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宇宙科学入門(2020年度後期)

 宇宙科学入門(2020年度後期)

学部生向け教養講義である宇宙科学入門で、惑星形成論に関する話をしてきました。そのときの講義資料です。

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Takanori Sasaki

November 04, 2020
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  1. 2020೥11݄4೔ɹӉ஦Պֶೖ໳ 2020೥౓ޙظ@Zoom ࿭੕ܥͷܗ੒ཧ࿦ େֶӃཧֶݚڀՊ Ӊ஦෺ཧֶڭࣨɹࠤʑ໦وڭ

  2. ߨٛͷ಺༰ ✤ ݱࡏͷଠཅܥͷ࢟ ɹ8ͭͷ࿭੕ͱͦͷӴ੕ɺແ਺ͷখఱମͨͪ ✤ ଠཅܥܗ੒࿦ͷϨϏϡʔ ɹඪ४ཧ࿦ʢژ౎Ϟσϧʣͷ֓ཁͱͦͷ֦ு ✤ ܥ֎࿭੕ͷൃݟɺͦͯ͠൚࿭੕ܗ੒ཧ࿦΁ ɹଟछଟ༷ͳҟܗͷ࿭੕ͨͪͷ࡞Γํ

  3. ଠཅܥͷߏ੒ϝϯόʔ ஍ٿܕ࿭੕ ɹɹਫ੕ ɹɹۚ੕ ɹɹ஍ٿ ɹɹՐ੕ ڊେΨε࿭੕ ɹɹɹ໦੕ ɹɹɹ౔੕ ڊେණ࿭੕

    ɹɹఱԦ੕ ɹɹւԦ੕ খఱମʢখ࿭੕ ଠཅܥ֎ԑఱମ ΦʔϧτͷӢʣ (c) ikachi.org
  4. ֤ఱମͷيಓ (c) wakatsuki

  5. ਫ੕ ۚ੕ ஍ٿ Ր੕ يಓ௕൒ܘ [AU] 0.39 0.72 1 1.52

    ެసपظ [೥] 0.241 0.615 1 1.881 ࣭ྔ [஍ٿ = 1] 0.055 0.82 1 0.11 ൒ܘ [km] 2440 6052 6378 3396 ີ౓ [kg/m3] 5430 5240 5520 3930 Ӵ੕ͷ਺ 0 0 1 2 ஍ٿܕ࿭੕ͷੑ࣭
  6. ໦੕ ౔੕ ఱԦ੕ ւԦ੕ يಓ௕൒ܘ [AU] 5.2 9.6 19.2 30.1

    ެసपظ [೥] 11.86 29.46 84.02 164.7 ࣭ྔ [஍ٿ = 1] 317.8 95.2 14.5 17.2 ൒ܘ [km] 71490 60270 25560 24760 ີ౓ [kg/m3] 1330 690 1270 1640 Ӵ੕ͷ਺ 49 53 27 13 ڊେΨε࿭੕ɾණ࿭੕ͷੑ࣭
  7. ஍ٿܕ࿭੕ͷ಺෦ߏ଄ ਫ੕ ஍֪ Ϛϯτϧ ίΞ Ր੕ ஍ٿ ݄ ۚ੕ ݻମͷ಺֩

    ӷମͷ֎֩ ίΞʁ (c) Wikipedia
  8. ڊେΨε࿭੕ɾණ࿭੕ͷ಺෦ߏ଄ ໦੕ ౔੕ ఱԦ੕ ւԦ੕ ஍ٿ ਫૉ෼ࢠ ۚଐਫૉ ਫૉɾϔϦ΢ϜɾϝλϯΨε ϚϯτϧʢਫɾΞϯϞχΞɾϝλϯණʣ

    ίΞʢؠੴɾණʣ (c) Wikipedia
  9. ଠཅܥܗ੒ඪ४ཧ࿦ʢژ౎Ϟσϧʣ         

       ©Newton Press ڊେණ࿭੕ܗ੒
  10. ژ౎Ϟσϧͷجຊ֓೦ ԁ൫Ծઆ ɾ࿭੕ܥ͸ݪ࢝࿭੕ܥԁ൫͔Βܗ੒͞ΕΔ ɾԁ൫͸ͷΨεͱͷμετ͔Βߏ੒͞ΕΔ ඍ࿭੕Ծઆ ɾμετͷूੵʹΑͬͯඍ࿭੕͕ܗ੒͞ΕΔ ɾඍ࿭੕ͷूੵʹΑͬͯݻମ࿭੕͕ܗ੒͞ΕΔ ɾݻମ࿭੕ʹΨε͕߱Γੵ΋Δ͜ͱʹΑͬͯ ɹΨε࿭੕͕ܗ੒͞ΕΔ ɹɹɹɹɹɹɹɹɹɹɹɹ<ྛ஧࢛࿠ଞ

    >
  11. ෼ࢠӢ͔Βݪ࢝੕ˍݪ࢝࿭੕ܥԁ൫΁ (c) Yusuke Tsukamoto ʢ̍ʣ੕ؒ෼ࢠӢͷऩॖͱίΞͷܗ੒ ʢ̎ʣݪ࢝੕ͷܗ੒ͱ੒௕ ʢ̏ʣओܥྻ੕ͱݪ࢝࿭੕ܥԁ൫ͷܗ੒ ੕ܗ੒ͷ ̏ஈ֊

  12. ݪ࢝࿭੕ܥԁ൫ͷ؍ଌ ࣮ࡍʹ༷ʑͳܗͷԁ൫͕؍ଌ͞Ε͍ͯΔ ɹˠݪ࢝࿭੕ܥԁ൫͸͔֬ʹଘࡏ͢Δʂ (c) SUBARU (c) SUBARU (c) ALMA

  13. ඍ࿭੕ܗ੒γφϦΦͱ༷ʑͳࠔ೉ μετ(≲µm) ࿭੕(≳103km) ݪ࢝࿭੕ܥԁ൫ ඍ࿭੕(≳km) ࿭੕ܗ੒ͱඍ࿭੕ܗ੒ !5 ice +rock ice+rock

    rock Itokawa (~0.5km) rock ॏྗूੵ ෼ࢠؒྗूੵ + μετ૚ͷࣗݾ ॏྗෆ҆ఆ? εϊʔϥΠϯ (~1-3AU?) ௚઀߹ମ੒௕ μετͷࣗݾॏྗෆ҆ఆ μετ ඍ࿭੕ ЖN NN N LN ੩ి൓ൃোน ௓ͶฦΓোน த৺੕མԼোน িಥഁյোน ཚྲྀোน ☓☓ ☓ ☓☓
  14. ඍ࿭੕ͷ߹ମ੒௕ ਺LNαΠζͷ ඍ࿭੕͕ܗ੒ ޓ͍ʹিಥɾ߹ମ Λ܁Γฦ͠੒௕ ˣ ๫૸త੒௕ ɹେཻ͖͍ࢠ΄Ͳ੒௕͕଎͍ டংత੒௕ ɹશͯͷཻࢠ͕ಉ͡଎౓Ͱ੒௕

    (c) Kouji KANBA
  15. ଟମ໰୊ઐ༻ܭࢉػ(3"1& ଟମʢඍ࿭੕ʣͷॏྗܭࢉ ɹˠܭࢉྔ͕๲େʹͳΔ ཻࢠؒ૬ޓ࡞༻ͷ෦෼͚ͩΛ ઐ༻ܭࢉػͰܭࢉ͍ͨ͠ ɹˠ(3"1&஀ੜʂ (3"1&ͱ຀໺३Ұ࿠ڭत (c) Junichiro Makino

  16. KOKUBO AND IDA FIG. 4. Time evolution of the maximum

    mass (solid curve) and the mean mass (dashed curve) of the system. thanthisrangearenotstatisticallyvalidsinceeachmassbinoften has only a few bodies. First, the distribution tends to relax to a ๫૸త੒௕ͷ༷ࢠ ฏۉ஋ ࠷େͷఱମ ඍ࿭੕ͷ๫૸త੒௕ ɹˠݪ࢝࿭੕͕஀ੜ͢Δ 20 KOKUBO AND IDA FIG. 3. Snapshots of a planetesimal system on the a–e plane. The circles represent planetesimals and their radii are proportional to the radii of planetesi- mals. The system initially consists of 3000 equal-mass (1023 g) planetesimals. FIG. 4. Time evolution of the maximum mass (solid curve) and the mean mass (dashed curve) of the system. thanthisrangearenotstatisticallyvalidsinceeachmassbinoften has only a few bodies. First, the distribution tends to relax to a decreasing function of mass through dynamical friction among (energy equipartition of) bodies (t = 50,000, 100,000 years). Second, the distributions tend to flatten (t = 200,000 years). This is because as a runaway body grows, the system is mainly heated by the runaway body (Ida and Makino 1993). In this case, the eccentricity and inclination of planetesimals are scaled by the يಓ௕൒ܘ<"6> يಓ཭৺཰ ࣭ྔ<H> ࣌ؒ<೥> <,PLVCP*EB >
  17. Չ઎త੒௕ͷ༷ࢠ FORMATION OF PROTOPLANETS FROM PLANETESIMALS 23 FIG. 7. Snapshots

    of a planetesimal system on the a–e plane. The cir- cles represent planetesimals and their radii are proportional to the radii of planetesimals. The system initially consists of 4000 planetesimals whose to- tal mass is 1.3 × 1027 g. The initial mass distribution is given by the power- FIG. 8. The number of bodies in linear mass bins is plotted for t = 100,000, 200,000, 300,000, 400,000, and 500,000 years. In Fig. 10, we plot the maximum mass and the mean mass of يಓ཭৺཰ ֤৔ॴͰඍ࿭੕͕๫૸త੒௕ ɹˠ౳αΠζͷݪ࢝࿭੕͕ฒͿ Չ઎త੒௕ͱΑͿ ʹ ֤يಓͰͷݪ࢝࿭੕ ࣭ྔ [kg] ܗ੒࣌ؒ [yr] ஍ٿيಓ 1×1024 7×105 ໦੕يಓ 3×1025 4×107 ఱԦ੕يಓ 8×1025 2×109 يಓ௕൒ܘ<"6> <,PLVCP*EB >
  18. ݪ࢝࿭੕͔Β࿭੕΁ )-/    2  .3 ( )

    -/(% -/ ) 0  #    " 4+ ݪ࢝࿭੕ͷ࣭ྔ<஍ٿ࣭ྔ> يಓ௕൒ܘ<"6> ஍ٿܕ࿭੕ ɹݪ࢝࿭੕ಉ࢜ͷ߹ମ ڊେΨε࿭੕ ɹݪ࢝࿭੕ͷΨεั֫ ڊେණ࿭੕ ɹݪ࢝࿭੕ͦͷ·· TOPXMJOF (c) Eiichiro Kokubo
  19. δϟΠΞϯτΠϯύΫτ ݪ࢝࿭੕ಉ࢜ͷڊେఱମিಥΛ܁Γฦ͠ ݱࡏͷ࿭੕΁ (c) NASA

  20. δϟΠΞϯτΠϯύΫτ يಓ௕൒ܘ<"6> يಓ཭৺཰ planets is hnM i ’ 2:0 Æ

    0:6, which means that the typical result- ing system consists of two Earth-sized planets and a smaller planet. In this model, we obtain hna i ’ 1:8 Æ 0:7. In other words, one or two planets tend to form outside the initial distribution of protoplanets. In most runs, these planets are smaller scattered planets. Thus we obtain a high efficiency of h fa i ¼ 0:79 Æ 0:15. The accretion timescale is hTacc i ¼ 1:05 Æ 0:58 ð Þ ; 108 yr. These results are consistent with Agnor et al. (1999), whose initial con- Fig. 2.—Snapshots of the system on the a-e (left) and a-i (right) planes at t ¼ 0, 1 are proportional to the physical sizes of the planets. KOKUBO, KOMIN 1134 ௕͍࣌ؒΛ͔͚ͯݪ࢝࿭੕ಉ࢜ͷيಓ͕ཚΕΔ ɹˠޓ͍ʹিಥɾ߹ମͯ͠ΑΓେ͖ͳఱମʹ੒௕ <,PLVCP*EB > (c) Hidenori Genda
  21. ਺ϲ݄ʙ਺೥Ͱɺͻͱͭͷ݄͕Ͱ͖Δ δϟΠΞϯτΠϯύΫτʹΑΔ݄ܗ੒

  22. ڊେΨε࿭੕ͷܗ੒ ݪ࢝࿭੕ʹԁ൫Ψε͕๫૸తʹྲྀೖˠΨε࿭੕΁ (c) NVIDIA

  23. Ψεั֫ʹΑΔڊେΨε࿭੕ܗ੒ ݪ࢝࿭੕͸ॏྗʹΑΓपғͷԁ൫ΨεΛั֫ ɾ஍ٿ࣭ྔҎԼˠେؾѹͰࢧ͑ΒΕͯ҆ఆʹଘࡏ ɾ஍ٿ࣭ྔҎ্ˠେؾ่͕յɾ๫૸తʹΨεั֫ يಓ෇ۙʹ࢒͍ͬͯΔΨεΛશͯՃ଎౓తʹั֫ ɹˠٸܹʹ࣭ྔΛ૿͠໦੕ɾ౔੕΁ͱ੒௕͢Δ (c) Nagoya U

  24. प࿭੕ԁ൫಺ͰӴ੕͕ܗ੒ (c) Takayuki Tanigawa ΠΦ Τ΢ϩύ Ψχϝσ ΧϦετ λΠλϯ (c)

    Wikipedia
  25. .BZPS2VFMP[ εΠεͷ؍ଌνʔϜ  ਓྨॳͷܥ֎࿭੕ݕग़ʂ ϖΨαε࠲൪੕ͷपΓʹ)PU+VQJUFS͕ଘࡏʂ ೥݄ ਓྨॳͷܥ֎࿭੕ൃݟ (c) NASA (c)

    Michel Mayor
  26. ଠཅܥ֎࿭੕͕ଓʑͱݟ͔ͭΔ ೥݄೔ݱࡏ  ݸͷܥ֎࿭੕͕֬ೝ

  27. όϥΤςΟʹ෋Ήܥ֎࿭੕ܥ ඪ४తͳ࿭੕ܗ੒γφϦΦʹΑͬͯઆ໌Մೳ͔ʁ (c) NASA (c) Wikipedia (c) NASA (c) picshype.com

  28. ଟ༷ͳݪ࢝࿭੕ܥԁ൫ Դڇ࠲ ΁ͼ͔͍ͭ࠲      ԁ൫ͷ࣭ྔ<ଠཅ࣭ྔ> ൃ

    ݟ ਺ ଠཅܥ෮ݩԁ൫ Ӊ஦ʹ͸༷ʑͳ࣭ྔΛ࣋ͭݪ࢝࿭੕ܥԁ൫͕ଘࡏ ɹˠԁ൫ͷ࣭ྔͷҧ͍͕ଟ༷ͳ࿭੕ܥΛੜΈग़͢ʂʁ
  29. ଟ༷ͳԁ൫͔Βੜ·ΕΔଟ༷ͳ࿭੕ ԁ൫ͷ࣭ྔͷҧ͍ˠΨε࿭੕ͷ਺ͱҐஔͷҧ͍ the escape velocity of protoplanets. This high random

    veloc- ity makes the accretion process slow and inefficient and thus Tgrow longer. This accretion inefficiency is a severe problem On the ot in circular o HD 192263 with Æ1e 1 for in situ f case. It is d slingshot m circular orb the magnet may be wea disks may b Terrestria Jovian plan planetary a key process systems. We confir holds in Æsolid ¼ Æ1 ð ¼ 1=2; 3= tions. We d systems dep disk profile growth tim and (17), re a Mdisk T <T grow disk T <T cont disk Fig. 13.—Schematic illustration of the diversity of planetary systems against the initial disk mass for < 2. The left large circles stand for central stars. The double circles (cores with envelopes) are Jovian planets, and the others are terrestrial and Uranian planets. [See the electronic edition of the Journal for a color version of this figure.] ݪ࢝࿭੕ܥԁ൫ͷ࣭ྔ يಓ௕൒ܘ த৺੕͔Βͷڑ཭ <,PLVCP*EB >
  30. ࿭੕ܥͷଟ༷ੑΛੜΈग़͢ཁૉ ɾݪ࢝࿭੕ܥԁ൫ͷ࣭ྔͷҧ͍ ɹˠΨε࿭੕ͷݸ਺΍Ґஔͷҧ͍ΛੜΉʁ ɾܗ੒தͷ࿭੕ͷத৺੕ํ޲΁ͷམԼ ʢλΠϓ*࿭੕མԼˍλΠϓ**࿭੕མԼʣ ɹˠ࠷ऴతͳ࿭੕ͷҐஔͷҧ͍ΛੜΉʁ ɾ࿭੕ͷҠಈʹ൐͏࿭੕ܥͷมԽ ɹˠΑΓଟ༷ͳ࿭੕ܥ͕ܗ੒͞ΕΔʁ ɾيಓෆ҆ఆʹΑΔ࿭੕ܥͷมԽ ɹˠ௕͍࣌ؒΛ͔͚ͯҟͳΔ࿭੕ܥ΁Ҡߦʁ

  31. ཧ࿦తʹ༧૝͞ΕΔ࿭੕ͷଟ༷ੑ يಓ௕൒ܘ<"6> ࿭੕ͷ࣭ྔ<.&> ஍ٿܕ࿭੕ ڊେණ࿭੕ ڊେΨε࿭੕ )PU+VQJUFS <*EB-JO >