Towards understanding the orbital architecture of multiple planetary systems

New Technologies for Probing the Diversity of Brown Dwarfs and Exoplanets Towards understanding the orbital architecture of multiple planetary systems Ji-Lin Zhou Dept. of Astronomy, Nanjing University Nanjing 210093，China，zhoujl@nju.edu.cn NJU GROUP H.G. Liu, S.Wang, H.Zhang J.V.Xie, G.Zhao, Y.Y.Chen Cooperate with D.N.C Lin et al. 2009.7.21,Shanghai

>350 planets detected(17 July2009) 38 multiple planet systems Detected Exoplanets (http://exoplanet.eu/) • Many hot planets; • Many planets in eccentric orbits;

Our solar system • Giant planets in moderate-distance orbits • Near circular orbits Q: What makes the difference between exoplanet and solar systems? • What we did: • Simulate the formation and evolution of planet systems • Adopt core-accretion scenario • Use N-body simulation---origin of eccentricities

Initial set up Modified solar nebular model (Hayashi 1980) -1 280 -1 snow line

Model: begin with ~40 isolation masses, Including gas accretion, type-I , type-II migration, gas disk depletion stall of type –I migration by boundary of Active/Dead zone (Kretke & Lin 2007) (see Ida & Lin’s papers for formulas)

Disk depletion time scale • 11 groups, with Tdep from 0.5Myr to 5Myr • Each group has 20 runs, so 20x11=220 runs of N-body simulations. • All the other parameters are standard, M_*=M_s,f_d=f_g=1, C_1=0.3, alpha=10-4…. • Hermit Code with regularization, merge (Aarseth 2003) • Evolution timescale: 5Myr

Results: M-a plot sim. obs. Ida & Lin 2008

a-e, e-M plots:only by N-body simulations sim. sim. obs. obs.

Semi-major axes distribution obs. sim. Two accumulations: ~0.05AU: inner disk age ~0.3AU: A/D boundary Inner edge of migration

M-distribution obs. Wright et al.2008 sim. • Lack of planets in 4-10Me, 30-70Me • Maximum M depends on fg

Eccentric distribution obs. • More planets in near circular orbits than those observed • can be fit by exponential law sim.

Correlation with No. of planets sim. sim. • Single planet: larger M, e • Multiple planets: smaller M, e obs. Wright et al.2008

Depends on gas depletion timescale eccentric orbits with hot planets Solar system Effect of disk: damp a, e I II III. New Category of Planetary systems? I: with Tdep< 1Myr: eccentric planet system II: with 1 Myr<T_dep< 3Myr: multiple planets, like solar system III. with T_dep> 3Myr: systems with hot planets

Evolutional track Tdep<1Myr distant, eccentric orbits 1Mr<Tdep<3Myr Type I system moderate, near-circular orbits Type II close, circular orbits Increasing disk survival time scale Type III Tdep>3Myr

IV. Conclusions • Through N-body simulation, the a-e distribution, etc., of observed exoplanets can be revealed; • Simulations shows lots of hot Super Earth planets; • The major factor that makes solar system so different with the observed exoplanet system is the depletion timescale of protoplanetary disk; • A new, evolutional category of planetary system is proposed, based on different depletion timescale of disk. See poster of Liu, Zhou, Wang (No.24) for more details, And other posters of our grroup: No.22-26,No…

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Towards understanding the orbital architecture of multiple planetary systems