Two planets orbiting the 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 K. Beuermann 1 , F. V. Hessman 1 , S. Dreizler 1 , T. R. Marsh 2 , S.G. Parsons 2 , D.E. Winget 3 , G. F. Miller 3 , M. R. Schreiber 4 , W. Kley 5 , V. S. Dhillon 6 , S. P. Littlefair 6 , C.M. Copperwheat 2 , J. J. Hermes 3 1) Göttingen, 2) Warwick, 3) Austin, 4) Valparaiso, 5) Tübingen, 6) Sheffield
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Two planets orbiting the post-common envelope binary NN Serpentis Evidence for planets orbiting the post-common envelope binary NN Serpentis Stefan Dreizler.
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Evidence for planets orbiting the post-common envelope binary
NN Serpentis
Stefan DreizlerInstitut für Astrophysik Göttingen
Based onTwo planets orbiting the recently formed post-common envelope
binary NN SerpentisA&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
• 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
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0.7 A.U.
0.9 A.U.
Orbital Histories of NN Ser A,B
Red Giant Envelope
Common Envelope Ejection
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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
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A Primitive Evolution Simulation
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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
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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