The Detectability of Exo-Earths and Super-Earths Via Resonant Signatures in Exozodiacal Clouds
The Detectability of Exo-Earths and Super-Earths Via Resonant Signatures in Exozodiacal Clouds
复制标题
通过外生道云中的共振特征可探测到系外地球和超级地球
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
M. Kuchner
中科院分区：
文献类型：
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作者：
C. Stark;M. Kuchner
直接成像太阳系外的类地行星必然意味着要与来自外太空尘埃的天体物理噪音以及这些行星在外太空云中产生的共振结构作斗争。使用定制的混合辛积分器，我们已经构建了120个由外地球和超地球在圆形轨道上创建的共振结构模型，这些结构与类太阳恒星周围无碰撞的稳态尘埃云相互作用。我们的模型包括了足够多的粒子，以克服以前的模拟的局限性，这些模拟通常由少数长寿命粒子主导，使我们能够定量研究产生的环结构的对比度。我们发现，对于圆形轨道上的行星，对于给定的恒星和尘源分布，共振结构的形态和对比度仅取决于两个参数：行星质量和AP1/2/β，其中AP是行星的半长轴，β是辐射压力力与颗粒引力的比率。我们构建了每个粒子25,000个粒子的多粒子大小模型，并表明在无碰撞的云中，Dohnanyi破碎定律产生一个共振环，其光学厚度由分布中最大的粒子决定，而不是最小的。我们使用这些模型来估计最小质量行星的质量，通过对共振环的观测，对尘埃云和行星轨道的各种假设进行了观测。我们的模拟表明，质量小到MAR质量的几倍的行星可能会在AP≳10AU的碎片盘上产生可检测到的信号。
Directly imaging extrasolar terrestrial planets necessarily means contending with the astrophysical noise of exozodiacal dust and the resonant structures created by these planets in exozodiacal clouds. Using a custom-tailored hybrid symplectic integrator, we have constructed 120 models of resonant structures created by exo-Earths and super-Earths on circular orbits interacting with collisionless steady-state dust clouds around a Sun-like star. Our models include enough particles to overcome the limitations of previous simulations that were often dominated by a handful of long-lived particles, allowing us to quantitatively study the contrast of the resulting ring structures. We found that in the case of a planet on a circular orbit, for a given star and dust source distribution, the morphology and contrast of the resonant structures depend on only two parameters: planet mass and ap1/2/β , where ap is the planet’s semimajor axis and β is the ratio of radiation pressure force to gravitational force on a grain. We constructed multiparticle-sized models of 25,000 particles each and showed that in a collisionless cloud, a Dohnanyi crushing law yields a resonant ring whose optical depth is dominated by the largest grains in the distribution, not the smallest. We used these models to estimate the mass of the lowest mass planet that can be detected through observations of a resonant ring for a variety of assumptions about the dust cloud and the planet’s orbit. Our simulations suggest that planets with mass as small as a few times Mar’s mass may produce detectable signatures in debris disks at ap≳ 10 AU.