and self enrichment of globular clusters Norbert Langer (Bonn) Onno Pols (Utrecht) Rob Izzard (Brussels) Norbert Langer (Bonn) Onno Pols (Utrecht) Rob Izzard (Brussels) Selma de Mink Utrecht  Bonn  STScI (Nov 2010) Selma de Mink Utrecht  Bonn  STScI (Nov 2010) A&A 507, 1 (2009) Archiv: A&A 507, 1 (2009) Archiv:

S.E. de Mink

M ultiple populations that differ in  composition and  possibly in age M ultiple populations that differ in  composition and  possibly in age S.E. de Mink … not so simple as we thought they were Stellar abundances e.g. Cohen+78, Gratton+04, Carretta+09ab Color magnitude diagrams e.g. Bedin+04, D’Antona+05, Piotto+07 Stellar rotation  natural explanation some features of intermediate-age clusters? Bastian & De Mink (2009 ) Stellar rotation  natural explanation some features of intermediate-age clusters? Bastian & De Mink (2009 )

1. Initial cloud with “normal” composition 2. Formation of the first generation of stars 6. The multiple populations we see today. S.E. de Mink

1. Initial cloud with “normal” composition 2. Formation of the first generation of stars 3. “Massive ”stars eject pro- cessed material 4. Polluting the cluster 5. Forming a second generation. 6. The multiple populations we see today. S.E. de Mink

Requirements ejecta I.Low velocity to remain within the potential well of the cluster II.Processed by H-burning at high temperature e.g. Prantzos+07 I.Low velocity to remain within the potential well of the cluster II.Processed by H-burning at high temperature e.g. Prantzos+07 Challenges Composition Amount e.g. Gratton+04, D’Antona+Caloi08 Composition Amount e.g. Gratton+04, D’Antona+Caloi08 Proposed sources I.Massive AGB stars: e.g. Cottrell+DaCosta+81, Ventura+01 II.Spin stars: fast rotating massive stars e.g. Decresin+07 I.Massive AGB stars: e.g. Cottrell+DaCosta+81, Ventura+01 II.Spin stars: fast rotating massive stars e.g. Decresin+07

S.E. de Mink Kroupa 2001

S.E. de Mink Ciotti+91, D’Ercole+08 Prantzos+Charbonnel06, Decressin+07 Assuming all stars rotate fast! (>0.8 break-up) Assuming all stars rotate fast! (>0.8 break-up) Assuming all 4- 9 M sun stars ar single and contribute Anomalous IMF ? Strong preferential loss of normal stars ? External pollution ? Anomalous IMF ? Strong preferential loss of normal stars ? External pollution ? Alterative source?

stars are also not as simple as we thought they were S.E. de Mink hoped

- The most massive star enriches its inner layers with products of proton capture reactions. S.E. de Mink

- The most massive star enriches its inner layers with products of proton capture reactions. He core “Strongly” processed “Mildly” processed Unprocessed C↓N↑ O↓Na↑ Mg↓Al↑ Li↓ S.E. de Mink De Mink et al. (2009a)

- The most massive star enriches its inner layers with products of proton capture reactions. - When it expands beyond a critical radius, it is stripped from its entire envelope. - The first non-enriched layers are accreted by the companion. Unprocessed S.E. de Mink De Mink et al. (2009a)

- The most massive star enriches its inner layers with products of proton capture reactions. - When its expands beyond a critical radius, the is stripped from its entire envelope. - The first non-enriched layers are accreted by the companion. - Processed material is shedded from the system at low velocity. Strongly processed Mildly processed Unprocessed S.E. de Mink De Mink et al. (2009a)

I.Post-interaction: common envelope ejection  Cataclysmic variables, X-ray binaries, double white dwarfs, double neutron stars, Planetary nebulae with binary cores I.Interacting binaries  Algol type systems  Tests from eclipsing binaries S.E. de Mink Refsdal+74, Sarna93, deGreve+Linnell94, Figueiredo+94, vanRensbergen+06 e.g. Iben+Livio93 De Mink, Pols, Hilditch (2007) “Show case”: Massive interacting binary: RY Scuti Circum-binary disk (1AU), Nebula (2000 AU) Rich in He, N, Poor in O, C Velocity km/s Dust and clumps Gehrz+01, Smith+01,02, Grundstrom+07 Evidence for mass loss from binaries - comes from a wide variety of observed systems and - seems to be a common phenomenon. Evidence for mass loss from binaries - comes from a wide variety of observed systems and - seems to be a common phenomenon.

3D Hydro simulations Evolutionary calculations -Expansion -> contact -Spin up S.E. de Mink Ultich+Burger76, Flannery+Ulrich77 Packet81, Barai+04, Petrovic+05 With courtesy of D. Bisikalo e.g. Nazarenko+Glazunova06, Zhilkin+Bisikalo09 Utrecht/Bonn binary stellar evolution code  Stellar evolution, mass loss, Extensive nucleosynthetic network, Mass and angular momentum transfer, Effects of tides, Effects of rotation De Mink, et al. 2009b, Yoon+06, Petrovic+05, Heger+00, Langer

Typical massive binary system: 20 M sun star with a 15 M sun comp. in a 12 days orbit (Case B) Primary star loses 12 M sun -1.5 M sun is accreted M sun is ejected Ejecta are -enriched in He, N, Na, Al -depleted in C, O, (Mg) S.E. de Mink Ejected mass (M sun ) Relative surface abundance Ejected mass (M sun ) De Mink et al. (2009a) Mass ejected slowly (M sun ) Binary 10.5 Spin star 1.7

 Evolution was followed until end of the evolution of the primary, but the secondary can still pollute the cluster as a spin star by reverse mass transfer  We assumed slow initial rotation. Fast rotation would induce extra mixing and could pollute an even larger fraction of the envelope S.E. de Mink

Currently not very high (among the low mass stars!) What about the massive stars? close binary fraction > 50% in nearby OB associations + open clusters Even higher in dense cores of globular clusters? -Initial/quick Mass segregation -Early core collapse -Dynamical interactions of stars and gas (dissipative!) -… S.E. de Mink

Without commonly made assumptions Normal IMF No a very high fraction of very fast rotators No external pollution No extreme preferential loss of 1st generation stars Without commonly made assumptions Normal IMF No a very high fraction of very fast rotators No external pollution No extreme preferential loss of 1st generation stars S.E. de Mink De Mink et al. (2009a)

Massive Binaries: Assuming that the complete envelope is processed and returned and that all stars above 10 Msun are in interacting binaries S.E. de Mink De Mink et al. (2009a)

Massive Binaries: Assuming that the complete envelope is processed and returned and that all stars above 10 Msun are in interacting binaries S.E. de Mink De Mink et al. (2009a) Binaries can return more processed mass than AGB and spin stars together.

Intermediate mass binaries: Lower mass stars may also provide processed material showing some of the anticorrellations produced at lower T. Massive Binaries: Assuming that the complete envelope is processed and returned and that all stars above 10 Msun are in interacting binaries Binaries can return more processed mass than AGB and spin stars together. S.E. de Mink De Mink et al. (2009a)

S.E. de Mink

Interactions between massive stars and therefore mass stripping are likely in center of massive young clusters Interacting stars can eject material -processed by H-burning -at low velocities -in large amounts Possibly more important than the previously suggested sources (at least in terms of ejecta mass) Relieve of the need for extreme additional assumptions -a top heavy IMF -extreme polution or preferenial mass loss A&A 507, 1 (2009) Archiv: A&A 507, 1 (2009) Archiv:

S.E. de Mink A&A 507, 1 (2009) Archiv: A&A 507, 1 (2009) Archiv: