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Based on Two planets orbiting the recently formed post-common envelope binary NN Serpentis

Evidence for planets orbiting the post-common envelope binary NN Serpentis Stefan Dreizler Institut für Astrophysik Göttingen. Based on Two planets orbiting the recently formed post-common envelope binary NN Serpentis A&A submitted

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Based on Two planets orbiting the recently formed post-common envelope binary NN Serpentis

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  1. Evidence for planets orbiting the post-common envelope binary NN SerpentisStefan DreizlerInstitut für Astrophysik Göttingen Based on Two planets orbiting the recently formed post-common envelope binary NN Serpentis A&A submitted K. Beuermann1, F. V. Hessman1 , S. Dreizler1, T. R. Marsh2, S.G. Parsons2, D.E. Winget3, G. F. Miller3, M. R. Schreiber4, W. Kley5, V. S. Dhillon6, S. P. Littlefair6, C.M. Copperwheat2, J. J. Hermes3 1) Göttingen, 2) Warwick, 3) Austin, 4) Valparaiso, 5) Tübingen, 6) Sheffield

  2. Exoplanets ≤ 500 exoplantes Various methods Growing number of planets around evolved stars ≈ 10% in binaries Recently: circum-binary planets

  3. A school project …

  4. NN Serpentis Haefner et al. 1989 PG1550+131 (Wilson et al. 1986) Porb = 3.12 hr (Haefner et al. 1989; MCCP) VLT imaging, spectroscopy (Haefner et al. 2004)

  5. Orbital ParametersParsons et al. 2010a a = 0.934 R TWD = 57,000 K MWD = 0.535 M D = 512 pc Msec = 0.111 M Age of WD ~ 106 yr i = 89.6°

  6. Eclipse Timing ResidualsQian et al. 2009 MCCP VLT Bialkow UltraCam Lijiang P = 7.6 years, a < 3.3 A.U., M = 11 MJupiter

  7. Eclipse Timing ResidualsParsons et al. 2010b MCCP VLT Bialkow UltraCam Lijiang Planetary solution rejected No satisfactory fit with linear ephemeris VLT point suspicious

  8. Revisiting the VLT Observations • Trailed FORS images (Haefner et al. 2004) 1125.7462 secs (±0.2 secs !)

  9. MONET/North Observations

  10. Timing Residuals MCCP VLT UltraCam Bialkow Lijiang MONET

  11. What the timing variations are not • Not due to complicated eclipse profile • Not due to stellar activity • Not due to Applegate’s mechanism • Spin-orbit coupling due to magnetic cycles and radius changes within the secondary • Time scale on decades or longer • Needs too much energy (Chen 2009) • Not due to apsidal motion • Precession of periastron due to tides • Amplitude t = Pbin ebin = 3577 s ebin OK with ebin~0.01 • Variation of the FWHM not seen • Period would be ~0.4 years

  12. McDonald Observations

  13. UltraCam Observations

  14. Model #1 : 3rd Body P = 22.6 years, e > 0.65 a = 6.9 A.U., M = 8.4 MJupiter

  15. Model #2 : 2 Bodies

  16. The 2+2-Body Solutions • Binary • Pdot < -10-13 (GR angular momentum loss OK) • Two stable 2+2 solutions (grid search) • Pb:Pc ≈ 2:1 ≈ 5:2 (±15%) • Reduced 2 0.90 0.91 • NN Ser b • eb 0  0 • Pb [years] 15.50±0.45 16.73±0.26 • ab [A.U.] 5.38±0.20 5.65±0.06 • Mb sin i [MJupiter] 6.89±0.54 5.93±0.40 • NN Ser c • ec 0.20±0.02 0.22±0.02 • Pc [years] 7.75±0.35 6.69±0.40 • ac [A.U.] 3.39±0.10 3.07±0.13 • Mc sin i [MJupiter] 2.24±0.38 1.61±0.27

  17. Orbital Histories of NN Ser A,B 0.7 A.U. 0.9 A.U. Red Giant Envelope Common Envelope Ejection

  18. Orbital History of NN Ser b,c • Binary Star System • ~2.1 Msun A star + M dwarf at ~1 A.U. (CE=0.25) • RGB expansion causes CE ejection ~1 million years ago • Planets around NN Ser A absorbed • 1st Generation (circumbinary): • NN Ser b,c at > ~3 A.U. • Drift outwards/near escape due to loss of 1.5 M from NN Ser A • Differential drift inwards due to frictional drag (gravitational), tidal forces • Dynamical evolution stops at radii ~3 & 5-6 A.U. with resonance condition between b & c

  19. A Primitive Evolution Simulation

  20. Orbital History of NN Ser b,c • 2nd Generation (circumbinary) : • Original planets at a < ~1 A.U. lost in RGB • Formation of planets in the metal rich and massive CE with 1.5 M • NN Ser b,c come into resonance as very young planets • Mixed : • Original planets at a < ~1 A.U. lost in RGB • Less massive planets at a ~ 2-6 A.U. survive CE and accretes from CE • 1st genaration plate might trigger planet formation in CE • NN Ser b,c come into resonance as rejuvinated/young planets

  21. Conclusions • The task of observing the variations and constraining the origin of the timing variations is very difficult • It helps to have lots of access to 1m and occational access to 2-3m telescopes • The eclipse time variations in NN Ser A/B are most simply explained as the timing effect due to two massive, circumbinary planets • The planets could either be 1st or 2nd generation (or both), depending upon the details of their interaction with the CE and the CE’s long-term evolution • Potentially many more circum-binary, post-common envelope planets to come http://solar-flux.forumandco.com/worlds-f12/edasich-s-work-t337.htm

  22. Common Envelope

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