarkably, t a strong O 1.1 T Pyxidis (Nova Pyxidis 1890) Hot Components 1. The Short T Pyx Subclass of Recurrent Novae outburst on recurrence timescalesbasic of parameters a of RNe year can to berequire a found both in century. a [1, massive 2, WD Rec 16]. andingredients Their a needed short high for accretion an rate [22, accretingType 9, Ia WD 25] to (SN reach Ia), the whichlongstanding is Chandras why SN RNe Ia are progenitor among problem the [13]. best p main sequence (MS) donors starsdonor companions like and CVs. long orbital Alldescribe periods other the (days RNe latest to have HST years). e far I UltravioletNor spectroscopy and of CI Aql. T Py Both IMprovide Nor the and physical CI and Aql orbital have parameterswith had of large no uncertainties. the previous FUV three sp sys assumes the light echo distanceof of only 4.8 kpc [21], while in prel the accretion rate depends strongly on the distance: the ver that the quiescent mass accretion rate in T Pyx is very high (o broad N PoS(GOLDEN 2017)058 Edward M. Sion tude-Rate of Decline ectroscopically. In the lor for clarity. The 2012 & -ray source 6 months after the aring of the accretion disk outer e white dwarf mass is increasing II class, but one month later, the s based upon the assumed redden- well as standard disk models. Dec 2012 Jul 2013 Oct 2015 Jun 2016 ant into quiescence. One possible e variation of only about 5%, indicating ity of a GAIA distance, an upcoming erstellar medium, or (2) the hot inner ms to show a slight increase in flux level. 996) IUE SWP spectra (not shown here), iods between 2 hr and 3 hr where very However, the 2015 spectrum showed a further 1500 1600 2 to be 2.46h which places IM Nor in the middle of the CV orb P The last four HST FUV spectra of T Pyx have been displayed in co 1200 1300 1400 The 2002 outburst of the RN IM Nor was followed visually and sp At this time, we are unable to state unequivocally whether th The distance to IM Nor was determined using the Maximum Magni 0 1e-14 2e-14 3e-14 4e-14 beginning of the outburst,spectrum the changed nova to belonged the to He/N2002 Williams’ outburst class. Fe [12]. It [24] was found detected its as a hard X or decreasing with time. ThisHubble Cycle issue 25 must COS await observation the ofing availabil T E(B-V) Pyx, of and the further system, analysi GAIA parallax, and non-standard as 1.2 IM Norma (Nova Nor 1920) 2013 spectra have the samewhich continuum was interpreted flux as level having asdrop at the in last (1980-1 the reached flux quiescence. levelBetween by 1980 about and 20%, 1996 while the the IUEthat 2016 spectra the of spectrum present T see change Pyx is showed more an than averag a fluctuation. distance (4.8 kpc), that itdisk/BL/WD is soft completely X-ray/EUV emission absorbed is by hiddenedges the by when int viewed the at upward a fl high system inclination. Figure 1: Hot Components period gap, an interval infew the CVs distribution are of found. CV orbital per (MMRD) relation [16]. Its remained fairly const PoS(GOLDEN 2017)058 , ⊙ R 06 24 and . . 0 0 ± ± (1548, 1550) 07 . 35 IV . emission, strong Edward M. Sion 2 α = q splayed in Fig.2. No 1700 1800 (1300) along with some complex on a reddened er the 2000 outburst [7]. and the mass of the donor III g strong Ly III ⊙ | elengths as expected for a hot M He II + Si -N 14 . I 0 4.8 h, with a K-M evolved or MS r has a persistent supersoft X-ray esembled that of T Pyx type RNe. III tum loss mechanisms cannot drive ass accretion rate [10, 16]. That is, ± which implies that its donor is a MS re. (1640). The analysis of this spectrum nt from classical nova systems. The urrence time scale. high mass ratio of 00 II | and O . he low S/N of the spectrum but several C IV α o , and the C 1500 1600 II (1238, 1242), both components of the resonance 3 V Wavelength (A) IM Nor - HST/COS Spectrum IM Nor - HST/COS Spectrum | . They estimate the radius of the secondary to be 2 O V ⊙ M (1238, 1242), both components of the resonance doublet C Si III 19 . | V | 0 ± O I 32 . | N V o | H I (1548, 1550) and the recombination line at He 1200 1300 1400 | IV (1300) and weak N (1640). Note that the FUV continuum rises toward shorter wav An HST COS spectrum of IM Nor (Flux versus wavelength) showin C III III II CI Aql was detected as a soft X-ray source, 14 and 16 months aft [8] showed that its spectral evolution during the outburst r The first ever FUV spectrum of IM Nor (an HST COS spectrum) is di + Si I 6e-14 4e-14 2e-14 F (erg/s/cm**2/A) implying that it is a slightly evolved early A-type . The spectrum [2]. [8] finds that itsstar. distance does not exceed 1 kpc From radial velocities, [14] find the mass of the WD to be 1 secondary star to be 2 source. 1.3 CI Aquilae (Nova Aql 1917) [11] found that CI Aqldonor shows star. eclipses on an Its orbitalspectrum optical period shows quiescence of weak spectrum 1 emission is lines very due differe to He and He Figure 2: Hot Components explanation for this near constancy is that, like T Pyx, IM No source which heats its companion starIM so Nor as has to a drive short thethe orbital high accretion period, m at but the ordinary high angular rate momen required to power the shortabsorption rec features are clearly detectable, in part due to t emission features are seen, the strongest of which are Ly awaits a GAIA parallax distance and will be reported elsewhe O relatively weak emission features including N doublet C PoS(GOLDEN 2017)058 Edward M. Sion RS Ophiuchi (1400Å) that are IV , during the 2002 outburst er systems, reveal their un- Villanova University dt / owland Department of Physics inistration (NASA) under grant r, the Al abundance is 20 times eries obtained 56 days after the possible CNO enrichment of the dP 0 times solar. While it cannot be he N/C abundance ratio is anoma- lode as a SNIa, possibly within, 10 1112Å) and Si USA, for his kind hospitality. This C UMa and SW UMa. All of these nfirms the high N/C ratio observed ft x-ray source, and will eventually & M. J. Darnley eds., ∼ U Gem. ial veiling the WD rather than in the g white dwarf in U Gem as a function ered nuclides remains a mystery, it is ( occurs on a thermal time-scale. [15] /COS spectra was intended to look for the photosphere of a CV white dwarf. makes it possible to carry out detailed U Gem, VW Hyi and WZ Sge(see ref- high temperatures associated with ex- spheric overabundances are associated and in some cases elevated Phosphorus. rbon and sulfur, iron is only marginally ccretion-diffusion equilibrium and other III 4 ASPCS 401, San Francisco, p.31 ), Silicon is sub-solar except for the Si ⊙ ] Fe [ (2006) & the Recurrent Nova Phenomenon PG is pleased to thank William (Bill) P. Blair in the Henry A. R While the full analysis of the spectra remains in progress, t The prototypical dwarf nova U Gem, along with a handful of oth Recently, [6] reported the results of a study of the accretin [1] G.C. Anupama, 2008, in: A. Evans, M. F. Bode, T. J. O’Brien solar. In Fig.3, wereturn display to the quiescence following final a COS wide spectrum dwarf nova of outburst the of time s Acknowledgments & Astronomy at the Johns Hopkinswork University, Baltimore, was MD, supported by thenumber National NNX17AF36G, Aeronautics HST grants and GO-14641 Space and Adm GO-14111, all to References suggest that CI Aql mayexplode be as evolving an into SN Ia. a persistent ModelsMyr also superso [14]. suggest it Moreover, may [23] ultimately found exp that the rate of period change Hot Components the high secondary-star mass implies that the mass transfer previously in the FUV spectra ofaccreted U material Gem on in the quiescence, WD a surface. sign of lously high as found bysolar [19], and the the N likely abundance detectionruled is of out 20 Argon that x with the times absorption an sola WD lines abundance itself, might of if be confirmed, 2 forming this is inThe the mater spectra first detection also of exhibit Argon solar in tosupra-solar sub-solar (2 abundancesof ca processes in the CV white dwarf photosphere. Our analysis co indicates that the WD is growing in mass. 2. The Accreting White Dwarf in the Dwarf Nova U Geminorum derlying white dwarf photospheres during quiescence.chemical abundance This analyses like those reported byerences [20] therein), for and [3] for theobject dwarf have suprasolar nova Al systems abundances BW in Scl, their B While photospheres the origin of these suprasolarclear abundances of that odd-numb to synthesize theseplosive heavy CNO elements burning [18]. requires Thus, very itwith is the likely accreting that white these dwarf. photo of time since a single dwarf nova outburst.any variations This of series the of metal HST abundances that could relate to a PoS(GOLDEN 2017)058 Edward M. Sion outburst, modeled with a , Proceedings of the The Physics of Cataclysmic eds., 81, p. 193-194 146 e 4 sub-exposures obtained in one (HST) pJ,submitted s, C. Woodward, P. Kuin, K. 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