A standard stellar library for evolutionary synthesis

Westera, P.; Lejeune, T.; Buser, R.; Cuisinier, F.; Bruzual, G.

doi:10.1051/0004-6361:20011493

Cited by 252 publications

(300 citation statements)

References 77 publications

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“…We use the standard BaSeL library of synthetic stellar spectra, worked out by Lejeune et al (1997Lejeune et al ( , 1998 and Westera et al (2002). This library is based on the grids of model atmospheres spectra of Bessell et al (1989Bessell et al ( , 1991, Fluks et al (1994), andKurucz (1995, priv.…”

Section: Methodsmentioning

confidence: 99%

Multiwavelength flux variations induced by stellar magnetic activity: effects on planetary transits

Ballerini

Micela

Lanza

et al. 2012

A&A

102

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Stellar magnetic activity is a source of noise in the study of the transits of extrasolar planets. It induces flux variations that significantly affect the transit depth determination and the derivations of planetary and stellar parameters. Furthermore, the colour dependence of stellar activity may significantly influence the characterization of planetary atmospheres. Here we present a systematic approach to quantify the corresponding stellar flux variations as a function of wavelength bands. We consider a star with spots covering a given fraction of its disc and model the variability in both the UBVRIJHK photometric system and the Spitzer/IRAC wavebands for dwarf stars from G to M spectral types. We compare activity-induced flux variations in different passbands with planetary transits and quantify how they affect the determination of the planetary radius and the analysis of the transmission spectroscopy in the study of planetary atmospheres. We suggest that the monitoring of the systems by using broad-band photometry, from visible to infrared, helps us to constrain activity effects. The ratio of the relative variations in the stellar fluxes at short wavelength optical bands (e.g., U or B) to near-infrared ones (e.g., J or K) can be used to distinguish starspot brightness dips from planetary transits in a stellar light curve. In addition to the perturbations in the measurement of the planetary radius, we find that starspots can affect the determinations of both the relative semimajor axis and the inclination of the planetary orbit, which have a significant impact on the derivation of the stellar density from the transit light curves.

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Section: Methodsmentioning

confidence: 99%

Multiwavelength flux variations induced by stellar magnetic activity: effects on planetary transits

Ballerini

Micela

Lanza

et al. 2012

A&A

102

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“…In the following we will consider the empirical BCs by Worthey & Lee (2011) that we have already used in the previous plots, plus the semiempirical BCs by Westera et al (2002) and the theoretical results from the MARCS (Gustafsson et al 2008) and PHOENIX (Dotter et al 2008) model atmospheres 6 . The Westera et al (2002) BCs do not include metallicities [M/H] below −2.0, whilst the MARCS results do not include surface gravities log(g)<0.0, therefore they do not cover the oldest solar metallicity TRGBs and the supersolar ones. Figure 8 and 9 compare the VI and JK absolute magnitudecolour calibrations obtained with our best choice theoretical models and these sets of BCs.…”

Section: Theoretical Uncertainties On Trgb Distances: Bolometric Corrmentioning

confidence: 99%

“…Above (V − I) TRGB ∼4.0 the slopes of the magnitude-colour relationships are radically different. The Westera et al (2002) BC produce sizable discontinuities in the magnitude-colour relationship due to the stronger dependence of the BC to the I-band on metallicity, compared to the other sets of BCs.…”

Section: Theoretical Uncertainties On Trgb Distances: Bolometric Corrmentioning

confidence: 99%

The brightness of the red giant branch tip

Serenelli

Weiß

Cassisi

et al. 2017

A&A

107

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Context. The brightness of the tip of the Red Giant Branch is a useful reference quantity for several fields of astrophysics. An accurate theoretical prediction is needed for such purposes. Aims. We intend to provide a solid theoretical prediction for it, valid for a reference set of standard physical assumptions, and mostly independent of numerical details. Methods. We examine the dependence on physical assumptions and numerical details, for a wide range of metallicities and masses, and based on two different stellar evolution codes. We adjust differences between the codes to treat the physics as identical as possible. After we have succeeded in reproducing the tip brightness between the codes, we present a reference set of models based on the most up to date physical inputs, but neglecting microscopic diffusion, and convert theoretical luminosities to observed infrared colours suitable for observations of resolved populations of stars and include analytic fits to facilitate their use. Results. We find that consistent use of updated nuclear reactions, including an appropriate treatment of the electron screening effects, and careful time-stepping on the upper red giant branch are the most important aspects to bring initially discrepant theoretical values into agreement. Small, but visible differences remain unexplained for very low metallicities and mass values at and above 1.2 M ⊙ , corresponding to ages younger than 4 Gyr. The colour transformations introduce larger uncertainties than the differences between the two stellar evolution codes. Conclusions. We demonstrate that careful stellar modeling allows an accurate prediction for the luminosity of the Red Giant Branch tip. Differences to empirically determined brightnesses may result either from insufficient colour transformations or from deficits in the constitutional physics. We present the best-tested theoretical reference values to date.

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“…The SSP models given by BC03 span a wide range of wavelength (91 Å−160 μm, N = 6900), age (0-20 Gyr, N = 221), and metallicity Z (0.0001-0.05, N = 6). These models mainly use the STELIB/BaSeL3.1 libraries (Le Borgne et al 2003;Lejeune et al 1997Lejeune et al , 1998Westera et al 2002, and references therein) with resolutions of 3 Å (FWHM) from 3200 Å to 9500 Å, and 20 Å (FWHM) elsewhere. In addition, BC03 provides models that rely on STELIB/Pickles libraries (Pickles 1998).…”

Section: Bc 03mentioning

confidence: 99%

Comparing six evolutionary population synthesis models by performing spectral synthesis for galaxies

Chen

Liang

Hammer

et al. 2010

A&A

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Aims. We compare six popularly used evolutionary population synthesis (EPS) models by fitting the full optical spectra of six representative types of galaxies (star-forming and composite galaxies, Seyfert 2s, LINERs, E+A, and early-type galaxies) taken from the Sloan Digital Sky Survey (SDSS). We explore the dependence of stellar population synthesis results on the main ingredients of the EPS models and study whether there is an age sequence among these types of galaxies. Methods. We use the simple stellar populations (SSPs) of each EPS model and the software STARLIGHT to perform our fits. Firstly, we explore the dependence of stellar population synthesis on EPS models by fixing the age, metallicity, and initial mass function (IMF) to construct a standard SSP group. We then use the standard SSP group of each EPS model (BC03, CB07, Ma05, GALEV, GRASIL, and Vazdekis/Miles) to fit the spectra of star-forming and E+A galaxies. Secondly, we fix the IMF and alter the age and metallicity to construct eight additional SSP groups. We then use these SSP groups to fit the spectra of star-forming and E+A galaxies to verify the effects of age and metallicity on stellar populations. Finally, we study the effect of stellar evolution tracks and stellar spectral libraries on our results, and present a possible age sequence among these types of galaxies. Results. Using different EPS models, the numerical values of contributing light fractions obviously change, even though the dominant populations are unaltered. The stellar population synthesis does depend on the selection of age and metallicity, but does not depend significantly on the stellar evolution track. The importance of young populations decreases from star-forming, composite, Seyfert 2, LINER, to early-type galaxies, and the properties of E+A galaxies are between composite galaxies and Seyfert 2s in most cases. Conclusions. Different EPS models infer different stellar population parameters, so that it is not reasonable to directly compare stellar populations estimated from different EPS models. To obtain reliable results, we should use the same EPS model to derive the parameter values that we compare.

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A standard stellar library for evolutionary synthesis

Cited by 252 publications

References 77 publications

Multiwavelength flux variations induced by stellar magnetic activity: effects on planetary transits

Multiwavelength flux variations induced by stellar magnetic activity: effects on planetary transits

The brightness of the red giant branch tip

Comparing six evolutionary population synthesis models by performing spectral synthesis for galaxies

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