The Transit Spectrum of Extrasolar Planet HD 209458b

AST 0307841 PI哈林顿·利特尔（英语：HarringtonLittle）已经被测量过任何太阳系外行星，除了（通常最小）质量、（很少）半径和加热。发现的“热木星”系外行星完全没有被预测到，可能是一种不同于木星和海王星的新类型的巨行星。模型表明，围绕星星HD 209458的行星形成时是热的，但对于它是如何形成的，没有完全一致的方案。测量化学物质的丰度、云的位置，甚至是一颗行星的温度，都可以指导现在几乎不受约束的建模工作。研究人员正在开发一种分析太阳系外行星凌日光谱的新技术，并将其应用于对凌日行星HD 209458b的观测。他们在16个晚上在四个天文台成功地观测到了这个系统。数据在红外线范围很广。一个富含水、甲烷和一氧化碳分子的地区。在运输过程中，行星的大气层应该以千分之一的比例调制恒星光谱，从而提供一种直接测量这颗“热木星”行星的方法。只有新技术才能探测到如此微弱的地面信号。研究者们丰富而高质量的数据使得基于主成分分析的更好的方法成为可能，该方法可以独立于模型推导出凌日调制，因为行星信号应该在凌日的开始和结束时打开和关闭。更广泛的影响：公众对其他行星上的水（甚至是热彗星上的水蒸气）感兴趣，因为它与生命和可居住的行星有关。这个项目足够引人注目，外行人往往有兴趣学习光谱学是如何工作的，所以它是一个有用的教育例子。这些数据是如此详尽，无论成功还是失败，都将为天基太阳系外行星科学提供宝贵的经验教训。

AST 0307841PI HarringtonLittle has been measured for any extrasolar planet except (usually minimum) mass, (rarely) radius, and heating. The "hot Jupiter" extrasolar planets found were entirely unpredicted and may be a new class of giant planet distinct from Jupiters and Neptunes. Models indicate that the planet around the star HD 209458 formed hot, but there are no entirely consistent scenarios for how it formed. Measuring chemical abundances, cloud locations, and the temperature of even one planet would guide modeling efforts that are now almost unconstrained. The investigators are developing a new technique for analyzing extrasolar planet transit spectra, and will apply it to their observations of the transiting extrasolar planet HD 209458b. They observed this system successfully on 16 nights at four observatories. The data span a wide range in the infrared. a region rich in molecular absorptions from water, methane, and carbon monoxide. In transit, the planet's atmosphere should modulate the stellar spectrum by a part in a thousand, providing a way to measure this "hot Jupiter" planet directly. Only novel techniques can detect such a weak signal from the ground. The investigators' abundant and high-quality data enable a better approach, based on principal components analysis, that can derive the transit modulation independently of a model since the planetary signature should turn on and off at the start and end of the transit.Broader Impact: The public is interested in water on other planets (even water vapor on hot Jupiters), because of the connection with life and habitable planets. The project is compelling enough that lay people tend to be interested in learning how the spectroscopy works, so it is a useful educational example. The data are so exhaustive that either success or failure will provide valuable lessons for space-based extrasolar planetary science.