New atomic and molecular data for astrophysics by high resolution Fourier Transform Spectroscopy

摘要：地面和天基望远镜上的新的高分辨率光谱仪使天文学家能够观测到前所未有的质量的天体物理光谱，并导致迫切需要足够准确和完整的原子数据来分析这些光谱。尤其重要的是铁族元素(钛、钒、铬、锰、铁、钴、镍)丰富的谱线。在许多情况下，双电离铁族光谱的原子数据非常陈旧、不完整和不准确，在中性和单电离物种的红外光谱中往往完全缺失。使用帝国理工学院独特的可见光-紫外傅里叶变换(FT)光谱仪和美国NIST(美国国家标准与技术研究所)FT光谱仪，我们将研究这些元素的高分辨率光谱。使用FT光谱仪的优点是，我们可以在很大的光谱范围内以高分辨率测量特定物种的光谱。我们将专注于在波长精度、原子能级、振子强度(确定天体中元素丰度所需的)和超精细结构方面至少有数量级改进的测量。天文学家使用这些原子数据来分析天体物理光谱。一旦测量，原子数据将立即用于我们正在合作的特定天体物理项目，例如：低质量恒星、棕矮星和额外的太阳行星、热星和化学奇特恒星。我们还计划对宇宙学应用中使用的谱线的准确波长进行测量：特别是在研究精细结构常数可能随时间变化的过程中，精细结构常数是基本常数之一。我们产生的所有新的实验室原子和分子数据都被纳入数据库和模型大气代码，使世界各地的天文学家和英国的天文学家受益。我们向天文学团体提供的新的实验室数据意味着，对昂贵获得的现代天体物理光谱的分析将不再受到分析中使用的原子(或分子)数据的质量和数量的限制。除了原子数据测量计划外，我们还计划一个新的高分辨率SO2分子光谱项目，其中包括在紫外光中进行低温测量，以获得研究木星卫星Io火山活动所急需的分子数据。

Summary: New high resolution spectrographs on both ground and space-based telescopes have allowed astronomers to observe astrophysical spectra of unprecedented quality, and have led to an urgent need for atomic data of sufficient accuracy and completeness to analyse these spectra. Particularly important are the abundant, line rich spectra of the iron group elements (Ti, V, Cr, Mn, Fe, Co, Ni). Atomic data of the doubly ionised iron group spectra are in many cases very old, incomplete, and inaccurate, and in the case of the infra red spectra of neutral and singly ionised species are often missing entirely. Using our unique visible-ultraviolet Fourier Transform (FT) spectrometer at Imperial College and the NIST (National Institute Standards & Technology, USA) FT spectrometer we will study high resolution spectra of these elements. The advantages of using an FT spectrometer are that we can measure the spectrum of a particular species at high resolution over a wide spectral range. We will focus on measurements leading to at least order-of-magnitude improvements in wavelength accuracy, atomic energy levels, oscillator strengths (needed for determining abundances of elements in astrophysical objects), and hyperfine structure. Astronomers use these atomic data in analysing astrophysical spectra. Once measured the atomic data will be used immediately in specific astrophysics projects we are collaborating on, examples include: Low mass stars, brown dwarfs and extra solar planets, hot stars, and chemically peculiar stars. We also plan measurements of accurate wavelengths of lines for use in cosmology applications: in particular in investigations of a possible time variation in the fine structure constant, one of the fundamental constants. All the new laboratory atomic and molecular data we produce is incorporated into databases and model atmosphere codes, benefiting astronomers worldwide in addition to those in the UK. The new laboratory data we provide to the astronomical community means that analyses of expensively obtained modern astrophysical spectra will no longer be limited by the quality and quantity of atomic (or molecular) data used in their analyses. In addition to the program of atomic data measurements, we plan a new project of high resolution molecular spectroscopy of SO2 which involves low temperature measurements in the UV, to yield molecular data urgently needed for studies of volcanically active Io, a moon of Jupiter.