Context. Absorption line indices are widely used to determine the stellar population parameters such as age and metallicity of galaxies, but it is not easy to obtain the line indices of some distant galaxies that have colours available. Aims. This paper investigates the correlations between absorption line indices and colours. Methods. A few statistical fitting methods are mainly used, via both the observational data of Sloan Digital Sky Survey and a widely used theoretical stellar population model. Results. Some correlations between widely used absorption line indices and ugriz colours are found from both observational data of early-type galaxies and a theoretical simple stellar population model. In particular, good correlations between colours and widely used absorption line indices such as Dn(4000), HgammaA, HgammaF, HdeltaA, Mg1, Mg2, and Mgb, are shown in this paper. Conclusions. Some important absorption line indices of early-type galaxies can be estimated from their colours using correlations between absorption line indices and colours. For example, age-sensitive absorption line indices can be estimated from (u-r) or (g-r) colours and metallicity-sensitive ones from (u - z) or (g - z). This is useful for studying the stellar populations of distant galaxies, especially for statistical investigations.
A new catalog of homogenised absorption line indices for Milky Way globular clusters from high-resolution integrated spectroscopy
我们对24个银河系球状星团进行了综合光谱分析。从一个核心半径的光谱观察到每个集群与高波长分辨率~2.0 A的FWHM。结合Puzia et al.（2002）和Schiavon et al.（2005）的两个现有数据集，我们构建了一个包含53个银河系球状星团的Lick光谱指数的大型数据库，这些球状星团具有广泛的金属丰度范围，-2.4 < [Fe/H] < 0.1，以及各种水平分支形态。经验指数到金属丰度的转换关系提供了20舔指数用于推导金属丰度的远程，未解决的恒星系统。
A novel data-driven approach to extract stellar population properties from galaxy spectra using absorption indices
Institute of Space Sciences (ICE, CSIC)（空间科学研究所（ICE，CSIC））；Instituto de Astrofísica de Canarias（加那利天体物理研究所）；Departamento de Astrofísica, Universidad de La Laguna（拉帕尔马大学天体物理学系）；INAF-Osservatorio Astrofisico di Arcetri（意大利国家天体物理研究所阿切特里天文台）；Department of Physics and Astronomy, University College London（伦敦大学学院物理与天文系）；Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze（佛罗伦萨大学物理与天文系）
Correcting the fiber-aperture bias affecting galaxy stellar populations in the Sloan Digital Sky Survey. Aperture corrections to absorption indices based on CALIFA integral field observations
INAF-Osservatorio Astrofisico di Arcetri（意大利国家天体物理研究所阿切特里天文台）；Dipartimento di Fisica, Università di Trento（特伦托大学物理系）
A heterogeneous set of unusual quasars selected from astrometry and broad-band photometry
Cosmic DAWN Center（宇宙DAWN中心）；Niels Bohr Institute, Copenhagen University（尼尔斯·玻尔研究所，哥本哈根大学）；Nordic Optical Telescope（北欧光学望远镜）；European Southern Observatory（欧洲南方天文台）；Department of Physics, University of Oxford（牛津大学物理系）；Centre de Recherche Astrophysique de Lyon, Université Lyon 1（里昂天体物理研究中心，里昂第一大学）；Space Physics and Astronomy Research Unit, University of Oulu（奥卢大学空间物理与天文学研究单元）；Department of Physics and Astronomy, University of Turku（图尔库大学物理与天文学系）；Department of Physics and Astronomy, Aarhus University（奥胡斯大学物理与天文学系）；Materials Science and Applied Mathematics, Malmö University（马尔默大学材料科学与应用数学）
Stellar population studies provide unique clues to constrain galaxy formation models. So far, detailed studies based on absorption line strengths have mainly focused on the optical spectral range although many diagnostic features are present in other spectral windows. In particular, the near-infrared (NIR) can provide a wealth of information about stars, such as evolved giants, that have less evident optical signatures. Due to significant advances in NIR instrumentation and extension of spectral libraries and stellar population synthesis (SPS) models to this domain, it is now possible to perfo…
