講演＠からつ塾

2019೥9݄21೔ˏ͔Βͭक़, ౜௡ϏδωεΧϨοδ ଠཅܥ஀ੜͷγφϦΦΛඳ͖ग़͢ ژ౎େֶ Ӊ஦෺ཧֶڭࣨɹࠤʑ໦وڭ

ࣗݾ঺հ ⿣ ࠤʑ໦وڭʢ͖͔ͨ͞͞ͷΓʣ ⿣ ژ౎େֶɹେֶӃཧֶݚڀՊɹ෺ཧֶɾӉ஦෺ཧֶઐ߈  Ӊ஦෺ཧֶڭࣨɹॿڭ ⿣ ೥݄ʹ౦ژେֶͰֶҐΛऔಘ ⿣ ઐ໳͸l࿭੕ͷܗ੒ͱਐԽzͷཧ࿦ݚڀ 
ɹ࿭੕ܥ͸ͲͷΑ͏ʹͯ͠࡞ΒΕΔͷ͔  ɹ࿭੕ܥ͸ͲͷΑ͏ʹਐԽ͍ͯ͘͠ͷ͔  ɹ զʑ͸Կॲ͔ΒདྷͯԿॲ΁ߦ͘ͷ͔ʁ ੜ໋Λ॓͢lୈೋͷ஍ٿz͸ଘࡏ͢Δ͔ʁ (c) NASA

ଠཅܥܗ੒࿦ඪ४Ϟσϧ ʮژ౎Ϟσϧʯ

ଠཅܥͷߏ੒ϝϯόʔ ஍ٿܕ࿭੕ ɹɹਫ੕ ɹɹۚ੕ ɹɹ஍ٿ ɹɹՐ੕ ڊେΨε࿭੕ ɹɹɹ໦੕ ɹɹɹ౔੕ ڊେණ࿭੕
ɹɹఱԦ੕ ɹɹւԦ੕ (c) ikachi.org

ݪ࢝ଠཅܥԁ൫ͷ̎ͭͷϞσϧ
©Newton Press ژ౎ϞσϧʢྛϞσϧʣ ΩϟϝϩϯϞσϧ ஍ٿܕ࿭੕ɾڊେΨε࿭੕ɾڊେණ࿭੕ͷ࡞Γ෼͚ ɹˠଠཅܥܗ੒ʹؔͯ͠͸ɺژ౎Ϟσϧͷํʹ܉഑ (c) Alan P. Boss

ژ౎Ϟσϧͷجຊ֓೦ ԁ൫Ծઆ ɾ࿭੕ܥ͸ݪ࢝࿭੕ܥԁ൫͔Βܗ੒͞ΕΔ ɾԁ൫͸࠷খ࣭ྔͷΨεͱμετ͔Βߏ੒͞ΕΔ ඍ࿭੕Ծઆ ɾμετͷूੵʹΑͬͯඍ࿭੕͕ܗ੒͞ΕΔ ɾඍ࿭੕ͷूੵʹΑͬͯݻମ࿭੕͕ܗ੒͞ΕΔ ɾݻମ࿭੕ʹΨε͕߱Γੵ΋Δ͜ͱʹΑͬͯ ɹΨε࿭੕͕ܗ੒͞ΕΔ ɹɹɹɹɹɹɹɹɹɹɹɹ<ྛ஧࢛࿠ଞ
>

ଠཅܥܗ੒ඪ४ཧ࿦ʢژ౎Ϟσϧʣ
©Newton Press ڊେණ࿭੕ܗ੒

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

ݪ࢝࿭੕ܥԁ൫ ෼ࢠӢίΞͷऩॖ ɹॏྗͱԕ৺ྗͷͭΓ͍͋ ݪ࢝࿭੕ܥԁ൫͕ܗ੒ (c) NASA ෼ࢠӢίΞ ݪ࢝࿭੕ܥԁ൫

ݪ࢝ଠཅܥԁ൫ͷ૊੒ Ұൠʹԁ൫࣭ྔͷ͸ΨεʢਫૉɾϔϦ΢Ϝʣ ࢒Γͷ͕μετʢݻମ੒෼ʣ ɾݱࡏͷଠཅܥͷ࿭੕ͷݻମ੒෼ʢ໿.ଠཅʣ ɹɹˠ͢ΓͭͿͯ͠ԁ൫ঢ়ʹͳΒ͢ ɾݻମ੒෼ͷ໿ഒͷ࣭ྔͷΨε੒෼ΛՃ͑Δ ࠷খ࣭ྔԁ൫ϞσϧʢྛϞσϧʣ ݪ࢝ଠཅܥԁ൫ͷॳظ࣭ྔ͸໿.ଠཅ ॏྗͱԕ৺ྗͷ௼Γ߹͍͔Β൒ܘ͸໿"6 4OPXMJOFҎԕͰ͸ਫ͕ڽ݁͠ݻମ໘ີ౓্͕ঢ

ݪ࢝࿭੕ܥԁ൫ͷ؍ଌ ࣮ࡍʹ༷ʑͳܗͷԁ൫͕؍ଌ͞Ε͍ͯΔ ɹˠݪ࢝࿭੕ܥԁ൫͸͔֬ʹଘࡏ͢Δʂ Subaru ALMA

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

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 ☓☓ ☓ ☓☓

ඍ࿭੕ͷ߹ମ੒௕ ਺LNαΠζͷ ඍ࿭੕͕ܗ੒ ޓ͍ʹিಥɾ߹ମ Λ܁Γฦ͠੒௕ ˣ ๫૸త੒௕ ɹେཻ͖͍ࢠ΄Ͳ੒௕͕଎͍ டংత੒௕ ɹશͯͷཻࢠ͕ಉ͡଎౓Ͱ੒௕
(c) Kouji KANBA

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

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 planetesimals. 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 >

Չ઎త੒௕ͷ༷ࢠ FORMATION OF PROTOPLANETS FROM PLANETESIMALS 23 FIG. 7. Snapshots
of a planetesimal system on the a–e plane. The circles 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 >

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

δϟΠΞϯτΠϯύΫτ ݪ࢝࿭੕ಉ࢜ͷڊେఱମিಥΛ܁Γฦ͠ ݱࡏͷ࿭੕΁ (c) NASA

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

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

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

周惑星円盤惑星中心星原始惑星系円盤原始惑ガス惑 (c) Takayuki Tanigawa प࿭੕ԁ൫಺ͰӴ੕͕ܗ੒

ੜ໋Λ॓͢࿭੕ ɹʮ஍ٿʯ͕Ͱ͖Δ·Ͱ

ੜ໋ଘࡏ৚݅ ੜ໋ͷఆٛ ࣗݾͱ֎քΛ۠ผ͢ΔບΛ࣋ͭ͜ͱ ୅ँΛ͢Δ͜ͱ ࣗݾෳ੡Λ͢Δ͜ͱ ࿭੕ͷද໘ʹӷମͷਫ͕ଘࡏ͢Δ͜ͱ ͜ͷΑ͏ͳಛ௃Λ࣋ͬͨʮੜ໋ʯ
͕ੜ·ΕΔͨΊͷඞཁ৚݅ ͜ΕΛศٓతʹ࿭੕Պֶʹ͓͚Δੜ໋ଘࡏ৚݅ͱ͢Δ

࿭੕ද໘ʹӷମͷ ਫ͕ଘࡏͰ͖ΔྖҬ ϋϏλϒϧκʔϯ (c) Wikipedia

(c) USGS l΄Μͷۇ͔zͷਫΛ֫ಘͨ͠஍ٿ

஍ٿͷ୸ૉ॥؀ʢෛͷϑΟʔυόοΫʣ ԹஆԽ ߱ਫྔ૿Ճ ෩Խɾਁ৯ྔ૿Ճ ೋࢎԽ୸ૉ͸ւఈʹݻఆ େؾதͷೋࢎԽ୸ૉআڈ ߱ਫྔݮগ ෩Խɾਁ৯ྔݮগ Ր੒׆ಈͰೋࢎԽ୸ૉ෇Ճ େؾதͷೋࢎԽ୸ૉ͕૿Ճ
פྫྷԽ

஍ٿ಺෦ͷ૚ߏ଄ͷܗ੒ మ ؠੴ Ϛϯτϧ ίΞ ॏྗ෼཭ ϚϯτϧɾίΞ෼Խ ஍ٿ಺෦ͷྫྷ٫ ಺֩ͷܗ੒  ࣓৔ͷൃੜ
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Advanced: ৽͍͠ଠཅܥܗ੒γφϦΦ

ଠཅܥܗ੒࿦ͷ༷ʑͳϞσϧ ʢԁ൫Ψεͷࣗݾॏྗෆ҆ఆʹΑΔ࿭੕ܗ੒Ϟσϧʣ ඍ࿭੕ܗ੒ʴίΞूੵʴΨεूੵʹΑΔͦͷ৔ܗ੒Ϟσϧ Ψε࿭੕ͷҠಈΛߟྀͨ͠l/JDF.PEFMz Ψε࿭੕ͷෳࡶͳҠಈΛߟྀͨ͠l(SBOE5BDL.PEFMz ඍ࿭੕ΑΓখ͞ͳఱମΛߟ͑Δl1FCCMF"DDSFUJPO.PEFMz <-BNCSFDIUT+PIBOTFO > <8BMTIFUBM >
<(PNFTFUBM .PSCJEFMMJFUBM 5TJHBOJTFUBM > <)BZBTIJFUBM > <$BNFSPO >

֤ఱମͷيಓ (c) wakatsuki

l/JDF.PEFMz ɾଠཅܥ͸΋ͱ΋ͱਫۚ஍Ր໦౔ւఱͩͬͨ ɾڊେ࿭੕͸ݱࡏΑΓ΋ίϯύΫτͳྖҬʹݻ·͍ͬͯͨ ɾڊେ࿭੕ಉ࢜ͷॏྗࢄཚͷ݁Ռɺւ͕֎ʹඈ͹͞Εͨ ɾւʹΑͬͯΤοδϫʔεΧΠύʔϕϧτఱମ͕ࢄཚ͞Εͨ ɹɹˠࢄཚ͞Εͨূڌ͕֎ԑఱମͷيಓʹ࢒͞Ε͍ͯΔ ɾࢄཚ͞ΕͨఱମͷҰ෦͕஍ٿ΍݄ʹ΋མԼ͖ͯͨ͠ ɹɹˠޙظॏരܸظͷূڌ͕݄ͷΫϨʔλʔʹ࢒͞Ε͍ͯΔ ɾଠཅܥ͸ਫۚ஍Ր໦౔ఱւʹͳͬͨ <(PNFTFUBM
.PSCJEFMMJFUBM 5TJHBOJTFUBM >

࿭੕མԼ໰୊ 5ZQF*NJHSBUJPOʢ.. ʣ ౳Թԁ൫ͰͷNJHSBUJPOʹΑΔམԼ͕଎͗͢Δ ɹˠݪ࢝࿭੕͕ԁ൫಺ʹੜ͖࢒Εͳ͍<5BOBLBFUBM > 5ZQF**NJHSBUJPOʢ.. ʣ ࿭੕ॏྗʹΑΓHBQΛܗ੒͠ɺԁ൫߱ணͱͱ΋ʹམԼ ɹˠB"6ʹΨε࿭੕Λ࢒ͤͳ͍<)BTFHBXB*EB
> 5ZQF***NJHSBUJPOʢ.d. ʣ $PSPUBUJPOUPSRVFͷQPTJUJWFGFFECBDL ɹˠ௒ߴ଎Ҡಈˍ޲͖͕༧ଌෆՄೳ<.BTTFU1BQBMPJ[PV >

l(SBOE5BDL.PEFMz <8BMTIFUBM > D IUUQXXXFYPDMJNFTDPN

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 ☓☓ ☓ ☓☓

http://sasakitakanori.com ࣾͷຊ ߍੜ΍ΤϯδχΞʹʮҰ໷௮͚ʯͰ఻तʂʂ ʦ૿ิ൛ʧ ԁ өըΛ؍͍ͯΔͱɺ ʮ࣍ݩʯ ҟ࣍ݩʯ ͱ͍͏ݴ༿͕සൟʹग़ ·͢ɻ
͔͠͠ɺ ͦͷ ʮ࣍ݩʯ ΍ ࣍ݩʯ ͷҙຯΛയવͱ஌͍ͬͯ ͸ଟ͍ͱࢥ͍·͕͢ɺ ࣮ࡍͦ ཧղ͢ΔͱͳΔͱɺ ͔ͳΓ೉ ͱࢥ͍·͢ɻ ͜ͰຊॻͰ͸ɺ ͦͷ ʮ࣍ݩʯ ͱ ͍ͬͨԿͳͷ͔Λɺ ʮ૬ରੑཧ ࣗવ୯Ґܥʯ ͳͲͷجૅ͔Β ୺ͷ ʮ%ϒϨʔϯʯ ·Ͱɺ ෼͔ ͘͢ղઆ͍ͯ͠·͢ɻ ཧֶͷ਺ࣜΛಡΈղ͘ ϯγϡλΠϯํఔࣜ ԁ ͷӉ஦࿦ೖ໳Ͱ͸ɺ ֶज़ࢽʹܝ Εͨ࢐৽͔ͭ෩มΘΓͳӉ஦ ԾઆΛωλʹɺ ͍ܰΤοηΠ෩ ʔϞΞΛ·͑͡ͳ͕Βཧ࿦ͷ ຯΛ঺հ͠·͢ɻ ͨɺ ඪ४తͳӉ஦࿦Λྫʹɺ ʮܭ ઀ଓʯ ʮϦʔϚϯͷςϯιϧʯ νͷεΧϥʔʯ ͱ͍ͬͨ΋ͷͷ ͔Βɺ ʮΞΠϯγϡλΠϯํఔ ·Ͱɺ ߴ౓ͳ਺ֶΛߴߍੜ΍α ʔϚϯͰ΋ཧղͰ͖ΔΑ͏ʹॻ ͍͖ͯ͠·͢ɻ ʹഭΔʂ త૝૾ྗͷಾ ମԁ ੈل຤ʹ׆༂ͨ͠ൃ໌Ոɺ χί ςεϥɻ ൴͸ΤδιϯͷϥΠό ͋Γɺ ࠷΋ڪΕΒΕͨஉͩͱݴ ͍ͯ·͢ɻ ໊౓ͷ఺ʹ͓͍ͯ͸Τδιϯʹ ʹͻ͚Λͱ͍ͬͯ·͕͢ɺ ަྲྀ ʹ͸͡·Γɺ ܞଳి࿩ͷݪܕͱ ͑Δಉௐճ࿏ͱߴप೾ൃిػɺ ϨϯδͷجૅͰ͋Δߴप೾೤ͷ ΍ແઢૢॎٕज़ͳͲɺ ݱ୅ٕज़ ૅΛ࡞ͬͨਓ෺ͷҰਓͰ͢ɻ ॻͰ͸ɺ ൴ͷࣗ༝ͳ૝૾ྗͷݯ ୳Γɺ ൴ͷ૑Γग़ٕͨ͠ज़͕ݱ ͓͍ͯ΋຺ʑͱੜ͖ଓ͚͍ͯ ͱΛࣔ͠·͢ɻ *4#/ $ ɹˇ& ఆՁɿຊମ ԁʴ੫ ʮଠཅܥ࿭੕ʯ ʮܥ֎࿭੕ʯ ͷ੒Γཱͪͱɺ ʮଠཅܥʯ ʮ࿭੕ʯ ͷܗ੒ཧ࿦ ݄೔ޕޙ࣌෼@ଋNN ޻ֶࣾ ⼦࿭੕ ⽜ ͷ࿩ ủ ࿭ ੕ ܗ ੒ ࿦ Ứ ΁ ͷ ট ଴ ⽥ ࿭ ੕ ⽦ ͷ ࿩ ࠤ ʑ ໦ ɹ و ڭ ޻ֶࣾ ʮ࿭੕ܗ੒࿦ʯ ΁ͷট଴ ࠤʑ໦ɹوڭ Takanori Sasaki ⼦࿭੕ ⽜ ͷ࿩ ʮ࿭੕ܗ੒࿦ʯ ΁ͷট଴

講演＠からつ塾

講演＠からつ塾

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