Tests of model predictions for the response of stellar spectra and absorption line indices to element abundance variations
arXiv:1307.4578 · doi:10.1093/mnras/stt1283
Abstract
To analyse stellar populations in galaxies a widely used method is to apply theoretically derived responses of stellar spectra and line indices to element abundance variations, hereafter referred to as response functions. These are applied in a differential way, to base models, in order to generate spectra or indices with different abundance patterns. In this paper sets of such response functions for three different stellar evolutionary stages are tested with new empirical [Mg/Fe] abundance data for the MILES stellar spectral library. Recent theoretical models and observations are used to investigate the effects of [Fe/H], [Mg/H] and overall [Z/H] on spectra, via ratios of spectra for similar stars. Global effects of changes in abundance patterns are investigated empirically through direct comparisons of similar stars from the MILES library, highlighting the impact of abundance effects in the blue part of the spectrum, particularly for lower temperature stars. It is found that the relative behaviour of iron sensitive line indices are generally well predicted by response functions, whereas Balmer line indices are not. Other indices tend to show large scatter about the predicted mean relations. Implications for element abundance and age studies in stellar populations are discussed and ways forward are suggested to improve the match with behaviours of spectra and line strength indices observed in real stars.
26 pages, 15 figures, 9 tables, accepted for publication in MNRAS
References in corpus (53)
- MILES: A Medium resolution INT Library of Empirical Spectra
- Galactic Chemical Evolution: Hydrogen Through Zinc
- Galactic chemical evolution: Carbon through Zinc
- Stellar population models of Lick indices with variable element abundance ratios
- Evolutionary Stellar Population Synthesis with MILES. Part I: The Base Models and a New Line Index System
- An updated MILES stellar library and stellar population models
- Old Stellar Populations. VI. Absorption-Line Spectra of Galaxy Nuclei and Globular Clusters
- The Stellar Population Histories of Local Early-Type Galaxies. I. Population Parameters
- alpha-, r-, and s-process element trends in the Galactic thin and thick disks
- Rates and properties of type Ia supernovae as a function of mass and star-formation in their host galaxies
- A library of high resolution synthetic stellar spectra from 300nm to 1.8 micron with solar and alpha-enhanced composition
- An extensive library of 2500-10500 Ang synthetic spectra
- Population Synthesis in the Blue IV: Accurate Model Predictions for Lick Indices and UBV Colors in Single Stellar Populations
- Medium-resolution Isaac Newton Telescope library of empirical spectra - II. The stellar atmospheric parameters
- The supernova delay time distribution in galaxy clusters and implications for Type-Ia progenitors and metal enrichment
- Chemical abundance analysis of the Open Clusters Cr110, NGC2099 (M37), NGC2420, NGC7789 and M67 (NGC2682)
- A new chemo-evolutionary population synthesis model for early-type galaxies. II: Observations and Results
- Oxygen Abundances in Nearby Stars. Clues to the formation and evolution of the Galactic disk
- Chemical Clues on the Formation of Planetary Systems: C/O vs Mg/Si for HARPS GTO Sample
- Accurate fundamental parameters for Lower Main Sequence Stars
- A comparison of stellar populations in galaxy populations across a wide range of Hubble types
- Spectral models for solar-scaled and alpha-enhanced stellar populations
- Chemical abundances of 451 stars from the HARPS GTO planet search program: Thin disc, thick disc, and planets
- Abundance trends in kinematical groups of the Milky Way's disk
- Measuring Ages and Elemental Abundances from Unresolved Stellar Populations: Fe, Mg, C, N, and Ca
- The sensitivity of Lick indices to abundance variations
- Color transformations and bolometric corrections for Galactic halo stars: alpha-enhanced vs scaled-solar results
- C, S, Zn and Cu abundances in planet-harbouring stars
- A large stellar evolution database for population synthesis studies. IV. Integrated properties and spectra
- Oxygen abundances in planet-harbouring stars. Comparison of different abundance indicators
- Differential stellar population models: how to reliably measure [Fe/H] and [alpha/Fe] in galaxies
- Carbon and Oxygen in Nearby Stars: Keys to Protoplanetary Disk Chemistry
- An optimized H_βindex for disentangling stellar population ages
- Homogeneous photometry and metal abundances for a large sample of Hipparcos metal-poor stars
- Stellar Population Models and Individual Element Abundances II: Stellar Spectra and Integrated Light Models
- Analysis of old very metal rich stars in the solar neighbourhood
- Stellar Populations of Elliptical Galaxies in the Local Universe
- Element abundances in the stars of the MILES spectral library: the Mg/Fe ratio
- The Evolution of Oxygen and Magnesium in the Bulge and Disk of the Milky Way
- The Age, Metallicity and Alpha-Element Abundance of Galactic Globular Clusters from Single Stellar Population Models
- Balmer and Metal Absorption Feature Gradients in M32
- Stellar populations, neutral hydrogen and ionised gas in field early-type galaxies
- Homogeneous photospheric parameters and C abundances in G and K nearby stars with and without planets
- Abundance ratios in red-sequence galaxies over a wide mass range: The "X-planes" for magnesium, calcium, carbon and nitrogen
- Chemical abundance ratios of galactic globular clusters from modelling integrated light spectroscopy
- Optical/near-infrared colours of early-type galaxies and constraints on their star formation histories
- Early-type galaxies in the Coma cluster: a new piece in the calcium puzzle
- Optical and near infra-red colours as a discriminant of the age and metallicity of stellar populations
- A New Definition for the Ca4227 Feature: Is Calcium Really Underabundant in Early-type Galaxies?
- Mg and TiO spectral features at the near-IR: Spectrophotometric index definitions and empirical calibrations
- Bimodality in low luminosity E and S0 galaxies
- Nature vs. nurture in the low-density environment: structure and evolution of early-type dwarf galaxies in poor groups
- Comparison of Alpha-Element Enhanced Simple Stellar Population Models with Milky Way Globular Clusters
Cited by in corpus (16)
- Evolutionary stellar population synthesis with MILES - II. Scaled-solar and α-enhanced models
- Metal-rich, Metal-poor: Updated Stellar Population Models for Old Stellar Systems
- Abundance patterns in early-type galaxies: is there a 'knee' in the [Fe/H] vs. [alpha/Fe] relation?
- To use or not to use synthetic stellar spectra in population synthesis models?
- The Initial Mass Function of Early-type Galaxies: no correlation with [Mg/Fe]
- sMILES SSPs: A Library of Semi-Empirical MILES Stellar Population Models with Variable [/Fe] Abundances
- sMILES: A Library of Semi-Empirical MILES Stellar Spectra with Variable [/Fe] Abundances
- Testing Stellar Population Fitting Ingredients with Globular Clusters I: Stellar Libraries
- Using Star Clusters as Tracers of Star Formation and Chemical Evolution: the Chemical Enrichment History of the Large Magellanic Cloud
- MUSE library of stellar spectra
- The FEROS--Lick/SDSS observational database of spectral indices of FGK stars for stellar population studies
- Nonlinear Color--Metallicity Relations of Globular Clusters. VI. On Calcium II Triplet Based Metallicities of Globular Clusters in Early-type Galaxies
- The Imprint of Element Abundance Patterns on Quiescent Galaxy SEDs
- Measuring the stellar population parameters of the early-type galaxy NGC 3923 -- The challenging measurement of the initial mass function
- Eight luminous early-type galaxies in nearby pairs and sparse groups I. Stellar populations spatially analysed
- The stellar populations in the low luminosity, early-type galaxy NGC59