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Massive Binaries

Massive Binaries

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Massive Binaries

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  1. A&A 507, 1 (2009) Archiv: 0910.1086 Selma de Mink Utrecht  Bonn STScI (Nov 2010) Massive Binaries and self enrichment of globular clusters Norbert Langer (Bonn) Onno Pols (Utrecht) Rob Izzard (Brussels)

  2. Introduction S.E. de Mink

  3. Globular clusters … not so simple as we thought they were • Multiple populations that differ in • composition and • possibly in age • 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) S.E. de Mink

  4. Simplified formation scenario 1. Initialcloudwith “normal” composition 2. Formation of the firstgenerationof stars 6. The multiple populations we seetoday. S.E. de Mink

  5. Simplified formation scenario 1. Initialcloudwith “normal” composition 2. Formation of the firstgenerationof stars 3. “Massive ”stars ejectpro-cessedmaterial 4. Polluting the cluster 5. Forming a secondgeneration. 6. The multiple populations we seetoday. S.E. de Mink

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

  7. Mass budget Kroupa 2001 S.E. de Mink

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

  9. Massivebinaries stars are also ... ... not as simple as we thoughttheywere hoped S.E. de Mink

  10. InteractingBinaries • The most massive star enrichesits inner layerswithproducts of proton capturereactions. S.E. de Mink

  11. De Mink et al. (2009a) InteractingBinaries He core Mg↓Al↑ “Strongly” processed O↓Na↑ “Mildly” processed C↓N↑ Unprocessed Li↓ • The most massive star enrichesits inner layerswithproducts of proton capturereactions. S.E. de Mink

  12. De Mink et al. (2009a) InteractingBinaries Unprocessed • The most massive star enrichesits inner layerswithproducts of proton capturereactions. • Whenitexpandsbeyond a critical radius, it is strippedfromitsentireenvelope. • The firstnon-enrichedlayers are accretedby the companion. S.E. de Mink

  13. De Mink et al. (2009a) Interacting Binaries Unprocessed Mildlyprocessed Stronglyprocessed • 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. S.E. de Mink

  14. Evidenceformass loss frombinaries • comes from a widevariety of observedsystemsand • seemsto be a commonphenomenon. Observational Evidence e.g. Iben+Livio93 Refsdal+74, Sarna93, deGreve+Linnell94, Figueiredo+94, vanRensbergen+06 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 30-70 km/s • Dust and clumps Gehrz+01, Smith+01,02, Grundstrom+07 • Post-interaction: common envelope ejection • Cataclysmic variables, X-ray binaries, double white dwarfs, double neutron stars, Planetary nebulae with binary cores • Interacting binaries • Algol type systems • Tests from eclipsing binaries S.E. de Mink

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

  16. De Mink et al. (2009a) Exampledetailed model Relative surface abundance Ejected mass (Msun) Ejected mass (Msun) Typical massive binary system: 20 Msunstar with a 15 Msun comp. in a 12 days orbit (Case B) Primary star loses 12 Msun • 1.5 Msun is accreted • 10.5 Msun is ejected Ejecta are • enriched in He, N, Na, Al • depleted in C, O, (Mg) S.E. de Mink

  17. Additionalremarks • 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

  18. Mass Budget S.E. de Mink

  19. Binary fraction • 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

  20. De Mink et al. (2009a) Binaries as sources of enrichment • Without commonly made assumptions • Normal IMF • No a very high fraction of veryfast rotators • No externalpollution • No extreme preferential loss of 1st generation stars S.E. de Mink

  21. De Mink et al. (2009a) Binaries as sources of enrichment MassiveBinaries: Assumingthat the complete envelope is processed and returned and that all stars above 10 Msun are in interactingbinaries S.E. de Mink

  22. De Mink et al. (2009a) Binaries as sources of enrichment MassiveBinaries: Assumingthat the complete envelope is processed and returned and that all stars above 10 Msun are in interactingbinaries Binaries canreturnmoreprocessedmassthanAGBandspinstars together. S.E. de Mink

  23. De Mink et al. (2009a) Binaries assourcesof enrichment Massive Binaries: Assumingthatthecompleteenvelopeisprocessedand returnedandthatallstarsabove10Msunareininteracting binaries Intermediate mass binaries: Lowermassstarsmayalsoprovideprocessedmaterialshowingsomeoftheanticorrellationsproducedatlower T. Binaries canreturnmoreprocessedmassthanAGBandspinstars together. S.E. de Mink

  24. Conclusion S.E. de Mink

  25. Conclusion Interacting stars are promisingsources forselfenrichment of globular clusters A&A 507, 1 (2009) Archiv: 0910.1086 • Interactions betweenmassivestarsandthereforemassstrippingarelikelyincenterofmassiveyoung clusters • Interactingstarscanejectmaterial • processedby H-burning • atlow velocities • inlarge amounts • Possiblymoreimportantthanthe previously suggestedsources (atleastintermsofejecta mass) • Relieveoftheneedforextremeadditional assumptions • atopheavy IMF • extremepolutionorpreferenialmass loss

  26. A&A 507, 1 (2009) Archiv: 0910.1086 S. E. de Mink S.E. de Mink