講演＠第78回花山天体観望会

第78回 花山天体観望会 「月」の講演資料です。

Transcript

1. ژ౎େֶ
   Ӊ஦෺ཧֶڭࣨ
   ࠤʑ໦وڭ ୈճ
   Ֆࢁఱମ؍๬ձ
   ʮ݄ʯ
2. Realliq.info NASA
3. ݄ ɾਓྨ͕߱Γཱͬͨ།Ұͷ஍ٿ֎ఱମ
   ɾ஍ٿ͔Βͷڑ཭ɿສLN
   ɾ൒ܘɿLNʢ஍ٿͷഒʣ
   ɾ࣭ྔɿºLHʢ஍ٿͷഒʣ
   ɾ஍ٿʹৗʹಉ͡໘Λ޲͚͍ͯΔ
   ɾ஍ٿͱൺ΂ͯίΞʢ'Fʣ͕খ͍͞ ද ཪ •  ik d T   T (Fe) hT 0 Wikipedia
4. XIII. On the Precession of a Viscous Spheroid, and on the remote History of the Earth. By G. H. Darwin, M.A., Fellow of Trinity College, Cambridge. Communicated by J. W. L. Glaisher, M.A., FM.S. Received July 22, —Read December 19, 1878, Plate 36. The following paper contains the investigation of the mass-motion of viscous and imperfectly elastic spheroids, as modified by a relative motion of their parts, produced in them by the attraction of external disturbing bodies ; it must be regarded as the continuation of my previous paper/" where the theory of the bodily tides of such spheroids was given. The problem is one of theoretical dynamics, but the subject is so large and complex, that I thought it best, in the first instance, to guide the direction of the speculation by considerations of applicability to the case of the earth, as disturbed by the sun and moon. In order to avoid an incessant use of the conditional mood, I speak simply of the earth, sun, and moon ; the first being taken as the type of the rotating body, and the two latter as types of the disturbing or tide-raising bodies. This course will be justi- “෼྾આ” ʹΑΔ݄ܗ੒γφϦΦ Faculty.virginia.edu
5. ݄ͷىݯઆ ั֫આ ෼྾આ ૒ࢠઆ ݪ࢝஍ٿ͕ߴ଎ճసʹΑΓ;͘ΒΈ
   ͦͷҰ෦͕ͪ͗Ε݄͕ͯ஀ੜ ஍ٿيಓ෇ۙͰͷඍ࿭੕ͷूੵʹΑΓ
   ஍ٿͱ͸ಠཱʹ݄͕ܗ੒ ஍ٿͱ͸ผͷ৔ॴͰ࡞ΒΕ݄͕ͨ
   ஍ٿͷۙ͘Λ௨ͬͨͱ͖ʹัΒ͑ΒΕͨ
6. Ξϙϩܭըɿ݄ͷੴͷ࠾औ Getty Images NASA
7. (1) ஍ٿʔ݄ܥͷ֯ӡಈྔʢLtotal ͕อଘʣ ɹˠ ஍ٿ͸Ҏલʹߴ଎ճస͍ͯͯ͠͸͍͚ͳ͍ (2) ஍ٿΑΓ௿ີ౓ʢίΞ͕খ͍͞ʣ[Hood & Zuber, 2000] ɹˠ ݄͸΄΅ؠੴ͚ͩͰͰ͖͍ͯΔ (3) شൃੑݩૉ͕ڧ͘ރׇ [Jones & Palme, 2000]
 (4) ද໘͕େن໛༹༥Λܦݧ [Warren, 1985] ɹˠ ݄͸ߴԹͷঢ়ଶ͔Βελʔτ͍ͯ͠Δ
 (5) ࢎૉಉҐମൺ͕஍ٿͱ΄΅Ұக [Wiechert et al., 2001] ݄ܗ੒Ͱຬͨ͢΂͖৚݅ ɹˠ ݄ͱ஍ٿͷؠੴ͸ಉ͡΋ͷ͔ΒͰ͖͍ͯΔ
8. ݄ͷىݯઆ ั֫આ ෼྾આ ૒ࢠઆ ݪ࢝஍ٿ͕ߴ଎ճసʹΑΓ;͘ΒΈ
   ͦͷҰ෦͕ͪ͗Ε݄͕ͯ஀ੜ ஍ٿيಓ෇ۙͰͷඍ࿭੕ͷूੵʹΑΓ
   ஍ٿͱ͸ಠཱʹ݄͕ܗ੒ ஍ٿͱ͸ผͷ৔ॴͰ࡞ΒΕ݄͕ͨ
   ஍ٿͷۙ͘Λ௨ͬͨͱ͖ʹัΒ͑ΒΕͨ ஍ٿͷ֯ӡಈྔ͕େ͖͗͢Δ ݄ͷ಺෦ߏ଄͕આ໌Ͱ͖ͳ͍ ݄ͱ஍ٿͷؠੴͷҰகΛઆ໌Ͱ͖ͳ͍
9. δϟΠΞϯτΠϯύΫτઆ [Hartman & Davis, Icarus, 1975] [Cameron & Ward, LPI Conference, 1976] Wikipedia
10. ڊେఱମিಥʹΑΔԁ൫ܗ੒ [Canup & Asphaug, Nature, 2001] © Natsuki Hosono ݪ࢝஍ٿʹՐ੕αΠζͷ ݪ࢝࿭੕͕িಥ ඈͼࢄͬͨഁย͕஍ٿͷ
    पғʹԁ൫Λܗ੒ ͜ͷഁยΛࡐྉʹͯ͠
    ݄͕ܗ੒͞ΕͨͷͰ͸ʁ
11. Roche radius, whereas Fig. 3 is a rather extended disk case (run 9). The extension of a disk is indicated by Jdisk /Mdisk , where Jdisk is the total angular momentum of the starting disk. For the disks in Figs 2 and 3, Jdisk /Mdisk are0:692 GM!aR and 0:813 GM!aR , respectively. Figure 3 The same snapshots as in Fig. 2 but for run 9 of a more extended disk (J disk =M disk ¼ 0:813 GM ! a R ). At t ¼ 1,000 the largest moon mass is 0.71M L. [Ida et al., Nature, 1997] FIG. 2. Snapshots of the circumterrestrial disk projected on the R–z plane at t = 0, 10, 30, 100, 1000TK for runs (a) 29a centered at the coordinate origin stands for Earth. Circles represent disk particles and their size is proportional to the physic [Kokubo et al., Icarus, 2000] িಥഁยԁ൫͔Βͷ݄ܗ੒
12. ݄ܗ੒γϛϡϨʔγϣϯ ਺ϲ݄ʙ਺೥Ͱɺͻͱͭͷ݄͕Ͱ͖Δ [Sasaki & Hosono, ApJ, 2018] [Simulation by Natsuki Hosono]
13. “ଠཅܥ࠷ݹͷ෺࣭͕ܗ੒͞Ε͔ͯΒ໿3,000ສ೥ޙ ݪ࢝஍ٿʹՐ੕αΠζͷݪ࢝࿭੕͕ࣼΊিಥ͠ ඈͼࢄͬͨϚϯτϧ෺࣭͕प࿭੕ԁ൫Λܗ੒͠ ͦΕΒ͕໿਺೥͔͚ͯूੵ͠ɺ݄͕஀ੜͨ͠”
14. ݄ܗ੒Ͱຬͨ͢΂͖৚݅ (1) ஍ٿʔ݄ܥͷ֯ӡಈྔʢLtotal ͕อଘʣ (2) ஍ٿΑΓ௿ີ౓ʢίΞ͕খ͍͞ʣ[Hood & Zuber, 2000] (3) شൃੑݩૉ͕ڧ͘ރׇ [Jones & Palme, 2000] (4) ද໘͕େن໛༹༥Λܦݧ [Warren, 1985] (5) ࢎૉಉҐମൺ͕஍ٿͱ΄΅Ұக [Wiechert et al., 2001] δϟΠΞϯτΠϯύΫτઆͰ͸આ໌Ͱ͖ͳ͍ʂʁ ੈքதͰ৽͍͠ΞΠσΞ΍ܗ੒γφϦΦΛݕূத Hosono et al. (2019), Sasaki & Hosono (2019), etc…