Planetary Growth: Time Frames and Challenges

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  • Recent numerical studies have provided insights into the growth times of planets such as Earth, Jupiter, and Neptune.
  • The growth times for Earth and Jupiter are estimated to be around 10^6 to 10^7 years and 10^7 to 10^8 years, respectively.
  • However, the growth time for Neptune is much longer, possibly comparable to or longer than the age of the solar system.
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これの和訳を教えてください。

Recently, Nakagawa et al. have numerically studied the planetary growth and shown that the growth times of the Earth and Jupiter are orders 10^6~10~7 yrs and 10^7~10^8 yrs, respectively. But, for the case of Neptune, a very long time, which is comparable to or longer than the age of the solar system, is needed for the growth ( these growth times, nevertheless, are shorter by a factor of 10 or 100 than those obtained by Safronov). As they have pointed out for themselves, their results are not always final but tentative because in their calculation some assumptions and simplifications are made for the sake of convenience; one of these is that for the rates of collision and of gravitational scattering due to the mutual encounters between planetesimals, formulae in a free space (i.e., without the influence of the solar gravity) are used.

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  • ddeana
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回答No.1

最近、中川その他(※1)は惑星の成長を数値的に研究し、地球と火星の成長時間がそれぞれ10の6乗から10の7乗年と、10の7乗から10の8乗年と表した。 しかし、海王星の場合は、成長するのに太陽系の年齢に匹敵するかそれよりも長い時間が必要とされる(とは言っても、こうした成長時間はサフロノフが計算したものよりも10か100倍短いものである)。彼らが自分で指摘した通り、こうした結果は常に最終的なものではなく暫定的なものだ。なぜなら計算において便宜上いくつかの仮定と簡素化がなされているから。その内のひとつは、微惑星間の相互衝突の為の衝突と重力拡散の比率であり、自由空間での公式(つまり、太陽の重力に左右されることがない)が使われている。 ※1:et al:論文などで共同著者が多い場合、代表者以外をこのように「その他」と表す場合が多いです。

stargazer1231
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