講演＠第72回花山天体観望会

第72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. ݄ͷىݯઆ ั֫આ ෼྾આ ૒ࢠઆ ݪ࢝஍ٿ͕ߴ଎ճసʹΑΓ;͘ΒΈ
   ͦͷҰ෦͕ͪ͗Ε݄͕ͯ஀ੜ ஍ٿيಓ෇ۙͰͷඍ࿭੕ͷूੵʹΑΓ
   ஍ٿͱ͸ಠཱʹ݄͕ܗ੒ ஍ٿͱ͸ผͷ৔ॴͰ࡞ΒΕ݄͕ͨ
   ஍ٿͷۙ͘Λ௨ͬͨͱ͖ʹัΒ͑ΒΕͨ ߴ଎ճస͕೉͍͠
   
   ֯ӡಈྔ͕େ͖͗͢Δ ݄ͷ಺෦ߏ଄͕આ໌Ͱ͖ͳ͍
   
   ݄Λ࢒ͤͳ͍ ั֫֬཰͕௿͍
   
   Խֶత੍໿Λຬͨͤͳ͍
8. δϟΠΞϯτΠϯύΫτઆ [Hartman & Davis, Icarus, 1975] [Cameron & Ward, LPI Conference, 1976] Wikipedia
9. ڊେఱମিಥʹΑΔԁ൫ܗ੒ ݪ࢝஍ٿʹՐ੕αΠζͷ ݪ࢝࿭੕͕িಥ ඈͼࢄͬͨഁย͕஍ٿͷ
   पғʹԁ൫Λܗ੒ [Canup & Asphaug, Nature, 2001] © Natsuki Hosono
10. 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੒
11. ௒ߴղ૾౓Ͱͷ݄ܗ੒ܭࢉ [Sasaki & Hosono, 2018]
12. “ଠཅܥ࠷ݹͷ෺࣭͕ܗ੒͞Ε͔ͯΒ໿3,000ສ೥ޙ ݪ࢝஍ٿʹՐ੕αΠζͷݪ࢝࿭੕͕ࣼΊিಥ͠ ඈͼࢄͬͨϚϯτϧ෺࣭͕प࿭੕ԁ൫Λܗ੒͠ ͦΕΒ͕໿਺೥͔͚ͯूੵ͠ɺ݄͕஀ੜͨ͠”
13. ͸ԕ͍͚Ͳɼ ·ͩͩΕ΋஌Βͳ͍͜ ͱΛࣗ෼͕࠷ॳʹ஌Δ͜ ͱͷتͼ΍Θ͘Θ Ε͕޷͖͔ͩΒɼ ݚڀΛଓ͚͍ͯΔͷͩͱࢥ͍·͢ɻ “ࠃޠ” ͷڭՊॻʹࡌΔ ޫଜਤॻ
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] (6) ೉شൃੑݩૉͷಉҐମൺ͕஍ٿͱ΄΅Ұக [Touboul et al., 2007] (7) Si ಉҐମൺ͕஍ٿͱ΄΅Ұக [Armytage et al., 2012] δϟΠΞϯτΠϯύΫτઆͰ͸આ໌Ͱ͖ͳ͍ʂʁ
15. the deformed o the Moon. ocean can be element parti- nciples of the rimental data ne and ultra- magma ocean value of Mg# ed by a broad 920–80%) or e of chemical n the process ct and partial modify the composition (e.g., ref. 24). The present model could also explain the presence of a small Fe-rich core,25) if the influence of reduction at high proto-Earth proto-Earth impactor impactor magma ocean vapor jet (a) (b) Fig. 4. Schematic drawing of processes of ejection of materials upon a giant impact. (a) A case where the proto-Earth does not have a magma ocean. (b) A case where the proto-Earth has a magma ocean. fate of ejected materials depends on the ratio h/R and materials with only for modest value of h/R and velocity will become the source of the Moon. m/s) The temperature he relation [1] in mperature at the e summarized in olume, q : a non- (q9 1 for solids, [Karato, Proc. Jpn. Acad., 2014] Giant Impact on Magma Ocean Magma Ocean ঢ়ଶͷݪ࢝஍ٿ΁ͷ Giant Impact ΞΠσΞͷఏҊ͚ͩͰ਺஋ܭࢉ౳͸ߦΘΕ͍ͯͳ͍
16. High-Energy Giant Impact ஍ٿͷϚϯτϧ͸ G.I. Ͱ͍ͬͨΜશͯৠൃͨ͠ʂʁ [Wang & Jacobson, Nature, 2016]
17. Multiple Impact Scenario NATURE GEOSCIENCE DOI: 10.1038/NGEO2866 ARTICLES a −60 −45 −30 −15 0 15 30 45 60 V imp /V esc V imp /V esc 1.0 1.4 2.0 3.0 4.0 1.0 1.4 2.0 3.0 4.0 M moon M moon 1.0 0.5 0.1 9 5 2.4 1 0 10 20 30 40 50 60 b 1.0 0.5 0.1 9 5 2.4 1 10 20 30 40 50 60 Impact angle, (°) β |δf T | (%) |δf T | (%) a L imp /L EM L final /L EM −4 −2 0 2 4 M sat /M moon 10−2 10−1 100 b 1.0 1.5 2.0 2.5 3.0 |δf T | < 10 Graze and merge Hit and run Partial accretion / max = 0.00 ω ω / max = 0.25 ω ω / max = 0.50 ω ω NATURE GEOSCIENCE DOI: 10.1038/NGEO2866 ARTICLES a −60 −45 −30 −15 0 15 30 45 60 V imp /V esc V imp /V esc 1.0 1.4 2.0 3.0 4.0 1.0 1.4 2.0 3.0 4.0 V imp /V esc 1.0 1.4 2.0 3.0 4.0 M moon M moon M moon 1.0 0.5 0.1 9 5 2.4 1 0 10 20 30 40 50 60 b 1.0 0.5 0.1 9 5 2.4 1 0 10 20 30 40 50 60 c 1.0 0.5 0.1 9 5 2.4 1 10 20 30 40 50 60 Impact angle, (°) β −60 −45 −30 −15 0 15 30 45 60 Impact angle, (°) β |δf T | (%) |δf T | (%) |δf T | (%) a L imp /L EM L final /L EM L imp /L EM −4 −2 0 2 4 M sat /M moon 10−2 10−1 100 b −6 −4 −2 0 2 4 6 0.0 0.5 1.0 1.5 2.0 2.5 3.0 |δf T | < 10 Graze and merge Hit and run Partial accretion / max = 0.00 ω ω / max = 0.25 ω ω / max = 0.50 ω ω Figure 4 | Final satellite mass and system angular momentum. a, Mass of the formed satellite using equation (2) as a function of impact angular momentum for !=0.25!max rotation. The colours correspond to di￿erent collisional regimes (hit and run—impactor escapes partially intact; graze and merge—impactor impacts the target twice; partial accretion—addition of mass to the target). b, The final angular momentum of all the systems that created a satellite. The di￿erent styles of markers represent di￿erent initial rotations. The darker horizontal lines represent the initial planetary angular momentum value with colours corresponding to the colours of the markers. Disks containing <100NSPH were omitted. −60 −45 −30 −15 0 15 30 45 60 V im V imp /V esc 1.0 1.4 2.0 1.0 1.4 2.0 3.0 4.0 V imp /V esc 1.0 1.4 2.0 3.0 4.0 M moon M moon 0 10 20 b 1.0 0.5 0.1 9 5 2.4 1 0 10 20 30 40 50 60 c 1.0 0.5 0.1 9 5 2.4 1 0 10 20 30 40 50 60 Impact angle, (°) β −60 −45 −30 −15 0 15 30 45 60 Impact angle, (°) β −60 −45 −30 −15 0 15 30 45 60 Impact angle, (°) β (%) |δf T | (%) |δf T | (%) Figure 3 | Disk properties in the angle–velocity phase space. a–c, Initial planetary rotation rate !=0.10!max (a), !=0.25!max (b) and !=0.50!max (c). The marker size corresponds to disk mass and the colour to the compositional di￿erence between the silicates in the final planet and disk. For comparison, the grey circles in the upper left corner represent a disk mass of 0.1, 0.5 and 1 MMoon. Markers are shifted horizontally according to the mass ratio, from left to right (9, 5, 2.4, 1%). The grey dots indicate disks that have an iron content larger than the estimated lunar core mass of 0.1Mmoon. Disks containing <100 smoothed particle hydrodynamics (SPH) particles were omitted. retrograde impactors often fail to form a disk with enough angular momentum to accrete a moonlet. Fi th m co an o th in an m h F ro g er d th p H p m im m re an [Rufu et al., Nature Geo., 2017] 20 ճఔ౓ͷিಥͰܗ੒͞Εͨ moonlets ͷूੵ িಥதͷ previous moonlets ͷ҆ఆੑʹ͍ͭͯ͸ෆ໌
18. 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଴ ৽ץຊ͕ग़·ͨ͠ʂ