NHK カルチャー講座「惑星科学最前線 ～多様な衛星の多様な起源～」第２回

NHK カルチャー梅田教室にて、衛星形成に関する講座を行ってきました。そのときに用いた講演資料です。

Transcript

1. 2020೥9݄27೔ɹNHKΧϧνϟʔകాڭࣨ@Zoom ࿭੕Պֶ࠷લઢ ɹʙଟ༷ͳӴ੕ͷଟ༷ͳىݯʙ ژ౎େֶ Ӊ஦෺ཧֶڭࣨɹࠤʑ໦وڭ
2. ༷ʑͳӴ੕ܗ੒࿦ • δϟΠΞϯτΠϯύΫτʢ݄ɾΧϩϯʣ • प࿭੕ԁ൫ʢΨϦϨΦӴ੕ɾλΠλϯʣ • Ϧϯάʢڊେ࿭੕ͷنଇӴ੕ͷҰ෦ʣ • ั֫ʢڊେ࿭੕ͷෆنଇӴ੕ɾτϦτϯʣ • ະ֬ఆʢՐ੕Ӵ੕ɾఱԦ੕Ӵ੕ʣ • ଠཅܥ֎ͷӴ੕ܗ੒࿦ʹ޲͚ͯ
3. ༷ʑͳӴ੕ܗ੒࿦ • δϟΠΞϯτΠϯύΫτʢ݄ɾΧϩϯʣ • प࿭੕ԁ൫ʢΨϦϨΦӴ੕ɾλΠλϯʣ • Ϧϯάʢڊେ࿭੕ͷنଇӴ੕ͷҰ෦ʣ • ั֫ʢڊେ࿭੕ͷෆنଇӴ੕ɾτϦτϯʣ • ະ֬ఆʢՐ੕Ӵ੕ɾఱԦ੕Ӵ੕ʣ • ଠཅܥ֎ͷӴ੕ܗ੒࿦ʹ޲͚ͯ
4. ଠཅܥͷ୅දతͳӴ੕ͨͪ (c) Wikipedia
5. ڊେ࿭੕ͷنଇӴ੕ (c) Malaga Bay
6. Ӵ੕Τϯέϥυε ණཻͱਫৠؾ͔ΒͳΔؒܽઘ ӷମͷਫɾ༗ػ୸ૉɾ஠ૉͷଘࡏ͕֬ೝ (c) NASA (c) NASA (c) Wikipedia ஍ٿͷ೤ਫ෾ग़޸ʢੜ໋ൃੜͷ৔ʣͱྨࣅ
7. oon forms at rR (moon 2). rapidly, approaches moon 2rH /r, moon 1 is too far away to accrete a newly formed moon before this new moon leaves the ~100 orbits. Also, qd < 0.1D provided D < 6.7 × 10−3. This is always the case around giant plan- ets (see below and SM 7), and it justifies the assumption that D and tdisk are constant. After Dd is reached, a third moon appears in the sys- tem, and the discrete regime ends. As moons of fixed mass (produced by the discrete regime) appear successively at a given radius, they migrate outward with decreasing rate, and hence their mutual distance decreases; eventually, they merge. Therefore, moons of dou- ble mass are periodically formed, migrate out- ward, merge again, and so on. Assuming that the satellites do not perturb each other’s orbit, mergers occur hierarchically—this is the “py- ramidal regime” (SM 6). The moons’ masses increase with distance, and an ordered orbital ar- chitecture settles. In the region r < r2:1 = 22/3rR , the migration is controlled by the disk’s torque (Eq. 3); then the mass-distance relation fol- lows M º D1.8, and the number density of moons is proportional to 1/D (SM 6.1). Consequently, just outside rR , an accumulation of small moons is expected, consistent with observations (Fig. 1A). Beyond r2:1 , the migration is controlled by the planet’s tides and M º r3.9 (SM 6.2). This specific architecture is a testable obser- vational signature of this process. A compari- son with today’s giant planet systems of regular moons reveals a very good match for Saturn, Uranus, and Neptune (Fig. 1B). Neptune’s inner Oberon (except Cupid and Mab, out of scale). Neptune: a, Galatea, Larissa, and Proteus. Jupiter: Metis, Adrastea, opa, Ganymede, and Callisto. (A) Mass as a function of four systems do not extend all the way down to the l line), but a pile-up of small satellites is observed at a oche limit, rR ). The mass increases from zero with the consistently with the mean density of satellites, or with the orbit of the closest one (SM 1). For Saturn, Uranus, and Neptune, rR = 140,000, 57,300, and 44,000 km, respectively. Short dashed curves: our model for the pyramidal regime Q(D) (eq. S25, SM 6.3): for D < D2:1 , q º D9/5 ; for D > D2:1 , q º (D + 1)3.9, where D2:1 = 0.59 is marked by the vertical dashed line. Jupiter’s system does not fit well and is not shown (SM 7.3). e s, e- H n. ay ss st e, e n- e y ss e: as w ). n- t- ), k c . n > m c . rc events between moons of similar masses. on November www.sciencemag.org Downloaded from The Astrophysical Journal, 799:40 (15pp), 2015 January 20 H Figure 5. (Continued) 1.8 2 aR ] the first satellite is formed on the orb This small companion was captured into the first satellite was still near the disk Ϧϯά͔ΒͷӴ੕ܗ੒ [Crida & Charnoz, Science, 2012] [Hyodo & Otsuki, ApJ, 2015]
8. ~100 orbits. Also, qd < 0.1D provided D < 6.7 × 10−3. This is always the case around giant plan- ets (see below and SM 7), and it justifies the assumption that D and tdisk are constant. After Fig. 1. Distribution of the regular satellites of the giant planets. Saturn: 9 satellites from Pandora to Titan. Uranus: (A) 18 from Cordelia to Oberon; (B) 14 satellites, from Bianca to Oberon (except Cupid and Mab, out of scale). Neptune: Naiad, Thalassa, Despina, Galatea, Larissa, and Proteus. Jupiter: Metis, Adrastea, Amalthea, These, Io, Europa, Ganymede, and Callisto. (A) Mass as a function of the orbital radius. The four systems do not extend all the way down to the planetary radius (vertical line), but a pile-up of small satellites is observed at a specific distance (the Roche limit, rR ). The mass increases from zero with the distance to rR , not to the center of the planets. (B) Satellite-to-planet mass ratio q as a function of D = (r – rR )/rR . The Roche radius for each planet is taken consistently with the mean density of satellites, or with the orbit of the closest one (SM 1). For Saturn, Uranus, and Neptune, rR = 140,000, 57,300, and 44,000 km, respectively. Short dashed curves: our model for the pyramidal regime Q(D) (eq. S25, SM 6.3): for D < D2:1 , q º D9/5 ; for D > D2:1 , q º (D + 1)3.9, where D2:1 = 0.59 is marked by the vertical dashed line. Jupiter’s system does not fit well and is not shown (SM 7.3). Fig. 2. Sketches of the three accretion regimes, where the accretion re- gions are defined as T2rH REPORTS [Crida & Charnoz, Science, 2012] Ϧϯά͔Βશͯͷڊେ࿭੕ͷنଇӴ੕ܥ͕ܗ੒ γφϦΦఏҊͷΈͰ਺஋ܭࢉʹΑΔݕূ͸΄΅ແ͍ Ϧϯά͔ΒͷنଇӴ੕ܗ੒
9. ༷ʑͳӴ੕ܗ੒࿦ • δϟΠΞϯτΠϯύΫτʢ݄ɾΧϩϯʣ • प࿭੕ԁ൫ʢΨϦϨΦӴ੕ɾλΠλϯʣ • Ϧϯάʢڊେ࿭੕ͷنଇӴ੕ͷҰ෦ʣ • ั֫ʢڊେ࿭੕ͷෆنଇӴ੕ɾτϦτϯʣ • ະ֬ఆʢՐ੕Ӵ੕ɾఱԦ੕Ӵ੕ʣ • ଠཅܥ֎ͷӴ੕ܗ੒࿦ʹ޲͚ͯ
10. ଠཅܥͷ୅දతͳӴ੕ͨͪ (c) Wikipedia
11. (c) Roberto Molar-Candanosa, courtesy of Carnegie Institution for Science ໦੕ͷෆنଇӴ੕
12. Ψε࿭੕ͷෆنଇӴ੕ͷيಓ ٯߦӴ੕ ໦੕ͷෆنଇӴ੕ ॱߦӴ੕ نଇӴ੕ Ψε࿭੕ͷيಓ܏ࣼ֯ يಓ൒ܘ͕େ͖͍ ˍ ܏͍ͨପԁيಓͷ΋ͷ͕ଟ͍
13. Ψε࿭੕ͷෆنଇӴ੕ͷั֫ ɾप࿭੕ԁ൫ͷΨε఍߅ʹΑͬͯඍ࿭੕Λั֫ ɹɹ̋ΤωϧΪʔతʹ͸ั͕֫Մೳ ɹɹ̋ٯߦͷํ͕ΤωϧΪʔࢄҳ͕େ͖͘ั͕֫༰қ ɹɹ˚ଟ͘ͷӴ੕͸Ψε఍߅ʹΑͬͯམԼ͢Δ [Pollack et al., Icarus, 1979] ɾ࿭੕ಉ͕࢜઀ۙͨ͠ࡍʹࢄཚ͞Εͨඍ࿭੕Λั֫ ɹɹ̋ݱࡏ؍ଌ͞Ε͍ͯΔӴ੕يಓ෼෍ΛΑ͘࠶ݱ ɹɹ˚࿭੕ܗ੒ͷϞσϧʹ݁Ռ͕ڧ͘ґଘ͢Δ [Nesvorný et al., AJ, 2014]
14. ଠཅܥͷ୅දతͳӴ੕ͨͪ (c) Wikipedia
15. [Agnor & Hamilton, Nature, 2006] ւԦ੕ͷӴ੕τϦτϯͷั֫ τϦτϯ͸όΠφϦఱମͷยํͷΈ͕ั֫͞Εͨ΋ͷ ࡾମ૬ޓ࡞༻ىݯͷෆنଇӴ੕͸ଞʹ΋͋ΓಘΔ ւԦ੕ͷӴ੕ͷ࣭ྔׂ߹
16. ༷ʑͳӴ੕ܗ੒࿦ • δϟΠΞϯτΠϯύΫτʢ݄ɾΧϩϯʣ • प࿭੕ԁ൫ʢΨϦϨΦӴ੕ɾλΠλϯʣ • Ϧϯάʢڊେ࿭੕ͷنଇӴ੕ͷҰ෦ʣ • ั֫ʢڊେ࿭੕ͷෆنଇӴ੕ɾτϦτϯʣ • ະ֬ఆʢՐ੕Ӵ੕ɾఱԦ੕Ӵ੕ʣ • ଠཅܥ֎ͷӴ੕ܗ੒࿦ʹ޲͚ͯ
17. ଠཅܥͷ୅දతͳӴ੕ͨͪ (c) Wikipedia
18. Ր੕ͷӴ੕ɿϑΥϘεͱμΠϞε ɾද໘ͷ൓ࣹεϖΫτϧ͸ D ܕখ࿭੕ʹࣅ͍ͯΔ ɹɹˠ খ࿭੕ଳ͔Β΍͖ͬͯͨఱମͷั֫ʁ ɾՐ੕ͷ੺ಓ໘Λ΄΅ԁيಓͰճ͍ͬͯΔ ɹɹˠ ఱମিಥʹΑΔഁยͷूੵͰܗ੒ʁ (c) Wikipedia [Hunten, Icarus, 1979; Burns, “Mars”, 1992] [Craddock, Icarus, 2011; Rosenblatt et al., Nature Geoscience, 2016 ]
19. NATURE GEOSCIENCE DOI: 10.1038/NGEO2742 3:2 2:1 Migration of the largest inner moon 0 2 4 6 Time since formation of the largest inner moon (kyr) 8 3 4 5 Semimajor axis (R Mars ) 6 7 Figure 3 | Typical evolution of the outer disc since the inner moon’s formation, resulting in satellites similar to Phobos and Deimos. Satellite embryos of mass ⇠1% that of Phobos are initially between 4.4 and 7 Mars radii. The thick line represents the outward migration of the inner moon from the Roche limit. The thin lines are the positions of MMRs following the migration. The size of the circles is proportional to the mass of the body. Received 18 January published online 4 J References 1. Burns, J. in Mars (ed & Matthews, M. S.) 1 2. Peale, S. J. in Treatise 465–508 (Elsevier B. 3. Rosenblatt, P. The or Rev. 19, 44 (2011). 4. Safranov, V. S. et al. i (Univ. Press of Arizo 5. Citron, R. I., Genda, impact. Icarus 252, 3 6. Craddock, R. A. Are 211, 1150–1161 (201 7. Rosenblatt, P. & Cha circum-martian accr 8. Charnoz, S., Salmon, from viscous spreadi 9. Charnoz, S. et al. Acc spreading of young m silicate-rich moons. I 10. Marinova, M. M., Ah planetary-scale impa [Rosenblatt et al., Nature Geo., 2016] Giant Impact ʹΑΔӴ੕ܗ੒ Ր੕΁ͷ Giant Impact ͰͰ͖ͨԁ൫͔ΒͷӴ੕ܗ੒ ϑΥϘεΑΓ಺ଆʹҰ࣌తʹڊେӴ੕ͷଘࡏ͕ඞཁ Phobos Deimos ڞճస൒ܘ
20. NATURE GEOSCIENCE DOI: 10.1038/NGEO2916 ARTICLES (Mars radii) 1 2 RRL a FRL Synch. RRL FRL Synch. RRL FRL Synch. RRL FRL Synch. RRL FRL Synch. RRL FRL Synch. 3 4 5 6 7 1 2 3 4 5 6 7 1 2 3 4 5 6 7 1 2 3 4 5 6 7 1 2 3 4 5 6 7 1 2 3 4 5 6 7 b c d e f system that preceded Phobos was approximately five times as massive as Phobos, and the satellite/ring system that preceded it was approximately five times larger still (see Fig. 1). The above mass estimates are determined by the location where satellite breakup occurs, which we took to be at the RRL, located at ⇠1.6RM (see Supplementary Methods). However, breakup of the Martian satellites, which are probably undi erentiated gravitational aggregates, could occur between 1.2 and 1.7RM , depending on their cohesive strength16,19. We found that if satellite breakup occurred at 1.2RM , only ⇠6% of the ring mass accretes into new satellites during each subsequent cycle, whereas if breakup occurred at 1.7RM , then ⇠25% of the ring mass accretes into new satellites (see Supplementary Fig. 4). Because this breakup location is the largest source of uncertainty in the per-cycle mass loss estimates in our model, we define our ‘nominal case’ as the one where breakup occurs at the RRL at ⇠1.6RM , and use the estimated limits of the satellite breakup location to determine the uncertainty in our results. Phobos produced from series of satellite–ring cycles We will from here on refer to the most recent cycle, which produced present-day Phobos, as ‘Cycle 1’, and then count upwards in reverse chronological order. Beginning with Phobos, in Table 1 we calculate the system mass for each previous cycle until we reach an initial ring mass that is greater than what would be expected to form out of the dichotomy-forming impact ejecta. We find that a ring with any of the initial masses listed in Table 1 will eventually form Phobos. However, only giant impacts, in which the gravitational field of the planet is significantly distorted during the debris ejection process, are able to place ejected material into stable orbits, thus ruling out low-mass cycles as possible starting points. We used the most massive cycle in Table 1 to set the initial conditions for RING-MOONS. We assume that the dichotomy- forming impact formed both Deimos and a ring with a mass of 1.2+0.5 0.7 ⇥ 1023g. Although we find that rings composed of smaller particles take longer to complete a cycle than rings composed of larger particles, the mass ratio between the initial ring mass and the total mass of the satellites produced remained constant, independent of ring particle size. We conducted multiple simulations of all cycles, Ϧϯά͔Βͷ ܁Γฦ͠Ӵ੕ܗ੒ Ր੕ͷ಺ଆͷӴ੕ϑΥϘε͸ ɾϦϯά͔Βͷܗ੒ ɾைࣚʹΑΔՐ੕΁ͷམԼ ɾைࣚഁյͱϦϯάܗ੒ Λ܁Γฦ͍ͯ͠Δ [Hesselbrock & Minton, Nature Geo., 2017] ΞΠσΞͷΈɾ਺஋ܭࢉແ͠ ࠷ޙ͸ܗ੒ʹ25ԯ೥͔͔Δ...
21. Ր੕Ӵ੕αϯϓϧϦλʔϯ Ր੕Ӵ੕ͷىݯ ʢั֫ or িಥʣ 
 ʹܾணΛ͚ͭΔ Two Leading Hypothesis MMX is a JAXA’s sample return mission to Martian moons Primary goal of MMX mission is to solve moons’ origin capture origin capture impact disk giant impact origin Two Leading Hypothesis MMX is a JAXA’s sample return mission to Martian moons Primary goal of MMX mission is to solve moons’ origin capture origin capture impact disk giant impact origin
22. ଠཅܥͷ୅දతͳӴ੕ͨͪ (c) Wikipedia
23. ԣ౗͠ͷఱԦ੕Ӵ੕ܥ ɾఱԦ੕͸ࣗస͕࣠98౓܏͍͍ͯΔ ɾఱԦ੕ͷ̑େӴ੕΋ಉ༷ʹ܏͍ͯ ɹճ͍ͬͯΔ
24. Figure 3 | Properties of observed satellites compared to simulations. Panel a shows observed satellites, while panels b and c contain final simulated systems produced by time-dependent inflows (with mS , satellite mass; MP planetary mass). Panels b and c show results of inflows with gin ¼ 0, rC ¼ 30RP , 1:7 , Min =MT , 10 (where Min is the total mass in solids delivered to the disk), and inflow exponential decay times, tin , between 2 £ 105 yr and 1.5 £ 106 yr. Systems were simulated for between 3 £ 106 yr and 107 yr. Similar results are expected for higher Min /MT values (corresponding to longer decay times and/or higher initial inflow rates), (a/f) ¼ 1026 case, with ðMT =MP Þ ¼ 6:6 £ 1025 ( a ¼ 0.0065 produces a g (c20, red), while an ða=f uranian-like system with system with (MT /MP ) ¼ and a ¼ 0.006. The mos and 70% of the total sate satellite at 11.3RP (with C NATURE|Vol 441|15 June 2006 प࿭੕ԁ൫͔ΒఱԦ੕Ӵ੕ܥʹࣅͨܥ͕ܗ੒ େྔͷ N ମܭࢉʹΑΔ “෼ࢄ” ͷ݁Ռʹ͗͢ͳ͍ ఱԦ੕Ӵ੕ܥͷ܏͖͸આ໌͕೉͍͠ [Canup & Ward, Nature, 2006] प࿭੕ԁ൫͔ΒͷӴ੕ܗ੒
25. ~100 orbits. Also, qd < 0.1D provided D < 6.7 × 10−3. This is always the case around giant plan- ets (see below and SM 7), and it justifies the assumption that D and tdisk are constant. After Dd is reached, a third moon appears in the sys- Fig. 1. Distribution of the regular satellites of the giant planets. Saturn: 9 satellites from Pandora to Titan. Uranus: (A) 18 from Cordelia to Oberon; (B) 14 satellites, from Bianca to Oberon (except Cupid and Mab, out of scale). Neptune: Naiad, Thalassa, Despina, Galatea, Larissa, and Proteus. Jupiter: Metis, Adrastea, Amalthea, These, Io, Europa, Ganymede, and Callisto. (A) Mass as a function of the orbital radius. The four systems do not extend all the way down to the planetary radius (vertical line), but a pile-up of small satellites is observed at a specific distance (the Roche limit, rR ). The mass increases from zero with the distance to rR , not to the center of the planets. (B) Satellite-to-planet mass ratio q as a function of D = (r – rR )/rR . The Roche radius for each planet is taken consistently with the mean density of satellites, or with the orbit of the closest one (SM 1). For Saturn, Uranus, and Neptune, rR = 140,000, 57,300, and 44,000 km, respectively. Short dashed curves: our model for the pyramidal regime Q(D) (eq. S25, SM 6.3): for D < D2:1 , q º D9/5 ; for D > D2:1 , q º (D + 1)3.9, where D2:1 = 0.59 is marked by the vertical dashed line. Jupiter’s system does not fit well and is not shown (SM 7.3). Fig. 2. Sketches of the three accretion regimes, where the accretion re- gions are defined as T2rH around a moon’s location. REPORTS [Crida & Charnoz, Science, 2012] Ϧϯά͔ΒͷӴ੕ܗ੒ Ϧϯά͔Βͷܗ੒ͰఱԦ੕Ӵ੕ܥʹࣅͨ෼෍͕࠶ݱ ఱԦ੕ͷ̐େӴ੕͸໌Β͔ʹ༧ଌ͔ΒͣΕ͍ͯΔ 
 ఱԦ੕Ӵ੕ܥͷ܏͖ʹ͸ผͷաఔ͕ඞཁ
26. Giant Impact ʹΑΓఱԦ੕ܥͷ܏͖Λઆ໌ ܏͍ͨఱԦ੕पғͷিಥഁยԁ൫͔ΒӴ੕͕ܗ੒ ਺஋ܭࢉʹΑΔݕূ͕े෼ʹߦΘΕ͍ͯͳ͔ͬͨ [Ishizawa, Sasaki & Hosono, ApJ, 2019] Giant Impact ʹΑΔӴ੕ܗ੒ Saturn, given by the tidal quality factor Qp =1680, and plied this value to the other planets (see Section 4). do et al. (2015) performed direct numerical simulations lite formation in the disks modeled by Crida & Charnoz to investigate a more realistic dynamical effect on the on and orbital evolution of satellites. They confirmed east 1–2 satellites are formed from the disks. The origin al disk is not explicit; however, they suggest that a tidal The present study adopts the giant impact scenari possible process for the formation of Uranian regular sat We model a wide disk around Uranus and investigate the formation of the Uranian regular satellites using N simulations. 2. Calculation Method We considered a model in which satellites grow w . Schematic of satellite formation in the giant impact scenario. First, two protoplanets collide with each other and the materials of these two bodies are satellites form from the circumplanetary disk of ejected materials. rophysical Journal, 885:132 (10pp), 2019 November 10 Ishizawa, Sasaki, &
27. Giant Impact ௚ޙͷিಥഁย෼෍Λ΋ͱʹͯ͠ Ӵ੕ܗ੒աఔʹ͍ͭͯͷ N ମܭࢉΛߦͬͨ ࣮ࡍͷӴ੕࣭ྔɾيಓ෼෍Λ࠶ݱͰ͖ͳ͔ͬͨ [Ishizawa, Sasaki & Hosono, ApJ, 2019] ఱԦ੕Ӵ੕ܗ੒ N ମܭࢉ shizawa et al. 2019  "
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28. Giant Impact ௚ޙ͸িಥഁย͸΄΅ৠൃ͍ͯ͠Δ ɹˠ ԁ൫ͷྫྷ٫ਐԽաఔΛߟ͑Δඞཁ͕͋Δʂ [Ida, Ueta, Sasaki & Ishizawa, Nature Astronomy, 2020] ԁ൫ਐԽաఔΛߟྀ͢΂͠ Protoplanets collide each other Satellite formation Giant Impact (GI) scenario for satellite formation Disk evolution • A disk generated by a giant impact is mostly vaporized • It may undergo viscous diffusion until the re-condensation of materials SPH method N-body In hydrodynamical simulations it is difficult to describe dynamics of such disk including phase change over several hundred years
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    TJEF
    Giant Impact ௚ޙ͸෯ڱͰް͘ ಺ଆʹ෺࣭͕ଟ͍෼෍ ࠷ऴతʹ͸෯޿Ͱബ͘ ֎ଆʹ෺࣭͕ଟ͍෼෍ ԁ൫ͷ֦ࢄͱ ྫྷ٫ʹΑΔݻԽ
30. ৽͍͠ԁ൫෺࣭෼෍ʹج͍ͮͨ N ମܭࢉʹΑΓ ఱԦ੕Ӵ੕ܥͷ࣭ྔɾيಓ෼෍Λ΄΅࠶ݱ [Ida, Ueta, Sasaki & Ishizawa, Nature Astronomy, 2020] ఱԦ੕Ӵ੕ܥͷ࠶ݱʹ੒ޭ
31. ༷ʑͳӴ੕ܗ੒࿦ • δϟΠΞϯτΠϯύΫτʢ݄ɾΧϩϯʣ • प࿭੕ԁ൫ʢΨϦϨΦӴ੕ɾλΠλϯʣ • Ϧϯάʢڊେ࿭੕ͷنଇӴ੕ͷҰ෦ʣ • ั֫ʢڊେ࿭੕ͷෆنଇӴ੕ɾτϦτϯʣ • ະ֬ఆʢՐ੕Ӵ੕ɾఱԦ੕Ӵ੕ʣ • ଠཅܥ֎ͷӴ੕ܗ੒࿦ʹ޲͚ͯ
32. .BZPS
    
    2VFMP[
    εΠεͷ؍ଌνʔϜ
    ϖΨαε࠲൪੕ͷपΓʹ
    )PU
    +VQJUFS
    ͕ଘࡏʂ ೥݄ ਓྨॳͷܥ֎࿭੕ൃݟ (c) NASA (c) Michel Mayor
33. ೥ϊʔϕϧ෺ཧֶ৆ड৆
34. ଠཅܥ֎࿭੕͕ଓʑͱݟ͔ͭΔ ೥݄೔ݱࡏ
     ݸͷܥ֎࿭੕͕֬ೝ
35. (c) NASA [Teachey & Kipping, Science Advances, 2018] ܥ֎Ӵ੕ީิ Kepler-1625b-i 2018೥10݄ɿܥ֎࿭੕ Kepler-1625b ͷपΓʹ্࢙ॳ ͷܥ֎Ӵ੕ީิఱମͷݕग़͕ใࠂ͞Εͨ 2021೥ଧ্ͪ͛༧ఆͷ JWST ʹΑΔ؍ଌͰ֬ఆ༧ఆ ʢδΣΠϜζɾ΢ΣοϒӉ஦๬ԕڸʣ
36. • ܥ֎Ψε࿭੕पΓͷӴ੕ܗ੒ͱϋϏλϏϦςΟ
 • ܥ֎εʔύʔ໦੕पΓͷڊେӴ੕ܗ੒
 • Giant Impact ʹΑΔܥ֎Ӵ੕ܗ੒
 • ܥ֎࿭੕ͱͦͷपΓͷӴ੕ͷϋϏλϏϦςΟ
 • ܥ֎ණӴ੕ͷ಺෦ւͷϋϏλϏϦςΟ NASA ܥ֎Ӵ੕ʹؔ͢Δݚڀ [Heller,…, Sasaki et al., Astrobiology, 2014] [Yamanaka, Shibaike & Sasaki, under investigation] [Hasegawa, Hosono & Sasaki, under investigation] [Yamashiki,…, Sasaki et al., ApJ, 2019] [Ueta & Sasaki, ApJ, 2013]
37. • ܥ֎Ψε࿭੕पΓͷӴ੕ܗ੒ͱϋϏλϏϦςΟ
 • ܥ֎εʔύʔ໦੕पΓͷڊେӴ੕ܗ੒
 • Giant Impact ʹΑΔܥ֎Ӵ੕ܗ੒
 • ܥ֎࿭੕ͱͦͷपΓͷӴ੕ͷϋϏλϏϦςΟ
 • ܥ֎ණӴ੕ͷ಺෦ւͷϋϏλϏϦςΟ NASA ܥ֎Ӵ੕ʹؔ͢Δݚڀ [Heller,…, Sasaki et al., Astrobiology, 2014] [Yamanaka, Shibaike & Sasaki, under investigation] [Hasegawa, Hosono & Sasaki, under investigation] [Yamashiki,…, Sasaki et al., ApJ, 2019] [Ueta & Sasaki, ApJ, 2013]
38. NASA εʔύʔ໦੕पΓͷӴ੕ܗ੒ [Heller,…, Sasaki et al., Astrobiology, 2014] ໦੕ͷ10ഒͷ࣭ྔͷΨε࿭੕पΓɿ ɹΨϦϨΦӴ੕ʢ4ݸʣͱಉ͔ͦ͡ΕҎ্ͷݸ਺ ɹՐ੕ఔ౓ͷ࣭ྔͷڊେӴ੕͕ܗ੒͞ΕΔՄೳੑ
39. • ܥ֎Ψε࿭੕पΓͷӴ੕ܗ੒ͱϋϏλϏϦςΟ
 • ܥ֎εʔύʔ໦੕पΓͷڊେӴ੕ܗ੒
 • Giant Impact ʹΑΔܥ֎Ӵ੕ܗ੒
 • ܥ֎࿭੕ͱͦͷपΓͷӴ੕ͷϋϏλϏϦςΟ
 • ܥ֎ණӴ੕ͷ಺෦ւͷϋϏλϏϦςΟ NASA ܥ֎Ӵ੕ʹؔ͢Δݚڀ [Heller,…, Sasaki et al., Astrobiology, 2014] [Yamanaka, Shibaike & Sasaki, under investigation] [Hasegawa, Hosono & Sasaki, under investigation] [Yamashiki,…, Sasaki et al., ApJ, 2019] [Ueta & Sasaki, ApJ, 2013]
40. NASA Giant Impact ʹΑΔܥ֎Ӵ੕ܗ੒ ଟ༷ͳڊେিಥ ଟ༷ͳԁ൫৚݅ ଟ༷ͳӴ੕ܗ੒ [Hasegawa, Hosono & Sasaki, under investigation]
41. • ܥ֎Ψε࿭੕पΓͷӴ੕ܗ੒ͱϋϏλϏϦςΟ
 • ܥ֎εʔύʔ໦੕पΓͷڊେӴ੕ܗ੒
 • Giant Impact ʹΑΔܥ֎Ӵ੕ܗ੒
 • ܥ֎࿭੕ͱͦͷपΓͷӴ੕ͷϋϏλϏϦςΟ
 • ܥ֎ණӴ੕ͷ಺෦ւͷϋϏλϏϦςΟ NASA ܥ֎Ӵ੕ʹؔ͢Δݚڀ [Heller,…, Sasaki et al., Astrobiology, 2014] [Yamanaka, Shibaike & Sasaki, under investigation] [Hasegawa, Hosono & Sasaki, under investigation] [Yamashiki,…, Sasaki et al., ApJ, 2019] [Ueta & Sasaki, ApJ, 2013]
42. ͳ͢ɻ࿭੕ͷݻମ෦෼ͷද໘Թ౓ T ͸ҎԼͷΑ͏ʹਫͷް͞ dw ʹΑܾͬͯ ༷ʑͳւʢ಺෦ւʣͷ૚ߏ଄
43. Distance from the Central Star
    10
    1
    0.1
    Planetary Mass (M/M E )
    Distance from the Central Star (AU)
    
    0
    40
    20
    ①: Only Ice I ②: Internal Ocean ③: Ocean on the Surface ⑤: High- pressure Ice under Internal Ocean 1, 2, 5, 10
    E/E E = 1
    M sw /M swE =
    Internal ocean without high-pressure ice layers The strong constraints on the planetary mass and H 2 O mass ①
    ②
    ③
    
    ⑤
    த৺੕͔Βͷڑ཭ʢAUʣ ࿭੕ͷ࣭ྔʢME ʣ ༷ʑͳ࿭੕ͷւʢ಺෦ւʣͷߏ଄ ࿭੕ද໘ͷਫͷ࠷ਂ෦ͷѹྗ p (bar) ͸ҎԼͷΑ͏ʹදͤΔɻ p = dwρwg × 10−5 (3.22) ϞσϧΛ؆ུԽ͢ΔͨΊʹɺණ 1-ӷମͷڥքʹ͓͚Δ༥఺ۂઢΛ௚ઢͱΈ ͳ͢ɻ࿭੕ͷݻମ෦෼ͷද໘Թ౓ T ͸ҎԼͷΑ͏ʹਫͷް͞ dw ʹΑܾͬͯ ਤ 3.5: ࿭੕ද໘ʹਫ͕͋Δ৔߹ͷද໘ঢ়ଶͷ෼ྨ: λΠϓ 1,4 ͸ද໘͕ණͷ Έͱͳ͍ͬͯΔ৔߹ͰɺλΠϓ 4 ͸ණͷఈͷ෦෼ʹߴѹණ͕ଘࡏ͢ΔɻλΠ ϓ 2 ͸಺෦ւ͕ଘࡏ͢Δ৔߹ͰϋϏλϒϧͳՄೳੑ͕͋ΔɻλΠϓ 5 ͸಺෦ ւ͕ଘࡏ͢Δ͕಺෦ւͷఈ͕ߴѹණͱͳ͓ͬͯΓɺϋϏλϒϧͱ͸ݴ͑ͳ͍ ͩΖ͏ɻλΠϓ 3,6 ͸࿭੕ද໘Թ౓͕ 273K ΑΓ΋େ͖͘ͳΓɺද໘ʹණ͕ଘ ࡏ͠ͳ͍৔߹Ͱ͋Δ (ւ࿭੕)ɻୠ͠ւͷਂ౓͕େ͖͍৔߹ɺλΠϓ 6 ͷΑ͏ ʹఈʹߴѹණ͕ग़དྷͯ͠·͏ɻ 19 [Ueta & Sasaki 2013] ϋϏλϒϧͳՄೳੑͷ͋Δ಺෦ւ ᶄ Λ΋ͭ৚݅͸ ࿭੕ͷ࣭ྔʹରͯ͠ඇৗʹݫ੍͍͠ݶ͕͋Δ
44. ༷ʑͳӴ੕ܗ੒࿦ • δϟΠΞϯτΠϯύΫτʢ݄ɾΧϩϯʣ • प࿭੕ԁ൫ʢΨϦϨΦӴ੕ɾλΠλϯʣ • Ϧϯάʢڊେ࿭੕ͷنଇӴ੕ͷҰ෦ʣ • ั֫ʢڊେ࿭੕ͷෆنଇӴ੕ɾτϦτϯʣ • ະ֬ఆʢՐ੕Ӵ੕ɾఱԦ੕Ӵ੕ʣ • ଠཅܥ֎ͷӴ੕ܗ੒࿦ʹ޲͚ͯ