Stellar Duets: How Companions Shape the Life and Evolution of Stars Orsola De Marco American Museum of Natural History February 18th, 2005 Merging binaries. Simulations UKAFF
The Question that drives us:How does binarity change stellar evolution? Part 1: The theoretical “shopping list”: What we would like to know about binary interactions Part 2: An experimental test: PN Central Star binarity
Evolution of 1-8 Mosingle stars:from the main sequence to white dwarf sdOB stars = Iben 1985
A twice-in-a-lifetime opportunity R AGB: R ~ 500 Ro R RGB: R ~100 Ro
Roche Lobe overflow Common envelope
The common envelope efficiency parameter = EBin / Eg
~ 1 < 1 Short-period binary Merged star
The common envelope phase is inferred by the presence of evolved short-period binaries (CV, Type Ia SN, LMXB ...) 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
Shopping list item 1: what can we find out with current codes Common envelope efficiency fa useful in: (i) populations synthesis codes: prediction binary populations characteristics (ii) N-body codes: binaries in clusters, e.g.: 47 Tuc DSS/Chandra (G. Pooley)
Initial common envelope simulations(De Marco et al. 2003) Code: Burkert & Bodenheimer 1993Method: Sandquist et al. 1998 6 AU Companion's orbit E. Sandquist AGB star F. Herwig M.-M. Mac Low R. Taam
Bench: 0.1Mo + TP1 Sync: 0.1Mo + TP1 0.2Mo: 0.2Mo + TP1 TP10: 0.1Mo + TP10
68% of envelope lost in ~10 yr. Final configuration highly bipolar Bench vs TP10: different AGB star Bench TP10 Orbital Perpendicular
is testable (Yungelson et al. 1993) sdOB stars: 70% binaries. Period distribution peaks around 1 dayMaxted et al. 2001 Morales-Rueda et al. 2003
An observational parenthesis sdOB stars = binaries sdOB stars = blue HB stars blue HB stars = binaries Stellar binarity: the solution of the the “second parameter” problem in globular clusters Observations in hand. with D. Zurek, J. Ouellette, J. Hurley, T. Lanz and M. Shara Rey et al. 2001
Shopping list items 2 and 3: next code FLASH (Fryxell et al. 2000) 1) What happens in the deep interior of the primary? 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 (e.g., Siess & Livio 1999)? 2) What happens when stars merge. 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)
Evolution of 1-8 Mo stars from main sequence to white dwarf Iben 1985
Observed PN morphologies 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.) 5 ly Spherical (10%) Bipolar (11%) Elliptical (79%)
PN Halos 2.5 pc NGC6543 HST/NOT [OIII]/[NII]/Ha. (P. Harrington, R. Corradi)
The PN formation scenarios to explain the morphology • Interactive winds scenario (Kwok 1982; Balick 1987). Needs fast rotation and/or magnetic fields to create axi-symmetric AGB mass-loss (e.g. Garcia-Segura et al. 2003). • Hole punching scenario (Sahai & Trauger 1998). Needs fast outflows to punch holes into symmetric AGB mass-loss (e.g., Garcia-Arredondo & Frank 2004). What is the origin of the axi-symmetric AGB mass-loss and the outflows?
Binary star can create rotation, magnetic fields, jets and gravitational focussing. Binarity of central stars provides a potential explanation of PN morphology. But where are the binary central stars?
So: How many PN have binary central stars? % Intermediate periods ? 10 Ciardullo et al. 1999 2000< P < 30,000 yr Bond 2000 P < 3 days Period
2002 the hunt starts: radial velocity survey of central stars of PN 3.6 m WYIN G. Jacoby H. Bond A. FlemingO. De Marco D. Harmer
And they are analyzed like this... The data look like this
Periods must be determined, “it is the only way to be sure” Binary fraction: 10/11 ~ 90% % 90 High proportion of binarity for periods < 100 d 10 Ciardullo et al. 1999 2000< P < 30,000 yr Ciardullo et al. 1999 2000 > P > 30,000 yr Bond 2000 P < 3 days Bond 2000 P < 3 days Period
Periods must be determined, “it is the only way to be sure” Binary fraction: ~ 90% Periods: “short”Periods peak somewhere 3 d < P < 100 d % 3 d < P < 100 d 10 Ciardullo et al. 1999 2000 < P < 30,000 yr Ciardullo et al. 1999 2000 > P > 30,000 yr Bond 2000 P < 3 d Period
“There are alternatives to fighting…” He 2-113 HST/PC1 H Sahai et al. 2000
HST: Reflected light at 0.6 m He 2-113 HST/HRC F606
HST: Reflected light at 0.8 m He 2-113 HST/HRC F814
VLT: dust emission at 3.5m He 2-113 VLT/NACO L band
VLT: dust emission at 4.8m He 2-113 VLT/NACO M band
VLT: dust emission at 8.7m He 2-113 VLT/MIDI ACQ @ 8.7 m VLT Interferometer MIDIresolution 7mas Double-dust project with Olivier Chesneau
Consequences of higher binarity • New basis for the understanding of PN morphology. • Another puzzle for stellar evolution? • Constraint on Common Envelope efficiency . • New constraint on population theory (e.g., prediction SN Type Ia) and N-body simulations.
2700 AU Further impact of AGB binarity • Prevention of 3rd-dredge-up: • Different galactic carbon, oxygen and s-process element yields. Consequences for models of galactic chemical evolution (e.g. Dwek 1998). • Presence of circumstellar disks: • PAH formation: environment-dependent. PAH yields important for molecular cloud formation (Wolfire et al 1995). • Organic molecules formation/evolution in AGB, proto-PN and PN (Kwok et al. 1999). • SiC grains in proto-PN and in presolar grains (Speck & Hoffmeister 2004, Clayton 2003). Red Rectangle HST H. van Winkel Orion proplyd/ HST
Summary Part 1 • CE simulations on a broad scale: sensitivity to initial conditions, calculation. • Start new generation of calculations: small companions, mergers. • CE calculations assist population syntheses that predict binary classes (CV, SN Type Ia) and N-body simulations.
Summary Part 2 • PN binarity: explanation of morphology, challenge in stellar evolution, PN period-distribution: test of (AGB). • (sdOB period-distribution: test of (RGB), solution to second parameter problem in globular clusters??) • AGB binarity: altered stellar yields of atoms, molecules and minerals.
He2-138 HST/Ha (R. Sahai) Inner parts of the PN
Counting stars on the back of an envelope # of stars in the Galaxy: 1011 (Duquennoy & Mayor 1991: ~60% binaries) Primaries w/ lifetime shorter than age of the universe: 1010 yr Primaries w/ companion < 500 Ro: (Duquennoy & Mayor: ~25%) Mean age of stars: 10 Gyr PN visibility time: < 50,000 yr # of PN with close binary central stars: < 12,500 # of PN in the Galaxy: 10,000 +/- 4000 (Jacoby 1986) Some binaries will merge, some will never ascend AGB. Some population syntheses predict lower PN binary fraction (e.g., Yungelson et al. 1993).
TP10 simulation: density contour plot Orbital plane Perp. plane 1000 days 2000 days 3000 days 4000 days 68% of envelope lost in ~10 yr. Final configuration highly bipolar