The Transit Spectrum of Extrasolar Planet HD 209458b

除了质量(通常是最小的)、半径(很少)和加热外，任何太阳系外行星的哈灵顿都被测得很少。被发现的太阳系外热木星行星完全出乎意料，可能是一种有别于木星和海王星的新的巨型行星。模型表明，围绕恒星HD 209458的行星形成了热，但对于它是如何形成的，并没有完全一致的假设。即使测量一颗行星的化学丰度、云层位置和温度，也可以指导现在几乎不受限制的建模工作。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，并将把它应用于他们对凌日太阳系外行星HD 209458b的观测。他们在四个天文台的16个晚上成功地观测到了这个系统。这些数据在红外范围内覆盖很广。富含水、甲烷和一氧化碳分子吸收的区域。在凌日过程中，行星的大气层应该会以千分之一的比例调制恒星光谱，从而提供了一种直接测量这颗“热木星”行星的方法。只有新技术才能从地面探测到如此微弱的信号。研究人员丰富而高质量的数据提供了一种更好的方法，基于主成分分析，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开始和结束时打开和关闭。广泛的影响：公众对其他行星上的水(甚至热木星上的水蒸气)感兴趣，因为它与生命和宜居行星有关。这个项目很有说服力，外行人往往对了解光谱学是如何工作的感兴趣，所以它是一个有用的教育例子。这些数据是如此详尽，无论是成功还是失败，都将为基于空间的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.