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[WC], PG1159, Born Again stars: do we need an alternative scenario?

[WC], PG1159, Born Again stars: do we need an alternative scenario?. Orsola De Marco American Museum of Natural History. The bottom line . The FTP is needed to explain observed abundances, The 5 born-again stars are hiding something: why are the ejecta O- and Ne-rich?

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[WC], PG1159, Born Again stars: do we need an alternative scenario?

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  1. [WC], PG1159, Born Again stars:do we need an alternative scenario? Orsola De Marco American Museum of Natural History

  2. The bottom line • The FTP is needed to explain observed abundances, • The 5 born-again stars are hiding something: why are the ejecta O- and Ne-rich? • There is an FTP -> [WCE] -> PG1159 sequence. • [WCLs] are formed by FTP + something else (maybe a binary) and are “stalled”. • Most PN might need some kind of binary interaction. • Putting it all together - not yet. [WC] evolution alternatives

  3. H-deficient post-AGB star classes in this talk: • Any post-AGB stars with atmospheres composed of: C + He (+ O + none or little H) • Not the RCB stars, HdC, EHe stars… which are mostly made of He [WC] evolution alternatives

  4. BAs = V605 Aql BAs = Sakurai BAs = A30,A78 H-deficient post-AGB star classes on the “loopy” HR diagram [WCL] [WCE] WELS • The FTP abundance predictions match PG1159 non-DAs (DAs?) Bloecker 1995; but Detlef invented it [WC] evolution alternatives

  5. But there are big problems … • With the born again stars • With the [WCLs] [WC] evolution alternatives

  6. An issue with the Born-Again stars • C/O << 1 and high Ne for the knots of two BA PNe in contradiction with BA theory Wesson et al. (2003, 2007) 130’’ 1’’ Bond & Pollacco 2004 50’’ [WC] evolution alternatives

  7. BAs: ONeMg novae? Wesson et al. 2007 [WC] evolution alternatives

  8. Probably not, but… • There is no compelling evidence that the 5 known BAs are particularly massive. • Novae do not generate H-def WDs, FTPs do. • Need an FTP: but could a binary interaction interplay with the FTP? • However, C-O PG1159 star (Rauch) and CK Vul (Shara) Demonstrative cartoon pilfered from the web [WC] evolution alternatives

  9. BAs: a couple more problems • The frequency: • Why are there only 5 known H-deficient PNe?(Why don’t more WCPN show H-deficient ejecta?) • The morphology: • A30 has collimated polar knots suggesting an accretion disk. (Kimeswenger, Harrington) • All 5 BAs have spherical/elliptical PNe. This could point to single star evolution. However, known 3 (?) post-CE binaries are also found in spherical/elliptical PNe. [WC] evolution alternatives

  10. [WCLs]: Their unique characteristics (part I) Waters et al. 1998 (Nature!) • Effectively all WCLPN have “dual” dust chemistry: PAH (carbon-based) and crystalline silicates (oxygen based) rich dust. • WCEPN are rarely associated with the dual dust (one case). • No H-rich CSPN has the dual dust chemistry (though some pAGBs do - see later). (Cohen 2001) [WC] evolution alternatives

  11. [WCLs]: The unique characteristics (part II)(Zijlstra 2001) • WCLPN have unique IRAS colors: appropriate for stars hotter than pAGBs and cooler than [WCE], but not shared by H-rich CSPN [WC] evolution alternatives

  12. [WCLs]: The unique characteristics (part III) (Zijlstra 2001) • post-AGB stars evolve fast towards the hot part of the HRD, then slow down. • You expect few stars in the cool domain and many more in the hotter domain. PG1159 <- [WCE] <- [WCL] L Teff [WC] evolution alternatives

  13. [WCLs]: The unique characteristics (part III) (Zijlstra 2001) • There are too many [WCLs]: • There is a gap between [WCL] and [WCE]. • Low mass envelope + mass-loss => very short timescales. • The # and expected frequency of [WCL] would imply longer timescales. PG1159 <- [WCE] <- [WCL] L Teff [WC] evolution alternatives

  14. PAH outflow few Ro Silicate dust outflow Only a few x 1000 yrs ~2000 AU Explain dual dust presence in [WCL] Rare overall Why crystalline silicates It should happen to H-rich CSs young PN few 1000 - few 10,000 AU The recent AGB departure scenario (Cohen et al. 1999; Waters et al. 1998) L FTP [WCL] Me << C/O>1 & PAHs form TPs start O-rich dust forms Teff [WC] evolution alternatives

  15. L FTP [WCL] PAH outflow Me << C/O>1 & PAHs form few Ro Silicate dust in disk TPs start O-rich disk forms (long lived, crystalline silicates form) Explains the crystalline silicates No fine tuning Teff ~2000 AU No dual dust in [WCE] Who makes the disk? It should happen to H-rich CSs. young PN few 1000 - few 10,000 AU The disk storage scenario (Cohen et al. 1999; Waters et al. 1998) [WC] evolution alternatives

  16. Make PAHs in O-rich flows Could explain SwSt1 (WC10 w/ O-rich PN) It should happen to H-rich CSs [WCE] could also have PAHs It’s not the chemistry!(extra slide for Falk) [WCL]’s UV radiation: CO is disassociated making C available; PAHs L FTP Me <<; C/O < 1 TPs start O-rich outflow Teff [WC] evolution alternatives

  17. Need for a causal & exclusive connection • [WCL] associated with dual dust • No H-rich CS associated with dual dust • Solution: dual dust H-deficiency or, H-deficiency &dual dust something [WC] evolution alternatives

  18. [WCL] causes PAHs PAH strength correlates with C/O (PN) PAH form in C-rich AGB stars (H-rich CSs can have dual dust) Who makes the disk? H-deficiency causes the dual dust? [WCL] wind is C-rich; mixes with PN makes PAHs L FTP Me <<; C/O > 1 or < 1 TPs start O-rich disk forms (long lived, crystalline silicates form) Teff [WC] evolution alternatives

  19. A common envelope interaction Density greyscale Orbital Plane (~top view) Density greyscale Perpendicular Plane (~side view) De Marco et al. 2003 1Mo topAGB star R=3AU 0.1Mo MS star

  20. L CE merger: in-spiral + destruction + disk sheer mixing: O -> C changeMe <<: AGB departure… TPs start The event causes dual-dust and [WCL] O-rich disk forms by companion action A merger would not make Me << How do we get the H-deficiency? Teff An AGB merger scenario for [WCs] - no FTP (De Marco & Soker 2002) … and makes the star H-def! post-CE: [WCL] [WC] evolution alternatives

  21. L CE: Me << C/O>1 & PAHs form TPs start The event causes [WCL] O-rich disk forms by companion action No FTP from this mechanism (?) Event does not cause the PAHs Teff A multiple CE + merger scenario for [WCs]? post-CE binary(a < few R*) Macc >> primary expandsnew CE [WCL] Expansion + Merger + FTP [WC] evolution alternatives

  22. Summary of the flawed scenarios • Recent departure (should see dual dust H-rich CSs) • Disk storage (same) • H-deficiency causes the PAHs (PAH strength set at top of AGB) • UV dissociates CO making PAHs (should see dual dust around H-rich CSs) • Small companion merger causes PAHs and H-deficiency (cannot make H-deficiency without FTP) • Any variations on the theme above (cannot trigger FTP from binary interaction; should see dual dust arounf H-rich CSs). [WC] evolution alternatives

  23. PG1159 <- [WCE] <- [WCL] L Teff Oh… and of course we need to stall the march of the [WCLs] [WC] evolution alternatives

  24. The wider PN context • Axisymmetric PNe need an angular momentum source - companion or accretion from a pre-formed disk. (Nordhaus et al. 2006; Soker 2006) • Hypothesis: a (close) binary is needed in the the majority of all PNe. • [WC] CSs would have to slot in this wider context. • Binary fraction (P<3days) >13%, that is all we know. Abell 39 WYIN 3.5 m telescope [OIII] (G. Jacoby) Hubble 5 HST [OII]/[NII]/[OIII] (Balik, Ike, Mellema) NGC6826 HST [NII]/[OIII]/V (Balick et al.) [WC] evolution alternatives

  25. PlaNBcollaboration [WC] evolution alternatives

  26. We have partial matches • Subsets of all the “facts” fit together within certain scenarios …… but not all “facts” hang together to give us the overall picture. Jody Foster (Ellie Harroway) in the movie Contact, failing to join together the many pages of instructions. [WC] evolution alternatives

  27. We are not there yet • What lateral step do we have to take to fit all the facts together? Ellie eventually figures out that the pages have to be joined in 3D. [WC] evolution alternatives

  28. Evolution of 1-8 Mo single stars: from the main sequence to white dwarf sdOB stars = Iben 1985 [WC] evolution alternatives

  29. CE outcome is a sensitive function of the exact evolutionary status of the primary Merger Bottom-AGB Top-AGB Binary Orbital plane Perpendicular plane [WC] evolution alternatives

  30. M2-9; Balik; HST OH321.8+4.2; Bujarrabal; HST PKS285-02; Sahai; HST Extremely bipolar to point-symmetric … He2-401; Sahai; HST [WC] evolution alternatives

  31. Bipolar structure within spherical halos NGC6543; Corradi, Goncalves; NOT [WC] evolution alternatives

  32. 3 common envelope simulations 1 Main Sequence Mass = 1.5 Mo Bottom of the AGBTop of the AGB [WC] evolution alternatives

  33. Population synthesis:Comparison with mass dist’ns • Predict: MCSPN > 0.55 M • Reasonable match to observations. • What about MCSPN >~ 0.7 M? [WC] evolution alternatives

  34. Population synthesis:fraction of WD that go through a PN phase predictedCSPN mass dist’n 77% of post-AGB starshave M > 0.55 M andmake a PN. WD mass dist’nLiebert et al. 2005 Post-AGB no PN post-AGByes PN: 82% post-RGB WD [WC] evolution alternatives

  35. 2. The Mass Issue • The mean CS mass is too high (0.6-0.65Mo). • CSPN mass distribution is very narrow and peaks at higher mass. Gesiki & Zijlstra 2006 • Assuming that the PN kinematic age = the evolutionary age ofthe CS. [WC] evolution alternatives

  36. L Me << C/O>1 & PAHs form TPs start O-rich disk forms by companion action Teff Other post-CE CSPN. (De Marco & Soker 2002 - revised) Look out for the “SOMEHOW” FTP CE No merger, no [WCL] Yes dual dust. Prediction some post-CE CSPNe have dual dust PAH formation in an O-rich WCLPN by mass-loss (SwSt1) [WC] evolution alternatives

  37. What do [WCL]s evolve into? [WCE] w/ double dust [WCL] L PG1159 Some PG1159 fast rotating [WCE] no double dust PG1159 non-DAs Teff [WC] evolution alternatives

  38. What about [WCEs] WELS and PG1159s? CPD-568032 has a disk PG1159 stars are fast rotators CE+ Merger induces FTP: CS becomes [WCL] post-CE binary (P<<) Macc >> expansion L CE: Me << PAH formation in an O-rich WCLPN by mass-loss (SwSt1) C/O>1 & PAHs form TPs start O-rich disk forms by companion action Teff [WC] evolution alternatives

  39. pAGB binaries with double dust and disks • Double dust common in pAGBs with disks. • Disks long lived (high level of christallinity). • All pAGBs with disks are binaries. • Periods between 200 and 1500 days. • Some are post-CE some not. • Can [WR] CSPN be the descendant of these stars? • If dual dust pAGBs do NOT become [WC]s, then they become H-rich CSPN, but where does the dual dust go? Or maybe they never become CS? • Is there dust around WDs? Where does the O-rich disk go? “Debris” disk around the helix? [WC] evolution alternatives

  40. The mass determination method • From Teff and tkin determine stellar mass that reaches Teff in tkin. kin = 12,000 yr L Teff = 40,000 K [WC] evolution alternatives

  41. This method should not work for FTP stars • Undetected TP loop will make PN relatively large for the Teff - mass is underestimated by a variable amounts - spread the mass distribution, not make it peakier!! kin = 12,000 yr kin = 23,000 yr kin = 30,000 yr L L L Teff = 40,000 K Teff = 40,000 K Teff = 40,000 K [WC] evolution alternatives

  42. In addition, the [WCLs]… • A common envelope would by-pass the transition time, overestimating the mass. kin = 12,000 yr kin = 1,000 yr CE happens here CS emerges at higher temperature after ~10 yr Teff = 40,000 K Teff = 40,000 K [WC] evolution alternatives

  43. Masses: conclusions • It makes sense the the [WCL] masses determined by the method are all over the place. • It makes no sense that the [WCE] masse are concentrated into one bin. • Once again the [WCLs] seems different from the [WCEs] [WC] evolution alternatives

  44. The masses of [WC]s (Gesiki & Zijlstra 2006) • Mean [WC] mass same as for Hrich • Mass dist’n is peakier for [WCEs] • [WCLs] have a flat mass dist’n [WC] evolution alternatives

  45. L CE: Me << C/O>1 & PAHs form TPs start O-rich disk forms by companion action Teff Post-AGBs with dual dust. (van Winckel 2003) post-CE binary (a > few tens R*) No merger, no [WCL] Yes dual dust. [WC] evolution alternatives

  46. 1. High H-def CS rates in “anomalous” environments • In the Sagittarius Dwarf Spheroidal galaxy: 3 of 4 CSs have [WC] class (Zijlstra et al. 2006). • In the bulge: more [WC] in general and more [WC11] in particular. (Gorny et al. 2004) [WC] evolution alternatives

  47. The Final Thermal Pulse (FTP) scenario (Werner & Herwig 2006) • Low envelope mass • inter-shell abundances • random • A few issues Bloecker 1995 [WC] evolution alternatives

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