Common Envelope Evolution through Planetary Nebula Eyes Orsola De Marco American Museum of Natural History. Collaborators: H.E. Bond, M. Moe, M.-M. Mac Low, E. Sandquist, F. Herwig, R. Taam. Merging binaries. Simulations UKAFF. Outline.
Common Envelope Evolutionthrough Planetary Nebula Eyes
Orsola De Marco
American Museum of Natural History
Collaborators: H.E. Bond, M. Moe, M.-M. Mac Low, E. Sandquist, F. Herwig, R. Taam
Merging binaries. Simulations UKAFF
A twice-in-a-lifetime opportunity
AGB: R ~ 500-1500 Ro
RGB: R ~100-300 Ro
Unstable Roche Lobe overflow
Depending on the efficiency of the energy transfer from the companion to the CE (), one might get:
A short-period binary, or… a merged star
The existence of a CE phase is inferred by the presence of evolved close binaries: CVs, Type Ia SN, LMXB, post-RGB sdB binaries, and...
Binary CSPN, with P < 3-5 yr
If you are interested in the PN for themselves:
How many post-CE PN? How are they different from single or merged CSPN?
If you are interested in the CE interaction:
Can we use the post-CE CSPN to constrain our understanding of the CE interaction?
Summer 2004observations added 16 data points to IC4593 resulting ina likely period of 5.1 day! (Other periods not yet determined)
PN RV survey:10/11 RV variables (De Marco et al. 2004 & H. Bond’s talk): Most CSPN in close binaries !?
Could our finding be right and most/all PN derive from a CE?Rephrasing the question: Could most/all galactic PN derive from main sequence binaries that enter and survive an AGB CE?
# of stars in the Galaxy: 2.1 x 1011 (Total mass:Kulessa & Lynden-Bell 1992; IMF: Kroupa et al. 1993)Primaries w/ lifetime shorter than age of Galaxy: 7.6% (based on 9 Gyr:del Peloso et al. 2005 corresponding to M > 1.03 Mo: Schaller et al. 1992; Bressan et al. 1993)
Percentage of stars w/ companion: 60% (Duquennoy & Mayor 1; ie # of binary systems=0.375x2.1x1011)
Binaries w/ 100 Ro < a < 500 Ro: 12% (I.e. that enter CE on the AGB;Duquennoy & Mayor)
M1/M2 > 0.2: 73% (Duquennoy & Mayor 1991; I.e. secondary ejects the envelope even for low )
Mean age of primaries: 1.15 Gyr (Schaller et al. 1992; Bressan et al. 1993; for mean mass of 2.03Mo from Kroupa IMF with limits 1.03Mo and 10Mo)
PN visibility time ~ 20,000 yr (ESO catalogue)
# of post-CE binary CSPN ~ 9100 (OK within a factor of ~5)
# of PN in the Galaxy (actual): ~3000 (ESO catalogue + Parker & Phillips 1998)
# of PN in the Galaxy (estimated): 7200 +/- 1800 (Peimbert 1990)
Despite uncertainty, 9100 post-CE binaries, is commensurate with the # galactic PN, lending circumstantial support to the RV survey.
Some population syntheses (e.g., Han et al. 1995)predict only ~20% of all PN in close-binaries.Is this inconsistent with our earlier accounting?
If the majority of CSPN are post-CE binaries:
Where are the single (or merged) post-AGB stars?
The CE phase plays a fundamental role in CVs, Type Ia SN, LMXB, post-RGB sdB stars in close binaries, and close-binary CSPN.
Despite past work, out theoretical understanding of the CE interaction is still rudimentary.
In particular: what is ? We know it is not constant, but a function of stellar and system parameters.
Without knowing , population synthesis models cannot predict/explain period distributions and other characteristics of,e.g., CVs, Type Ia SN progenitors.
Past work in common envelope theory:
Ostriker 1975, Paczynski 1976 (proposal)eg, Rasio & Livio 1996 (analytical)eg, Taam & Sandquist 2000 (numerical)
Past work in common envelope observations:
e.g. Hillwig et al. 2002, Drake & Sarna 2003Sarna et al. 1995, Bleach et al. 2000
The determination of
De Marco et al. 2003 & in prep.
Code: Burkert & Bodenheimer 1993Method: Sandquist et al. 1998
4 common envelope tests
1 Main Sequence Mass = 1.5 Mo
Bottom of the AGBTop of the AGB - Thermal Pulse 10
Reminder: depending on the efficiency of the CE, the outcome can be:
A short-period binary, or… a merged star
The efficiency is measured by:
= EBin / Eg
~ 1 is more likely to result in a close binary.<< 1 is more likely to result in a merger.
Results:the outcome is a very sensitive function of initial parameters, including the evolutionary state of the primary.
highly variable, while population studies assume it is constant!
Less efficient: 0
More efficient: 1
The period distribution of post-CE populations, is a sensitive function of .
Period distribution of WD+MS post-CE systems from thetheoretical population synthesis models of Han et al. 1995 (Fig 4)
3 d < P < 100 d
P < 3 d
Theoretical period distributions using the new values can be compared to the period distributions of post-CE populations such as:
or post-AGB: CSPN
Post-RGB: sdB stars binaries
Maxted et al. 2001 Morales-Rueda et al. 2003
De Marco et al. (2004) and work in progress.
This calibration makes population simulations more reliable to understand theaction of magnetic breaking or gravitational wave radiation in “tightening” binariesleading to the onset of phenomena like CV behaviour or type Ia SN.
CE outcome is a sensitive function of the exact evolutionary status of the primary.
A 0.1-Mo companion
has little effect on a
bottom-of-the-AGB star, but is devastating for a top-of-the-AGB one …
… with 68% of the envelope lost in ~10 yr and a resulting binary. The mass lost (unbound mass on the grid) has a bipolar configuration (PN
We will also address (code FLASH [Fryxell et al. 2000]):
1) What happens to the companion in the final phase of the spiral-in?
useful in: (i) can low mass companions eject the envelope?
(formation of CVs with BD companions [Politano 2004]) (ii) can a planet change into a more massive object by accreting (e.g., Siess & Livio 1999)?
2) What happens when companions merge with the primary’s core? useful in: (i) Blue stragglers (Saffer et al. 2000)
(ii) R Coronae Borealis stars (Clayton 1996) (iii) Wolf-Rayet central stars (De Marco & Soker 2002) (iv) SN Type Ia (Langer et al. 2000)
(v) Other types of SN??? (suggestion by E.F. Brown)
Please send questions to: