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
Introduction
Introduction Willems & Kolb Willems & Kolb (2004) 2004 PCEB, He-core WD
Introduction Willems & Kolb (2004) PCEB, CO- or O/Ne-core WD
Introduction PCEBs wide WDMS Willems & Kolb (2004)
Introduction MB (+GR) PCEB CE WD CV SSS WD DD SN Ia?
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
The sample: how to find it?
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
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)
The sample: stellar parameters 2 - Teff(WD) log g(wd) M(wd)
The survey: radial velocities Na λλ 8183.27,8194.81 doublet Hα emission Rebassa-Mansergas et al. (2007) Schreiber et al. (2008, 2010)
The survey: radial velocities 211 PCEBs and 1065 wide WDMS
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)
The survey: Porb distribution Neboť Gomez-Moran et al. (2011) Porb peaks at 8 h Majority with Porb < 1 d
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 http://www.sdss-wdms.org
CE evolution Eenv = α ΔEgr Packzynski (1976), Webbink (1984, 2008), Ivanova et al. (2013) Can we constrain the CE efficiency? PCEB
CE evolution Neboť Gomez-Moran et al. (2011)
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)
CE evolution Additional energy sources? IK Peg α > 1 (Porb = 21.72 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)
CE evolution: SDSSJ1211-0249 and SDSSJ2221+0029 Porb = 7.818 +- 0.002 d Porb = 9.588 +- 0.002 d Rebassa-Mansergas et al. (2012b)
CE evolution: evolutionary history The efficiency of recombination is not considered Uncertainties in Mwd and Twd are taken into account SDSSJ1211-0249 α(ce) = 0.21 1 SDSSJ2221+0029 α(ce) = 0.42 1
CE evolution: the energy budget IK Peg SDSSJ1211-0249 SDSSJ2221+0029 Porb (days) 21.7 7.8 9.6 Mwd (Msun) 1.19 0.52 0.54 Apparently not only long Porbs but also high-mass WDs
CE evolution: the energy budget Obtain the maximum Porb with and without recombination energy α(ce) free
The energy budget of CE Obtain the maximum Porb with and without recombination energy α(ce) free
The energy budget of CE
The energy budget of CE IK Peg Survey of PCEBs containing high mass WDs
Magnetic Braking GR GR+RMB different MB prescriptions GR+IMB GR+DMB PCEB CV Politano & Weiler (2006)
Magnetic Braking Schreiber et al. (2010) Strong evidence for DMB
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