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A study of ejection times of terrestrial planets from the habitable zones of the solar twins HD 20782 and HD 188015.

机译：研究了从太阳双胞胎HD 20782和HD 188015的可居住区域射出的地球行星的射出时间。

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摘要

We provide a detailed statistical study of the ejection of terrestrial planets from the habitable zones of the solar twins HD 20782 and HD 188015. These systems possess a giant planet that crosses into the stellar habitable zone, thus effectively thwarting the possibility of habitable terrestrial planets. In case of HD 188015, the orbit of the giant planet is essentially circular, whereas in case of HD 20782, it is extremely elliptical. As starting positions for the giant planets, we consider both the apogee and perigee position, whereas the starting positions of the terrestrial planets are widely varied. For the giant planets, we consider models based on their minimum masses as well as models where the masses are increased by 30%. Our simulations indicate a large range of statistical properties concerning the ejection of the terrestrial planets from the stellar habitable zones. For example, it is found that the ejection times for the terrestrial planets from the habitable zones of HD 20782 and HD 188015, originally placed at the center of the habitable zones, vary by a factor of ∼200 and ∼1500, respectively, depending on the starting positions of the giant and terrestrial planets. If the mass of the giant planet is increased by 30%, the variation in ejection time for HD 188015 increases to a factor of ∼6000. As a further application of this thesis we challenge the customary assumption that the entering of a terrestrial planet into the Hill radius (or multiples of the Hill radius) of a giant planet is a valid criterion for its ejection from the star-planet system. This assumption has been widely used in previous studies, especially those with an astrobiological focus. It has been found from our study that even though the terrestrial planets are eventually ejected from the habitable zones of both systems, the "Hill Radius Criterion" is identified as invalid for the prediction of when the ejection is actually occurring.
机译：我们提供了详细的统计研究，研究了从太阳双胞胎HD 20782和HD 188015的宜居带中弹出的地球行星。这些系统拥有一个穿越恒星宜居区域的巨型行星，从而有效地阻止了宜居地球行星的可能性。在HD 188015的情况下，巨型行星的轨道基本上是圆形的，而在HD 20782的情况下，它的椭圆形非常大。作为巨型行星的起始位置，我们同时考虑了远地点和近地点，而陆地行星的起始位置则差异很大。对于巨型行星，我们考虑基于其最小质量的模型以及质量增加30％的模型。我们的模拟结果表明，有关恒星从宜居区域射出的行星的统计特性范围很大。例如，发现最初放置在可居住区中心的HD 20782和HD 188015可居住区对地球行星的喷射时间分别变化约200和1500。巨型和陆地行星的起始位置。如果巨型行星的质量增加30％，则HD 188015的喷射时间变化会增加到约6000。作为本论文的进一步应用，我们挑战惯常的假设，即将地球行星进入巨型行星的希尔半径（或希尔半径的倍数）是将其从星行星系统中弹出的有效标准。该假设已在以前的研究中广泛使用，尤其是那些以天体生物学为重点的研究。从我们的研究中发现，即使最终从两个系统的宜居区域中弹出了地球行星，“希尔半径准则”也被认为对于预测何时实际发生弹出是无效的。

著录项

  • 作者

    Yeager, Katherine Elizabeth.;

  • 作者单位

    The University of Texas at Arlington.;

  • 授予单位 The University of Texas at Arlington.;
  • 学科 Physics Astronomy and Astrophysics.
  • 学位 M.S.
  • 年度 2009
  • 页码 105 p.
  • 总页数 105
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 天文学;
  • 关键词

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