| アブストラクト |
Perhaps the newest and highest profile sub-field of astronomy is the study of extrasolar planets. Although the first paper claiming the discovery of an extrasolar planet was published more than 150 years ago, the exoplanet sub-field of astronomy didn't begin to form until the discovery of the first hot Jupiter by Mayor and Queloz in 1995. Since then the field has grown quite rapidly. In the first half of the lecture, I review the variety of methods that have been used to study extrasolar planets highlighting the strengths and weaknesses of each method. I also give an overview of planet formation theory and the challenges that these theories face.
In the second half of my lecture, I focus on the gravitational microlensing method. I discuss the basics of the method and explain its special sensitivity to planets located beyond the so-called "snow-line", where the most massive planets are thought to form. I also show how microlensing is able to detect free-floating planets that have been ejected from the planetary systems of their birth. Finally, I show how a space-based microlensing survey, like the US WFIRST mission, can complete the statistical census of exoplanets that has begun with the Kepler mission. The census resulting from the combination of these two missions will extend down to planets smaller than the Earth at all orbital separations from 0 to infinity. The data gained from WFIRST will be invaluable for advancing our understanding of the planet formation process and will aid in the planning of a future mission that will search for signs of life via spectroscopy of Earth-like planets orbiting nearby stars. |
| キーワード |
astronomy, extrasolar planets, exoplanet, gravitational microlensing method, snow-line, free-floating planets, the US WFIRST mission, planet formation |
