近邻星系恒星形成区光谱观测研究

Spectroscopic Observations of the Star Formation Regions in Nearby Galaxies

近年来随着国际8—10iTI口径望远镜数目的不断增加，41TI及以下口径望远镜已成为中小型望远镜．如何利用中、小口径望远镜做出有影响的科学成果，须做到“有所为，有所不为”．为此，自2013年开始针对国家天文台2．16m望远镜推出了重点课题支持计划．介绍的“近邻星系恒星形成区光谱观测研究”为2．16rfl望远镜支持的3个重点课题之一．它将利用2．16m望远镜3yr、每年30个暗夜或灰夜的观测时间，开展20个近邻、大星系中多个恒星形成区、平行星系主轴方向和垂直主轴方向的光谱观测，获得一个有显示度的、科学意义重要的近邻星系恒星形成区和径向分布的光谱样本．同时该课题还利用6．5m多镜面望远镜（MMT）的观测时间，开展近邻、特大星系的恒星形成区的光谱观测．利用2．16m望远镜和MMT望远镜观测得到的星系不同区域的光谱数据，结合已有的紫外、光学、红外波段宽带滤光片数据和BATCfBeijing-Arizona-Taiwan．Connecticut）15个中带滤光片数据，可开展星系尘埃消光、恒星形成率、金属丰度和星族特性二维分布等方面的研究；开展星系二维特性和星系形态、星系环境关系的研究．将介绍这个重点课题的科学意义、星系样本的选取、光谱观测策略和星系NGC2403的光谱观测和初步研究结果．

During the late 1990s and the first decade of the 21st century, the 8 - 10 m scale ground-based telescopes are helping astronomers learn much more about how galaxies develop. The existing 2 - 4 m scale telescopes become less important for astrophysical researches. To use the existing 2 - 4 m scale telescopes to address important issues in cosmology and extragalactic and galactic astronomy, we have to consider very carefully which kind of things we can do, and which we can not. For this reason, the Time Allocation Committee （TAC） of the National Astronomical Observatories of China （NAOC） 2.16 m telescope decides to support some key projects since 2013. Nearby galaxies supply us with the opportunity to study galaxy dynamics and star formation on large scales, yet are close enough to reveal the details. Star formation regions in nearby galaxies provide an excellent laboratory to study the star formation processes, the evolution of massive stars, and the properties of the surrounding interstellar medium. A wealth of information can be obtained from the spectral analysis of the bright emission lines and the stellar continuum. Considering these, we proposed a long-term project ＂Spectro- scopic Observations of the Star Formation Regions in Nearby Galaxies＂, and it becomes the key project of the NAOC 2.16 m telescope since 2013, supported with 30 dark/grey nights per year. The primary goal of this project is to observe the spectroscopy of star formation regions in 20 nearby galaxies, with the NAOC 2.16 m telescope and the Hectospec/MMT （Multiple Mirror Telescope） multifiber spectrograph by Telescope Access Program （TAP）. With the spectra of a large sample of star formation regions, combining multi-wavelength data from UV to IR, we can investigate, understand, and quantify the nature of the deviation from the starbursts＇ IRX-γ （the IR/UV ratio ＂IRX＂ versus the UV color ） correlation. It will be important for a better understanding of the interaction of dust and radiation specifically in nearby galaxies, but it also has direct consequences for our understanding and interpretation of galaxy evolution in a general context. As the first paper of this project, we describe the sample and scientific objectives, review the observation, and present initial results in this paper. We have obtained spectrophotometric data for 80 star formation regions in the spiral galaxy NGC 2403, and have determined the radial gas-phase oxygen abundance and dust extinction gradient of NGC 2403.