Formation and evolution of white dwarf binaries

Transcription

1 Formation and evolution of white dwarf binaries Alberto Rebassa-Mansergas Collaboration with Chile and UK: Matthias Schreiber, Boris Gaensicke, Monica Zorotovic, Stelios Pyrzas, Steven Parsons, Ada Nebot, Tom Marsh

2 Introduction

3 Introduction Willems & Kolb Willems & Kolb (2004) 2004 PCEB, He-core WD

4 Introduction Willems & Kolb (2004) PCEB, CO- or O/Ne-core WD

5 Introduction PCEBs wide WDMS Willems & Kolb (2004)

6 Introduction MB (+GR) PCEB CE WD CV SSS WD DD SN Ia?

7 Introduction WDMS are ideal systems to constrain current theories of CE and MB because they are: Numerous No accretion disc Accessible with 2-8m telescopes Well known stellar components

8 The sample: how to find it?

9 The sample: how to find it? Rebassa-Mansergas et al. (2010,2012,2013) >2300 WDMS found in DR8 χ2-s/n defined for 164 WDMS templates

10 The sample: stellar parameters M-dwarf templates (Beuermann et al. 2006) Observed WD templates (from SDSS DR4) WD model spectra (Koester et al. 2010) 1 - Sp Rebassa-Mansergas et al. (2007)

11 The sample: stellar parameters 2 - Teff(WD) log g(wd) M(wd)

12 The survey: radial velocities Na λλ , doublet Hα emission Rebassa-Mansergas et al. (2007) Schreiber et al. (2008, 2010)

13 The survey: radial velocities 211 PCEBs and 1065 wide WDMS

14 The survey: orbital periods WHT (ISIS) VLT (FORS2) M-Baade (IMACS) M-Clay (LDSS3) NTT (EFOSC) Gemini-N (GMOS) Gemini-S (GMOS) Rebassa-Mansergas et al. (2008)

15 The survey: Porb distribution Neboť Gomez-Moran et al. (2011) Porb peaks at 8 h Majority with Porb < 1 d

16 Summary >2300 from SDSS (DR8), ~98% complete Stellar parameters from SDSS spectra WD Teff, log(g), M, R MS Sp, R, M Radial velocities PCEB (211) or wide WDMS (1065) Follow-up Orbital period (74) Information available at

17 CE evolution Eenv = α ΔEgr Packzynski (1976), Webbink (1984, 2008), Ivanova et al. (2013) Can we constrain the CE efficiency? PCEB

18 CE evolution Neboť Gomez-Moran et al. (2011)

19 CE evolution α lower than assumed ~ 0.25? (Zorotovic et al. 2010, Ricker & Taam 2012) However, selection effects! We are expanding the survey towards FGK companions Politano & Weiler (2007)

20 CE evolution Additional energy sources? IK Peg α > 1 (Porb = days) Davis et al. (2010) Zorotovic et al. (2010) Atomic recombination energy Eenv = α(ce) ΔEgr α(re) E(re) Han et al. (1995) Under debate Webbink (2008), Soker & Harpaz (2003)

21 CE evolution: SDSSJ and SDSSJ Porb = d Porb = d Rebassa-Mansergas et al. (2012b)

22 CE evolution: evolutionary history The efficiency of recombination is not considered Uncertainties in Mwd and Twd are taken into account SDSSJ α(ce) = SDSSJ α(ce) =

23 CE evolution: the energy budget IK Peg SDSSJ SDSSJ Porb (days) Mwd (Msun) Apparently not only long Porbs but also high-mass WDs

24 CE evolution: the energy budget Obtain the maximum Porb with and without recombination energy α(ce) free

25 The energy budget of CE Obtain the maximum Porb with and without recombination energy α(ce) free

26 The energy budget of CE

27 The energy budget of CE IK Peg Survey of PCEBs containing high mass WDs

28 Magnetic Braking GR GR+RMB different MB prescriptions GR+IMB GR+DMB PCEB CV Politano & Weiler (2006)

29 Magnetic Braking Schreiber et al. (2010) Strong evidence for DMB

30 Conclusions White dwarf binaries are excellent systems to constrain the formation and evolution of all close compact binaries: CE evolution MB Also: M-R relations of WDs and low-mass stars Rotation-activity relation of low-mass stars Origin of low-mass WDs Planets around PCEBs