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

Orsola De MarcoOrsola De Marco

American Museum of Natural HistoryAmerican Museum of Natural History

H-Deficient Stars 2007 [WC] evolution alternatives Page 2

The bottom lineThe 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 alternatives Page 3

H-deficient post-AGB star classes in this talk: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

0

10

20

30

40

50

60

70

80

90

100

Carbon Helium Oxygen Hydrogen

H-Deficient Stars 2007 [WC] evolution alternatives Page 4

H-deficient post-AGB star classes on the H-deficient post-AGB star classes on the “loopy” HR diagram“loopy” HR diagram

[WCL][WCL][WCE][WCE]

PG1159PG1159

non-DAs (DAs?)non-DAs (DAs?)

BAs = SakuraiBAs = Sakurai

BAs = V605 AqlBAs = V605 Aql

BAs = A30,A78BAs = A30,A78 WELSWELS

Bloecker 1995; Bloecker 1995; but Detlef invented itbut Detlef invented it

• The FTP abundance predictions match

H-Deficient Stars 2007 [WC] evolution alternatives Page 5

But there are big problems …But there are big problems …

1. With the born again stars

2. With the [WCLs]

H-Deficient Stars 2007 [WC] evolution alternatives Page 6

An issue with the Born-Again stars 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)Wesson et al. (2003, 2007)

Bond & Pollacco 2004Bond & Pollacco 2004

130’’

50’’

1’’

H-Deficient Stars 2007 [WC] evolution alternatives Page 7

BAs: ONeMg novae?BAs: ONeMg novae?

Wesson et al. 2007Wesson et al. 2007

H-Deficient Stars 2007 [WC] evolution alternatives Page 8

Probably not, but…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)(Rauch) and CK Vul (Shara)(Shara)

Demonstrative cartoon pilfered from the webDemonstrative cartoon pilfered from the web

H-Deficient Stars 2007 [WC] evolution alternatives Page 9

BAs: a couple more problemsBAs: 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)(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 alternatives Page 10

[WCLs]: Their unique characteristics (part I)[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).

• No H-rich CSPN has the dual dust chemistry (though some pAGBs do - see later). (Cohen 2001) (Cohen 2001)

Waters et al. 1998 (Nature!)Waters et al. 1998 (Nature!)

H-Deficient Stars 2007 [WC] evolution alternatives Page 11

[WCLs]: The unique characteristics (part II)[WCLs]: The unique characteristics (part II)(Zijlstra 2001)(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 alternatives Page 12

[WCLs]: The unique characteristics (part III) [WCLs]: The unique characteristics (part III) (Zijlstra 2001)(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

H-Deficient Stars 2007 [WC] evolution alternatives Page 13

[WCLs]: The unique characteristics (part III) [WCLs]: The unique characteristics (part III) (Zijlstra 2001)(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

H-Deficient Stars 2007 [WC] evolution alternatives Page 14

Silicate dust outflow

PAH outflow

young PN

few 1000 - few 10,000 AU

few Rofew Ro

~2

00

0 A

U

The recent AGB departure scenario The recent AGB departure scenario (Cohen et al. 1999; Waters et al. 1998)(Cohen et al. 1999; Waters et al. 1998)

TPs start

C/O>1 & PAHs form

Me <<[WCL] FTP

Only a few x 1000 yrs

L

Teff

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 alternatives Page 15

~2000 AU

few 1000 - few 10,000 AU

Silicate dust in disk

PAH outflow

young PN

few Rofew Ro

The disk storage scenario The disk storage scenario (Cohen et al. 1999; Waters et al. 1998)(Cohen et al. 1999; Waters et al. 1998)

TPs start

C/O>1 & PAHs form

Me <<[WCL] FTPL

Teff

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 alternatives Page 16

It’s not the chemistry!It’s not the chemistry!(extra slide for Falk)(extra slide for Falk)

TPs start

Me <<; C/O < 1

[WCL]’s UV radiation:CO is disassociated making C available; PAHs

FTPL

Teff

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 alternatives Page 17

Need for a Need for a causal & exclusivecausal & exclusive connection connection

• [WCL] associated with dual dust

• No H-rich CS associated with dual dust

• Solution:

H-deficiency dual dust

H-deficiency &

dual dustsomething

or,

H-Deficient Stars 2007 [WC] evolution alternatives Page 18

H-deficiency causes the dual dust?H-deficiency causes the dual dust?

TPs start

Me <<; C/O > 1 or < 1

[WCL] wind is C-rich;mixes with PN makes PAHs

FTPL

Teff

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?

QuickTime™ and aYUV420 codec decompressor

are needed to see this picture.

Density greyscale Orbital Plane (~top view)

A common envelope interaction

QuickTime™ and aYUV420 codec decompressor

are needed to see this picture.

Density greyscale Perpendicular Plane (~side

view)

De Marco et al. 2003De Marco et al. 2003

1Mo topAGB starR=3AU

0.1Mo MS star

H-Deficient Stars 2007 [WC] evolution alternatives Page 20

An AGB merger scenario for [WCs] - no FTP An AGB merger scenario for [WCs] - no FTP (De Marco & Soker 2002)(De Marco & Soker 2002)

CE merger:in-spiral + destruction + disk sheer mixing: O -> C changeMe <<: AGB departure…

L

Teff

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 alternatives Page 21

A multiple CE + merger scenario for [WCs]? A multiple CE + merger scenario for [WCs]?

CE: Me <<

C/O>1 & PAHs form

L

Teff

TPs start

O-rich disk forms by companion action

Expansion + Merger + FTP

post-CE binary(a < few R*)

Macc >>primary expandsnew CE

No FTP from this mechanism (?)

Event does not cause the PAHs

The event causes [WCL]

[WCL]

H-Deficient Stars 2007 [WC] evolution alternatives Page 22

Summary of the flawed scenariosSummary 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 alternatives Page 23

Oh… and of course we need to stall the march Oh… and of course we need to stall the march of the [WCLs]of the [WCLs]

PG1159 <- [WCE] <- [WCL]L

Teff

H-Deficient Stars 2007 [WC] evolution alternatives Page 24

The wider PN contextThe wider PN context

• Axisymmetric PNe need an angular momentum source - companion or accretion from a pre-formed disk. (Nordhaus et al. 2006; Soker 2006)(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 39WYIN 3.5 m telescope [OIII] (G. Jacoby)

Hubble 5HST [OII]/[NII]/[OIII](Balik, Ike, Mellema)

NGC6826 HST [NII]/[OIII]/V(Balick et al.)

H-Deficient Stars 2007 [WC] evolution alternatives Page 25

PPlaNlaNBB collaborationcollaboration

H-Deficient Stars 2007 [WC] evolution alternatives Page 26

We have partial matchesWe 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, Jody Foster (Ellie Harroway) in the movie Contact, failing to join together the many pages of instructions.failing to join together the many pages of instructions.

H-Deficient Stars 2007 [WC] evolution alternatives Page 27

We are not there yetWe 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.Ellie eventually figures out that the pages have to be joined in 3D.

H-Deficient Stars 2007 [WC] evolution alternatives Page 28

Evolution of 1-8 MEvolution of 1-8 Moo single stars: single stars:

from the main sequence to white dwarffrom the main sequence to white dwarf

Iben 1985Iben 1985

sdOB stars =

H-Deficient Stars 2007 [WC] evolution alternatives Page 29

CE outcome is a sensitive function of the CE outcome is a sensitive function of the exact evolutionary status of the primaryexact evolutionary status of the primary

Bottom-AGB

Top-AGBTop-AGB

Orbital plane Perpendicular plane

Binary

Merger

H-Deficient Stars 2007 [WC] evolution alternatives Page 30

OH321.8+4.2; Bujarrabal; HST

M2-9; Balik; HST

Extremely bipolar to point-symmetric …Extremely bipolar to point-symmetric …

He2-401; Sahai; HST

PKS285-02; Sahai; HST

H-Deficient Stars 2007 [WC] evolution alternatives Page 31

Bipolar structure within spherical halosBipolar structure within spherical halos

NGC6543; Corradi, Goncalves; NOT

H-Deficient Stars 2007 [WC] evolution alternatives Page 32

AGB star1 Companion α

Model Core Envelope Envelope MassName Mass Mass Radius ( )Mo

( )Mo ( )Mo ( )AU ~1150 Period days

. bott AGB 0.56 0.69 1.85 0.1 -

. bott AGB 0.56 0.69 1.85 0.2 0.13 top AGB 0.60 0.44 3.00 0.1 0.87

3 common envelope simulations3 common envelope simulations

1 Main Sequence Mass = 1.5 Mo

Bottom of the AGBBottom of the AGBTop of the AGBTop of the AGB

H-Deficient Stars 2007 [WC] evolution alternatives Page 33

Population synthesis:Population synthesis:Comparison with mass dist’nsComparison with mass dist’ns

• Predict: MCSPN > 0.55 M

• Reasonable match to observations.

• What about

MCSPN >~ 0.7 M?

H-Deficient Stars 2007 [WC] evolution alternatives Page 34

Population synthesis:Population synthesis:fraction of WD that go through a PN phasefraction of WD that go through a PN phase

post-RGB WD

Post-AGB no PN

77% of post-AGB starshave M > 0.55 M andmake a PN.

post-AGByes PN: 82%

WD mass dist’nLiebert et al. 2005

predictedCSPN mass dist’n

H-Deficient Stars 2007 [WC] evolution alternatives Page 35

2. The Mass Issue2. 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 2006Gesiki & Zijlstra 2006

• Assuming that the PN kinematic age = the evolutionary age ofthe CS.

H-Deficient Stars 2007 [WC] evolution alternatives Page 36

Other post-CE CSPN. Other post-CE CSPN. (De Marco & Soker 2002 - revised) Look out for the “SOMEHOW”(De Marco & Soker 2002 - revised) Look out for the “SOMEHOW”

Me <<

C/O>1 & PAHs form

L

Teff

TPs start

O-rich disk forms by companion action

PAH formation in

an O-rich WCLPNby 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 alternatives Page 37

What do [WCL]s evolve into? What do [WCL]s evolve into?

L

Teff

[WCL][WCE] w/ double dust

PG1159

non-DAs

[WCE] no double dust

PG1159

Some PG1159 fast rotating

H-Deficient Stars 2007 [WC] evolution alternatives Page 38

What about [WCEs] WELS and PG1159s? What about [WCEs] WELS and PG1159s?

TPs start

C/O>1 & PAHs form

CE: Me <<

Macc >>expansion

L

Teff

O-rich disk forms by companion action

post-CE binary (P<<)

CE+ Merger induces FTP: CS becomes [WCL]

PAH formation in an O-rich WCLPNby mass-loss (SwSt1)

CPD-568032 has a disk

PG1159 stars are fast rotators

H-Deficient Stars 2007 [WC] evolution alternatives Page 39

pAGB binaries with double dust and diskspAGB 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 alternatives Page 40

The mass determination methodThe mass determination method

• From Teff and tkin determine stellar mass that reaches Teff in tkin.

Teff = 40,000 K

kin = 12,000 yr

L

H-Deficient Stars 2007 [WC] evolution alternatives Page 41

This method should not work for FTP starsThis 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!!

Teff = 40,000 K Teff = 40,000 K Teff = 40,000 K

kin = 12,000 yr kin = 30,000 yrkin = 23,000 yr

L LL

H-Deficient Stars 2007 [WC] evolution alternatives Page 42

In addition, the [WCLs]…In addition, the [WCLs]…

• A common envelope would by-pass the transition time, overestimating the mass.

Teff = 40,000 K Teff = 40,000 K

kin = 12,000 yr kin = 1,000 yrCE happens here

CS emerges at higher temperature after ~10 yr

H-Deficient Stars 2007 [WC] evolution alternatives Page 43

Masses: conclusionsMasses: 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 alternatives Page 44

The masses of [WC]s The masses of [WC]s (Gesiki & Zijlstra 2006)(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 alternatives Page 45

Post-AGBs with dual dust. Post-AGBs with dual dust. (van Winckel 2003)(van Winckel 2003)

CE: Me <<

C/O>1 & PAHs form

L

Teff

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 alternatives Page 46

1. High H-def CS rates in “anomalous” 1. High H-def CS rates in “anomalous” environmentsenvironments

• In the Sagittarius Dwarf Spheroidal galaxy: 3 of 4 CSs have [WC] class (Zijlstra et al. 2006).(Zijlstra et al. 2006).

• In the bulge: more [WC] in general and more [WC11] in particular. (Gorny (Gorny

et al. 2004)et al. 2004)

H-Deficient Stars 2007 [WC] evolution alternatives Page 47

The Final Thermal Pulse (FTP) scenario The Final Thermal Pulse (FTP) scenario (Werner & Herwig 2006)(Werner & Herwig 2006)

• Low envelope mass

• inter-shell abundances

• random

• A few issues

Bloecker 1995Bloecker 1995