random velocity of planetesimals is pumped up as high as the escape velocity of protoplanets. This high random veloc- On the ot in circular o多様な円盤から生まれる多様な惑星 ity makes the accretion process slow and ineﬃcient and thus Tgrow longer. This accretion ineﬃciency is a severe problem HD 192263 with Æ1 e1 for in situ f Mdisk T cont <Tdisk Tgrow<Tdisk case. It is di slingshot m 原始惑星系円盤の質量 circular orb the magneti may be wea disks may b Terrestria Jovian plan planetary a key process systems. We conﬁr holds in a Æsolid ¼ Æ1 ð ¼ 1=2; 3= 軌道長半径 (中心星からの距離) tions. We d Fig. 13.—Schematic illustration of the diversity of planetary systems systems dep against the initial disk mass for < 2. The left large circles stand for central disk proﬁle円盤の質量の違い → ガス惑星の数と位置の違い time stars. The double circles (cores with envelopes) are Jovian planets, and the others are terrestrial and Uranian planets. [See the electronic edition of the growth
タイプ I 惑星落下月質量∼10地球質量の天体に効くメカニズム天体が円盤に立てた密度波により角運動量を失う
タイプ II 惑星落下10地球質量以上の天体に効くメカニズム天体が円盤に溝を作り円盤とともに中心星に落下
earing continues through scattering. After orbital time scales and high inclinations. three categories: (i) hot Earth analogs interior to 00 million years the inner disk is composed Two of the four simulations from Fig. 2 the giant planet; (ii) Bnormal[ terrestrial planets contain a 90.3 M] planet on a low-eccentricity 巨大惑星の移動に伴う惑星系の変化 the collection of planetesimals at 0.06 AU, a between the giant planet and 2.5 AU; and (iii) M] planet at 0.12 AU, the hot Jupiter at 0.21 orbit in the habitable zone, where the temper- outer planets beyond 2.5 AU, whose accretion U, and a 3 M] planet at 0.91 AU. Previous ature is adequate for water to exist as liquid on has not completed by the end of the simulation. sults have shown that these planets are likely a planet_s surface (23). We adopt 0.3 M] as a Properties of simulated planets are segregated be stable for billion-year time scales (15). lower limit for habitability, including long-term (Table 1): hot Earths have very low eccentric-Many bodies remain in the outer disk, and ac- climate stabilization via plate tectonics (24). ities and inclinations and high masses because 巨大惑星が落下する際に 周囲の原始惑星の軌道を 大きくかき乱す they accrete on the migration time scale (105 多様な惑星系形成 niscent of the recently discovered, close-in 7.5 M] years), so there is a large amount of damping planet around GJ 876 (25), whose formation is during their formation. These planets are remi- also attributed to migrating resonances (26). g. 1. Snapshots in time of the evolution of one simulation. Each panel of each body’s inclination on the y-axis scale. The color of each dot ots the orbital eccentricity versus semimajor axis for each surviving body. corresponds to its water content (as per the color bar), and the dark inner he size of each body is proportional to its physical size (except for the dot represents the relative size of its iron core. For scale, the Earth’s water ant planet, shown in black). The vertical ‘‘error bars’’ represent the sine content is roughly 10j3 (28).
Weidenschilling &,Marzari (1996),,Lin,&軌道不安定による惑星系の変化 (t >~ 1My) 惑星間の重力の影響が , 積み重なって最終的に . e . final 互いの軌道が不安定化 a . ↓ a . GM * GM * 異なる惑星系へ GM * GM * GM * a1 a2 a3 a a Eccentric Planet の起源？