The Place of Recurrent Novae among the Symbiotic Stars
Joanna Mikołajewska Copernicus Astronomical Center Warsaw, Poland Symbiotic stars
S(stellar) normal giant 80% -7 Mg~10 Msun/yr Porb ~ 1-15 yr
•Accreting white dwarf majority
•Neutron star D(dusty) •Disk-accreting MS star? Mira + dust evelope •Black hole? 20% -5 a few Mg~10 Msun/yr Porb > 50 yr
RS Oph, T CrB, V3890 Sgr & V745 Sco are S-type RNe Points to be addressed
• Orbital parameters • The hot component & its activity • The cool giant & mass transfer Orbital parameters
• 70 SyS – known orbital periods (Belczyński et al. 2000, Mikołajewska 2003, 2004; Gromadzki et al. 2007)
• 32 SyS – known spectroscopic orbits for the cool giant (Mikołajewska 2003; Hinkle et al. 2006 – V2116 Oph; Brandi et al. 2006 - Hen3- 1761) T CrB: 227.6d RS Oph: 453.6d • 19 SyS – mass ratios (Mikołajewska 2003; 2007)
In both symbiotic RNe:
• Mg • Mh~1.1-1.4 Msun -the highest among SyS Spectroscopic orbits The hot component Quiescence: AG Dra •Overlap with central stars of PNe •TNR-powered white dwarfs •Stable /quasi-stable H-shell burning of the accreted matter or very slow TNR on low mass wd’s •Galactic and MC SyS overlap in HR diagram; MC systems are among the hottest and brighest systems However: Far UV SEDs for RW Hya, SY Mus and EG And indicate much lower T than emission lines (Sion et al. 2002, 2004) The hot component Iben & Tutukov (1996): accreting cold WDs Paczyński-Uus relation for AGB stars with CO cores •HCs cluster around the M-L relations for stars leaving the AGB with a CO core and the RG with a He core Hot He cores Iben & Tutukov 1996 •Symbiotic WDs could still be hot at the onset of the mass transfer from the cool giant The hot component Outbursts: •Symbiotic novae (AG Peg, RX Pup + 6); both S- and D-type •Stable (RW Hya, SY Mus) – -8 must accrete ~10 Msun/yr or extremely slow symbiotic novae: both S- and D-type majority? •Multiple outbursts Z And- type: only S-type how many? SyRNe: activity between outbursts Anupama & Mikołajewska (1999, and ref. therein): RS Oph, T CrB, V3890 Sgr & V745 Sco •Variable A-F shell source with LUV/opt~50-500 Lsun •Emission line spectrum: T>~50000 K and LEUV~LUV/opt but HeII and other high-ionization lines rarely observed •Flickering in RS Oph & T CrB correlated with the activity Mikołajewska et al. (1998): RX Pup -the same post-nova-outburst behaviour as in RS Oph & T CrB as well as the accretion-powered symbiotic CH Cyg -7 LEUV/opt ~100-500 Lsun consistent with unstable accretion at ~10 Msun/yr whereas LX indicates 1-2 orders of mag lower Mdot RSOph SyRNe: activity between outbursts Gromadzki et al. (2007, poster): Z And-type outburst activity between the nova eruptions in RS Oph RX Pup Z And What powers the multiple outburst activity? •TNR instability on high-mass (>1Msun) WD (Paczyński & Rudak 1980)? Problem: •Accretion disc instability on accreting MS star (Duschl 1988, JMik & Kenyon 1992)? Problem: only a few SyS may host an MS star •Combination-nova scenario: accretion disc instability on more or less stably burning WD (JMik 2001; 2002; Sokolski et al. 2005) The link between the SyRNe & Z And-type symbiotics • Both the activity of Z And-type SyS and the high & low states of SyRNe due to unstable disc-accretion onto WD • The WDs in Z And-type SyS burn the accreted hydrogen more or less stably wheras in SyRNe they don’t The cool giant •S-types: Sp types between M3 and M6, with a peak at M5 •D-types: peaks at M6 and M7 •The frequency of Miras higher among symbiotic giants Muerset & Schmid (1999) Yellow SyS: S-types •S: K III (e.g.AG Dra) •D’ G III & warm dust M giants in the (e.g. HD 330036) Hipparcos Cat. D-types RS Oph T CrB V3890 Sqr V745 Sco Symbiotic Miras •Longer pulsation periods •Optically thick dust envelopes Single Symbiotic •Higher mass loss rates, -6 -5 10 -10 Msun/yr, as compared to -7 average field LPVs, 10 Msun/yr •Dust obscuration in RX Pup and other symbiotic Miras can be related to intensive and variable mass loss The cool giant Most contain SRVs & thus may have mass loss rates -7 ~a few 10 Msun/yr (Gromadzki et al. 2006) The cool giant Large radius & high mass loss from the red giant are the key parameters for triggering the symbiotic phenomenon Red giant radii & distance scale 48 SyS – vrot,g sin i (Fekel et al. 2003; Zamanov et al. 2006; Hinkle et al. 2007) 31 SyS – also Porb Are the giants synchronized? Yes if Porb < 1000d Red giant radii & distance scale Generally the radii derived from vsini agree with the radii predicted by Sp type Rg~0.4-0.5 RRL but in some SyS they are larger although consistent with Rg~RRL H-R Diagram for cool giants Both galactic and MC symbiotics are low- mass systems Mg <2-3 Msun AGB giants in MC symbiotics and yellow galactic systems with P>900 days T CrB - normal RGB RS Oph – metal-poor AGB? What we know about chemical abundances of symbiotic stars? UV emission line analysis of 24 SyS (Nussbaumer et al. 1988): relative CNO ratios place SyS among red giants. Photospheric abundances: •AG Dra, BD-21 3873 & He2-467, yellow SYS, with K giants: metal poor with [Fe/H]<-1 & s-process overabundant (Smith et al. 1996, 1997; Pereira et al. 1998) •HD 330036, AS 201 & StHA 190, D’ systems with G giants & warm dust: high vgsini, [Fe/H]~0 & s-process overabundant (Smith et al. 2001; Pereira et al. 2005) • S-types with M giants: CH Cyg & V2116 Oph ~ solar abundaces; no evidence for s-process overabundances in red SyS... (Schmidt et al. 2006, Hinkle et al. 2006) Carbon abundance Single M giants Symbiotic giants Comparison of symbiotic stars (black) with single field M giants (magenta) from Schmidt & Mik 2003 RS Oph: [C/H]~ -3 /-4 (!!!); 12C/13C=10 (Scott et al. 1994) Metal-poor field halo giants: [C/H]~ -3, 12C/13C=10 & [Fe/H] ~ -2 (Keller et al. 2001) Consistent with with the position of RS Oph in H-R diagram & d~3 kpc Mass transfer in symbiotics 3D HD models: the cool giant wind must be focused towards the orbital plane (Mastrodemos & Morris 1998, 1999; Gawryszczak et al. 2002, 2003): In agreement with observations: • resolved nebulae in D-types (e.g. Corradi 2003) • spectroscopic evidence for jets & bipolar outflows in active S-types (e.g. Tomov 2003) Mass transfer in S-type symbiotics: via stellar wind? YES (Nussbaumer & Co), because: Sp types, vsini indicate Rg ~0.4-0.5 RRL no evidence for ellipsoidal variability, or Roche lobe owerflow? YES in multiple outburst systems (JMik et al. 2001; 2002, etc...) need red/near-IR photometry at quiescence to see the ellipsoidal variability Multiple outburst symbiotics CI Cyg: quiescent LC (Mik 2001) sinusoidal but with Porb in U & Porb/2 in VRI... AR Pav • A/F continuum most of time • Secondary P, also visible in JHK ... Z And q=Mg/Mh=3 … and even my best examples of the stable SyS!!! JHK(L) light curves • Ellipsoidal LC’s in AR Pav & Z And (active) but also in stable SyS RW Hya & SY Mus • No ellipsoidal changes in the classical symbiotic nova AG Peg • Secondary P, eclipses & ellipsoidal variability in high-eccentricity BX Mon T CrB Roche lobe filling giant q=Mg/Mh~0.6 i~60 Belczynski & Mikołajewska 1998 RS Oph Poster by Gromadzki et al.: •Primary minimum at the time of the spectroscopic conjunction with the red giant is in front. •Secondary minumum veiled by a moving bump? but If synchroneus rotation, vsini implies RL-filling giant AR Pav: A moving bump veils the secondary minimum in the visual LC… Ellipsoidal variability in SyS: • Absent in symbiotic novae (AG Peg) • Present in all (i>60; LC available) multiple outburst (Z And-type) SyS at quiescence (VRI) and activity (near-IR) • Present (at least in some) in steady SyS (near-IR) • Present in T CrB; need near-IR for RS Oph • All 12 SyS with ellipsoidal variability have d Porb <1000 and circular (e~0) orbits except BX Mon The RG radius – vsini problem What about the radius/v sin i ? • Asynchronous rotation? unlikely because of circular orbits • RL shinkage (up to 2-3 times!) expected in luminous stars with strong winds if some force drives the mass loss & almost compensates the gravity (e.g. Schuerman 1972) -7 very promising in Sys with strong (10 Msun/yr) and nearly constant speed winds A-F shell M giant Hot comp In AX Per, AR Pav & other active SyS associated with the hot comp (Mik & Kenyon 1992; Quiroga et al. 2002; Brandi et al. 2005; 2007) Departures from the expected circular orbit correlated with activity & due to stream res Hot comp In RS Oph – confusing (poster by Brandi et al.) Significant contribution from the stream? M giant Note the L1 point on the opposite side of CM as compared with the other SyS Main points: • Symbiotic RNe, RS Oph & T CrB, and V2116 Oph/GX1+4 are the only SyS with the cool giant being the less massive component, with mass < 1 Msun in all cases. The WDs in the SyRNe are the most massive, with M~1.1-1.4 Msun sufficient for them to become SNIa. • Tidally distorted red giants and RF owerflow are present in T CrB & RS Oph. RLOF can be quite common in S-type SyS • Both the activity of Z And-type SyS and the high & low states of SyRNe are due to unstable disc-accretion onto WD. However the WDs in Z And-type SyS burn the accreted hydrogen more or less stably wheras in SyRNe they don’t • Far UV SEDs inconsistent with em line fluxes in stable SyS may indicate the presence of accretion dics