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

H-Deficient Stars 2007[WC] evolution alternativesPage 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.

H-Deficient Stars 2007[WC] evolution alternativesPage 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

H-Deficient Stars 2007[WC] evolution alternativesPage 4 H-deficient post-AGB star classes on the “loopy” HR diagram [WCL] [WCE] PG1159 non-DAs (DAs?) BAs = Sakurai BAs = V605 Aql BAs = A30,A78 WELS Bloecker 1995; but Detlef invented it The FTP abundance predictions match

H-Deficient Stars 2007[WC] evolution alternativesPage 5 But there are big problems … 1.With the born again stars 2.With the [WCLs]

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

H-Deficient Stars 2007[WC] evolution alternativesPage 7 BAs: ONeMg novae? Wesson et al. 2007

H-Deficient Stars 2007[WC] evolution alternativesPage 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? (Rauch)(Shara)However, C-O PG1159 star (Rauch) and CK Vul (Shara) Demonstrative cartoon pilfered from the web

H-Deficient Stars 2007[WC] evolution alternativesPage 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: (Kimeswenger, Harrington) 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.

H-Deficient Stars 2007[WC] evolution alternativesPage 10 [WCLs]: Their unique characteristics (part I) 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). (Cohen 2001)No H-rich CSPN has the dual dust chemistry (though some pAGBs do - see later). (Cohen 2001) Waters et al (Nature!)

H-Deficient Stars 2007[WC] evolution alternativesPage 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

H-Deficient Stars 2007[WC] evolution alternativesPage 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 T eff

H-Deficient Stars 2007[WC] evolution alternativesPage 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 T eff

H-Deficient Stars 2007[WC] evolution alternativesPage 14 Silicate dust outflow PAH outflow young PN few few 10,000 AU few Ro ~2000 AU The recent AGB departure scenario (Cohen et al. 1999; Waters et al. 1998) TPs start C/O>1 & PAHs form M e << [WCL] FTP Only a few x 1000 yrs L T eff Explain dual dust presence in [WCL] Rare overall Why crystalline silicates It should happen to H-rich CSs O-rich dust forms

H-Deficient Stars 2007[WC] evolution alternativesPage 15 ~2000 AU few few 10,000 AU Silicate dust in disk PAH outflow young PN few Ro The disk storage scenario (Cohen et al. 1999; Waters et al. 1998) TPs start C/O>1 & PAHs form M e << [WCL] FTP L T eff O-rich disk forms (long lived, crystalline silicates form) Explains the crystalline silicates No fine tuning No dual dust in [WCE] Who makes the disk? It should happen to H-rich CSs.

H-Deficient Stars 2007[WC] evolution alternativesPage 16 It’s not the chemistry! (extra slide for Falk) TPs start M e <<; C/O < 1 [WCL]’s UV radiation: CO is disassociated making C available; PAHs FTP L T eff O-rich outflow It should happen to H-rich CSs [WCE] could also have PAHs Make PAHs in O-rich flows Could explain SwSt1 (WC10 w/ O-rich PN)

H-Deficient Stars 2007[WC] evolution alternativesPage 17 Need for a causal & exclusive connection [WCL] associated with dual dust No H-rich CS associated with dual dust Solution: H-deficiency dual dust H-deficiency & dual dust something or,

H-Deficient Stars 2007[WC] evolution alternativesPage 18 H-deficiency causes the dual dust? TPs start M e <<; C/O > 1 or < 1 [WCL] wind is C-rich; mixes with PN makes PAHs FTP L T eff O-rich disk forms (long lived, crystalline silicates form) [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?

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

H-Deficient Stars 2007[WC] evolution alternativesPage 20 An AGB merger scenario for [WCs] - no FTP (De Marco & Soker 2002) CE merger: in-spiral + destruction + disk sheer mixing: O -> C change M e <<: AGB departure… L T eff TPs start O-rich disk forms by companion action … and makes the star H-def! post-CE: [WCL] A merger would not make Me << How do we get the H-deficiency? The event causes dual-dust and [WCL]

H-Deficient Stars 2007[WC] evolution alternativesPage 21 A multiple CE + merger scenario for [WCs]? CE: M e << C/O>1 & PAHs form L T eff TPs start O-rich disk forms by companion action Expansion + Merger + FTP post-CE binary (a < few R * ) Macc >> primary expands new CE No FTP from this mechanism (?) Event does not cause the PAHs The event causes [WCL] [WCL]

H-Deficient Stars 2007[WC] evolution alternativesPage 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).

H-Deficient Stars 2007[WC] evolution alternativesPage 23 Oh… and of course we need to stall the march of the [WCLs] PG1159 <- [WCE] <- [WCL] L T eff

H-Deficient Stars 2007[WC] evolution alternativesPage 24 The wider PN context (Nordhaus et al. 2006; Soker 2006)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 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.)

H-Deficient Stars 2007[WC] evolution alternativesPage 25 PlaNB collaboration

H-Deficient Stars 2007[WC] evolution alternativesPage 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.

H-Deficient Stars 2007[WC] evolution alternativesPage 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.

H-Deficient Stars 2007[WC] evolution alternativesPage 28 Evolution of 1-8 M o single stars: from the main sequence to white dwarf Iben 1985 sdOB stars =

H-Deficient Stars 2007[WC] evolution alternativesPage 29 CE outcome is a sensitive function of the exact evolutionary status of the primary Bottom-AGB Top-AGB Orbital planePerpendicular plane Binary Merger

H-Deficient Stars 2007[WC] evolution alternativesPage 30 OH ; Bujarrabal; HST M2-9; Balik; HST Extremely bipolar to point-symmetric … He2-401; Sahai; HST PKS285-02; Sahai; HST

H-Deficient Stars 2007[WC] evolution alternativesPage 31 Bipolar structure within spherical halos NGC6543; Corradi, Goncalves; NOT

H-Deficient Stars 2007[WC] evolution alternativesPage 32 3 common envelope simulations 1 Main Sequence Mass = 1.5 M o Bottom of the AGB Top of the AGB

H-Deficient Stars 2007[WC] evolution alternativesPage 33 Population synthesis: Comparison with mass dist’ns Predict: M CSPN > 0.55 M  Reasonable match to observations. What about M CSPN >~ 0.7 M  ?

H-Deficient Stars 2007[WC] evolution alternativesPage 34 Population synthesis: fraction of WD that go through a PN phase post-RGB WD Post-AGB no PN 77% of post-AGB stars have M > 0.55 M  and make a PN. post-AGB yes PN: 82% WD mass dist’n Liebert et al predicted CSPN mass dist’n

H-Deficient Stars 2007[WC] evolution alternativesPage The Mass Issue The mean CS mass is too high ( Mo). Gesiki & Zijlstra 2006CSPN mass distribution is very narrow and peaks at higher mass. Gesiki & Zijlstra 2006 Assuming that the PN kinematic age = the evolutionary age of the CS.

H-Deficient Stars 2007[WC] evolution alternativesPage 36 Other post-CE CSPN. (De Marco & Soker revised) Look out for the “SOMEHOW” M e << C/O>1 & PAHs form L T eff TPs start O-rich disk forms by companion action PAH formation in an O-rich WCLPN by mass- loss (SwSt1) FTP No merger, no [WCL] Yes dual dust. Prediction some post-CE CSPNe have dual dust CE

H-Deficient Stars 2007[WC] evolution alternativesPage 37 What do [WCL]s evolve into? L T eff [WCL] [WCE] w/ double dust PG1159 non-DAs [WCE] no double dust PG1159 Some PG1159 fast rotating

H-Deficient Stars 2007[WC] evolution alternativesPage 38 What about [WCEs] WELS and PG1159s? TPs start C/O>1 & PAHs form CE: M e << Macc >> expansion L T eff O-rich disk forms by companion action post-CE binary (P<<) CE+ Merger induces FTP: CS becomes [WCL] PAH formation in an O-rich WCLPN by mass-loss (SwSt1) CPD has a disk PG1159 stars are fast rotators

H-Deficient Stars 2007[WC] evolution alternativesPage 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?

H-Deficient Stars 2007[WC] evolution alternativesPage 40 The mass determination method From Teff and tkin determine stellar mass that reaches Teff in tkin. T eff = 40,000 K  kin = 12,000 yr L

H-Deficient Stars 2007[WC] evolution alternativesPage 41 This method should not work for FTP stars Undetected TP loop will make PN relatively large for the T eff - mass is underestimated by a variable amounts - spread the mass distribution, not make it peakier!! T eff = 40,000 K  kin = 12,000 yr kin = 30,000 yr kin = 23,000 yr L L L

H-Deficient Stars 2007[WC] evolution alternativesPage 42 In addition, the [WCLs]… A common envelope would by-pass the transition time, overestimating the mass. T eff = 40,000 K  kin = 12,000 yr kin = 1,000 yr CE happens here CS emerges at higher temperature after ~10 yr

H-Deficient Stars 2007[WC] evolution alternativesPage 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]

H-Deficient Stars 2007[WC] evolution alternativesPage 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

H-Deficient Stars 2007[WC] evolution alternativesPage 45 Post-AGBs with dual dust. (van Winckel 2003) CE: M e << C/O>1 & PAHs form L T eff TPs start O-rich disk forms by companion action post-CE binary (a > few tens R*) No merger, no [WCL] Yes dual dust.

H-Deficient Stars 2007[WC] evolution alternativesPage High H-def CS rates in “anomalous” environments (Zijlstra et al. 2006).In the Sagittarius Dwarf Spheroidal galaxy: 3 of 4 CSs have [WC] class (Zijlstra et al. 2006). (Gorny et al. 2004)In the bulge: more [WC] in general and more [WC11] in particular. (Gorny et al. 2004)

H-Deficient Stars 2007[WC] evolution alternativesPage 47 The Final Thermal Pulse (FTP) scenario (Werner & Herwig 2006) Low envelope mass inter-shell abundances random A few issues Bloecker 1995