用MILES进行演化恒星星族合成。第一部分：基本模型和新的线指标体系
Evolutionary Stellar Population Synthesis with MILES. Part I: The Base Models and a New Line Index System
摘要：
[摘要]。我们提出了单年龄，单金属丰度恒星星族（SSP）覆盖的光学范围内的分辨率为2.3A（FWHM）的SED。这些SED构成了我们的基础模型，因为它们将标度太阳等时线与MILES经验恒星库相结合，后者遵循太阳邻域的化学演化模式。这些模型尽可能地依赖于经验成分，不仅依赖于恒星光谱，还依赖于广泛的光度库。MILES的前所未有的恒星参数覆盖范围使我们能够安全地将我们的光学SSP SED预测从中期扩展到非常古老的年龄区域，并且SSP的金属丰度覆盖范围从超太阳到[M/H]=-2.3。具有如此低金属丰度的SSP对于球状星团的研究特别有用。观测到的光谱可以通过全谱拟合或谱线强度来研究。对于后者，我们提出了一个新的线索引系统（LIS），以避免与流行的舔/IDS系统的内在不确定性，并提供更合适的，统一的，光谱分辨率。除了作为波长函数的恒定分辨率外，该系统还基于通量校准光谱。数据可以在三种不同的分辨率下进行分析：5A，8.4A和14A（FWHM），这三种分辨率分别适用于研究球状星团，中低质量星系和大质量星系。提供了将当前Lick/IDS线折射率测量值转换为新系统的多项式。在www.example.com上可获得具有一套在线工具的网页，以促进光谱的处理和转换。
英文摘要：
[Abridged]. We present SEDs for single-age, single-metallicity stellar populations (SSPs) covering the optical range at resolution 2.3A (FWHM). These SEDs constitute our base models, as they combine scaled-solar isochrones with MILES empirical stellar library, which follows the chemical evolution pattern of the solar neighbourhood. The models rely as much as possible on empirical ingredients, not just on the stellar spectra, but also on extensive photometric libraries. The unprecedented stellar parameter coverage of MILES allowed us to safely extend our optical SSP SED predictions from intermediate- to very-old age regimes, and the metallicity coverage of the SSPs from super-solar to [M/H]=-2.3. SSPs with such low metallicities are particularly useful for globular cluster studies. Observed spectra can be studied by means of full spectrum fitting or line-strengths. For the latter we propose a new Line Index System (LIS) to avoid the intrinsic uncertainties associated with the popular Lick/IDS system and provide more appropriate, uniform, spectral resolution. Apart from constant resolution as function of wavelength the system is also based on flux-calibrated spectra. Data can be analyzed at three different resolutions: 5A, 8.4A and 14A (FWHM), which are appropriate for studying globular cluster, low and intermediate-mass galaxies, and massive galaxies, respectively. Polynomials to transform current Lick/IDS line index measurements to the new system are provided. A web-page with a suite of on-line tools to facilitate the handling and transformation of the spectra is available at http://miles.iac.es.
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