Laboratory Astrophysics: new atomic and molecular data for astrophysics applications

摘要：这项研究是一项实验室研究方案，目的是为天体物理学应用提供新的精确原子和分子数据。帝国理工学院实验室光谱学小组在使用我们的高分辨率傅里叶变换光谱仪进行高分辨率光谱研究方面有着悠久的历史，并通过国际合作进行研究。在许多情况下，对天体物理物体的研究涉及光谱分析，这需要原子和分子数据库对其进行可靠的解释。地面和空间望远镜上的新的高分辨率光谱仪使天文学家能够观察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。特别重要的是铁族元素（Ti、V、Cr、Mn、Fe、Co、Ni）的丰富的富线光谱。虽然近年来原子数据有了很大的改进，但仍然存在关键的缺失数据，这些数据不完整或不准确，并且在中性和单电离物质的红外光谱的情况下，通常完全缺失。我们将使用我们独特的可见-紫外傅里叶变换（FT）光谱仪在帝国理工学院和红外-可见FT光谱仪在NIST（国家标准与技术研究所，美国）和隆德大学（瑞典），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宽光谱范围内以高分辨率测量特定物种的光谱。我们将专注于测量导致至少数量级的改善波长精度，原子能级，振子强度（需要确定天体物理对象中元素的丰度），和超精细结构。天文学家利用这些原子数据分析天体物理光谱。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学项目，例如：太阳光球和低金属量恒星的化学组成，银河系化学演化研究，低质量恒星，褐矮星和太阳系外行星，热恒星和化学奇特恒星。除了原子数据测量计划外，我们还计划开展一个新的项目，对双原子硫进行高分辨率分子光谱分析，其中包括紫外光谱测量，以获得各种研究迫切需要的分子数据，包括：木星卫星木卫一的大气和火山羽流;木星的大气和彗星彗星。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，除了英国的天文学家之外，世界各地的天文学家也从中受益。我们向天文学界提供的新实验室数据意味着，对昂贵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。

Summary: This research is a programme of laboratory studies to give new accurate atomic and molecular data for astrophysics applications. The Imperial College laboratory spectroscopy group has a long history of high resolution spectroscopic studies using our high resolution Fourier transform spectrometers, and also through international collaborations. Studies of astrophysical objects in many cases involve analyses of spectra which require an atomic and molecular data base for their reliable interpretation. 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). Although there has been great improvement in the atomic data in recent years, there remain key missing data, that are incomplete or 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 infrared-visible FT spectrometers at NIST (National Institute Standards & Technology, USA) and Lund University (Sweden) 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: chemical composition of the solar photosphere and low metallicity stars, studies of Galactic chemical evolution, low mass stars, brown dwarfs and extra solar planets, hot stars, and chemically peculiar stars. In addition to the program of atomic data measurements, we plan a new project of high resolution molecular spectroscopy of diatomic sulphur, which involves spectroscopic measurements in the ultraviolet, to yield molecular data urgently needed for a variety of studies including: atmosphere and volcanic plumes of Io, a moon of Jupiter; the atmosphere of Jupiter, and cometary comae. 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.