1. Secular Evolution of Pre-Main Sequence Triples Erez Michaely Advisor : Prof. Hagai Perets Israel Institute of Technology, Haifa

2. Observations : Binaries Introduction Close Low Mass binaries are likely to be a part of a triple system [Tokovinin 2006] O stars: Period distribution favors shorter periods than Opik law (log uniform) [Sana 2012]

3. Triples are very common Introduction ~15% of all stars reside in triple [Raghavan 2010] Possibly >50% of stars with M>5M sun are in triples [Remage Evans 2011 ] Vast majority of multiple systems are hierarchical [Tokovinin 1997]

4. Hierarchical Triples Introduction

5. Previous Work : Eggleton & Kiseleva Introduction Kozai Cycles Tidal Friction Harrington 1968 Mazeh & Shaham 1979 Kiseleva et al. 1998 used KCTF on the Algol system Eggleton & Kiseleva 2001 and 2006 : KCTF might produce many close/contact binaries Facrycky & Treaine 2007 Perets & Naoz 2013 – planetesimals Many more... The calculation were made on MS systems

6. Previous Work : GR dissipation Introduction Work have been done also for compact objects Instead of tidal dissipation GR radiation [Blaes et al. 2002]

7. Pre Main Sequence properties Introduction Pre-MS Very big; size of giants Convective Contracts on a thermal timescale Good objects to undergo tidal friction

8. Pre Main Sequence properties Introduction

9. Secular Evolution scheme of Pre-MS triples Introduction 3 21 Pre-MS circular binary

10. Secular Evolution scheme of Pre-MS triples Introduction 3 21 Pre-MS contraction & Kozai oscillation

11. Secular Evolution scheme of Pre-MS triples Introduction 3 21 Eccentric orbit induces tidal interaction Dissipation of orbital energy

12. Tidal Friction Simple model for equilibrium tides Hut 1981 Model for equilibrium tides Introduction

13. Stellar evolution parameters taken from MESA Introduction MESA (Paxton 2010) stellar evolution code Radius as a function of time Radius of gyration

14. Secular dynamics up to an octupole expansion Introduction Double averaged Hamiltonian, secular code [Michaely & Perets 2014] following [Ford 2000,Blaes2002] Actually very similar to the code described by Silvia Two interacting rings Equation of motion for the orbital elements Relevant timescales

15. Hamiltonian up to octupole expansion Introduction Equation of motion for the orbital elements [Ford 2000]

16. Example KCTF on the Pre-MS for Low Mass Stars Preliminary results

17. KCTF on the Pre-MS for Low Mass Stars Preliminary results No Tides

18. KCTF on the Pre-MS for Low Mass Stars Preliminary results With Tides

19. Example KCTF on the Pre-MS for High Mass Stars Preliminary results

20. KCTF on the Pre-MS for High Mass Stars Preliminary results No Tides

21. KCTF on the Pre-MS for High Mass Stars Preliminary results With Tides

22. Example KCTF on the Pre-MS for High Mass Stars induce RLOF Preliminary results

23. With Tides KCTF on the Pre-MS for High Mass Stars induce RLOF

24. Coupling orbital energy with tidal interaction - helps Energy Budget Orbital energy is dissipated into the inner binary The energy deposited into the star in for of heat Heat inside the proto-star ‘help’ fight against the gravitational collapse The pre-MS is longer, hence the mechanism is more efficient Future work Kozai-Lidov Oscillations

25. Summary Triple dynamics and evolution is a reach field the implications on a variety of astrophysics aspects Secular code with mass loss / transfer and tidal friction and stellar evolution was developed Secular evolution in the Pre-MS phase is important Period distributions Mass function Systematic exploration of parameter space is available A lot more can be done Comments are welcomed Stay tuned...

26. Summary Thank you