Collaborative Research: An Ultrastable Blue Astro Comb for Exoplanet and Cosmology Research

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。近年来，在探测环绕其他恒星运行的大质量行星方面取得了巨大进展。这些令人兴奋的发现是了解其他太阳系的演化以及它们是否可能孕育生命的重要一步。尽管这些发现很诱人，但它们并不是结论性的。据我们所知，天文学家还没有在另一个太阳系中找到一颗可以维持生命的行星。要做到这一点，需要在“宜居带”内找到更小的固体（而不是气体）类地行星，这些行星围绕着一颗恒星运行，在“宜居带”内，行星与恒星的距离是这样的，行星的表面温度可以维持液态水。至少有四种方法可以探测绕恒星运行的行星。到目前为止，最成功的方法是非常仔细地监测恒星的速度。如果速度在它的平均值附近有规律地变化，那么很可能有某个天体在它周围的轨道上，我们正在测量恒星的反射速度，这是由于行星在其轨道上位置的变化。这是一项非常精确的测量，它依赖于用光谱仪进行的极其精确的速度测量。大行星产生最大的速度波动，因此最容易被探测到。但是在可居住区域探测较小的类地行星需要比目前更高的精度。麻省理工学院的Franz Kaertner博士正在设计一种非常稳定和精确的校准机制，以改进径向速度测量。他正在与一些科学同事和几名学生合作，在未来两年内设计和制造该设备。这个新方案使用一种非常快速的脉冲激光，通过摄谱仪在恒星的光谱上刻下精确已知波长的有规则间隔的校准“梳”线。这项新技术将把目前的速度测定标准提高约100倍，足以探测到可居住区内的类地行星。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Great progress has been made in recent years in detecting massive planets orbiting other stars. These exciting discoveries are an important step toward understanding the evolution of other solar systems and whether or not they may harbor life. Tantalizing as these discoveries are, however, they are not conclusive. Astronomers have yet to find a planet in another solar system that could support life as we know it. To do so would require finding smaller solid (not gaseous) earth-like planets orbiting a star within the "habitable zone" where the distance of the planet from the star is such that the surface temperature of the planet can sustain liquid water. There are at least four ways to detect a planet orbiting a star. By far the most successful means to date has been to very carefully monitor the velocity of the star. If the velocity tends to vary regularly about its average value, then it is possible that some celestial body is in orbit around it and we are measuring the reflex velocity of the star due to the changes in the position of the planet in its orbit. This is a very exacting measurement to make and it relies on extremely accurate velocity measurements made with a spectrograph. Large planets create the biggest velocity wiggle and are therefore easiest to detect. But detecting smaller earth like planets in the habitable zone requires much higher precision than is currently available. Dr. Franz Kaertner of the Massachusetts Institute of Technology is designing a very stable and accurate calibration mechanism to improve the radial velocity measurements. He is working with a number of scientific colleagues and several students to design and build the device over the next two years. This new scheme uses a very rapidly pulsed laser to imprint a regularly spaced calibration "comb" of lines of precisely known wavelengths through the spectrograph and onto the spectrum of the star. This new technique will improve the velocity determination from the current standard by about a factor of 100, enough to detect earth-like planets in the habitable zone.