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DD Systems as Supernovae Ia Progenitors

DD Systems as Supernovae Ia Progenitors. L.Piersanti, A.Tornamb é, O.Straniero INAF – Osservatorio Astronomico di Teramo Inmaculada Dominguez Universitad de Granada. LII Congresso SAIt 4- 8 May 2008, Teramo - Italy. Type Ia Supernovae are produced by the thermonuclear disruption of CO

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DD Systems as Supernovae Ia Progenitors

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  1. DD Systems as Supernovae Ia Progenitors L.Piersanti, A.Tornambé, O.Straniero INAF – Osservatorio Astronomico di Teramo Inmaculada Dominguez Universitad de Granada LII Congresso SAIt 4- 8 May 2008, Teramo - Italy

  2. Type Ia Supernovae are produced by the thermonuclear disruption of CO WDs which approach MCh due to mass accretion from their companions in binary systems (Hoyle & Fowler 1960) SD Scenario DD Scenario The Evolutionary Scenario Explosion Mechanism: Delayed Detonation Model (Khakhlov 1991) We don’t know the mechanism triggering the transition! Progenitor System The companion is a normal star with an H-rich envelope The companion is a CO White Dwarf

  3. Accreting WD becomes very fast rotator Merging WDs Shrinkage of the orbits due to GWR Emission Dynamical mass transfer from M2 to M1 M2 disruptionand Accretion Disk formation Synchronization of the orbits! Angular Momentum deposition

  4. Final Outcomes DD Systems Rotation tunes the accretion rate! Mfin=1.49 M0!

  5. Dimmer events could be undetected No very Bright event in early type galaxies Differences in the total mass of DD Systems! Observational Evidence (Gallagher et a. 2005)

  6. Ingredients of our cooking 1) Large database of stellar evolutionary tracks (1-11 M0 – DM=0.1) 2) Salpeter mass function (a=-2.35) for the binary system total mass 3) Flat distribution for log(A) 4) q distribution according to a sample of local spectroscopic binaries 5) CE efficiency according to Zwart & Verbunt (1995)

  7. Results: I For a single SF burst Cumulative number of events

  8. Age=13 Gyr Age=5 107 yr Results: II Distribution of the mean mass as a function of time High mass DD Systems Low mass DD Systems

  9. Results: III Mass Distribution at various Age Single Star Formation Episode Continuous Stars Formation

  10. Models of differentially rotating WD are needed!!! Conclusions DD systems can be regarded as SNe Ia progenitor systems IF the effects of rotation are taken into account In fact … • Rotation triggers the accretion process, acting as a fine-tuning • mechanism 2. Due to rotation, Mtot of the exploding object can vary in the range 1.4-2.2 M0 3. High mass merging DD systems occurs only at short time after SF 4. Long term evolution is dominated by low mass DD systems

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