...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Astronomy and astrophysics >Fourier spectra from exoplanets with polar caps and ocean glint
【24h】

Fourier spectra from exoplanets with polar caps and ocean glint

机译：来自带有极冠和海洋闪烁的系外行星的傅立叶光谱

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Context. The weak orbital-phase dependent reflection signal of an exoplanet contains information on the planet surface, such as the distribution of continents and oceans on terrestrial planets. This light curve is usually studied in the time domain, but because the signal from a stationary surface is (quasi)periodic, analysis of the Fourier series may provide an alternative, complementary approach. Aims. We study Fourier spectra from reflected light curves for geometrically simple configurations. Depending on its atmospheric properties, a rotating planet in the habitable zone could have circular polar ice caps. Tidally locked planets, on the other hand, may have symmetric circular oceans facing the star. These cases are interesting because the high-albedo contrast at the sharp edges of the ice-sheets and the glint from the host star in the ocean may produce recognizable light curves with orbital periodicity, which could also be interpreted in the Fourier domain. Methods. We derive a simple general expression for the Fourier coefficients of a quasiperiodic light curve in terms of the albedo map of a Lambertian planet surface. Analytic expressions for light curves and their spectra are calculated for idealized situations, and dependence of the spectral peaks on the key parameters inclination, obliquity, and cap size is studied. Results. The ice-scattering and ocean glint contributions can be separated out, because the coefficients for glint are all positive, whereas ice sheets lead to even-numbered, higher harmonics. An in-view polar cap on a planet without axial tilt only produces a single peak. The special situation of edge-on observation, which is important for planets in transit, leads to the most pronounced spectral behavior. Then the respective spectra from planets with a circumventing ocean, a circular ocean (eyeball world), polar caps, and rings, have characteristic power-law tails n-2, n?7/2, n-4, and (?1)n + 1n-2. Conclusions. Promising recently discovered planetary systems may be selected as candidates for long-term (multiyear) observation: their Fourier spectra could separate the different planets and reveal or identify a water-covered planet with polar caps.
机译：上下文。系外行星的弱于轨道相位的反射信号包含有关行星表面的信息，例如陆地行星上的大陆和海洋的分布。通常在时域中研究此光曲线，但是由于来自固定表面的信号是（准）周期性的，因此对傅立叶级数的分析可能会提供一种替代的补充方法。目的我们从反射光曲线研究傅立叶光谱，以实现简单的几何形状。根据其大气特性，可居住区域中的旋转行星可能具有圆形极地冰盖。另一方面，潮汐锁定的行星可能具有面向恒星的对称圆形海洋。这些情况很有趣，因为在冰盖的锋利边缘处的高反照率对比度和海洋中来自主恒星的闪光可能会产生具有轨道周期性的可识别光曲线，这也可以在傅立叶域中解释。方法。我们根据朗伯行星表面的反照率图，得出了准周期光曲线的傅立叶系数的简单通用表达式。计算了理想情况下的光曲线及其光谱的解析表达式，并研究了光谱峰值与关键参数的倾斜度，倾斜度和瓶盖尺寸的相关性。结果。可以将冰散射和海洋闪烁的贡献分开，因为闪烁的系数都为正，而冰盖会导致偶数，更高的谐波。没有轴向倾斜的行星上的可见极帽只会产生一个峰值。边上观察的特殊情况对运输中的行星很重要，这会导致最明显的光谱行为。然后，来自具有环绕海洋，圆形海洋（眼球世界），极盖和环的行星的各自光谱具有特征幂律尾巴n-2，n？7/2，n-4和（？1） n + 1n-2。结论。可以选择有希望的近期发现的行星系统作为长期（多年）观测的候选者：它们的傅里叶光谱可以分离不同的行星，并揭示或识别出一个带有极盖的被水覆盖的行星。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号