sMILES: a library of semi-empirical MILES stellar spectra with variable [<i>α</i>/Fe] abundances

Knowles, Adam Thomas; Sansom, A. E.; Prieto, C. Allende; Vazdekis, Alexandre

doi:10.1093/mnras/stab1001

Cited by 17 publications

(32 citation statements)

References 101 publications

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“…• Theoretical stars from Knowles (2019): We included a small set of theoretical stellar models, generated using the same method presented in Knowles et al (2021). In summary, these models are computed using ATLAS9 (Kurucz 1993), with publicly available 3 opacity distribution functions described in Mészáros et al 2012.…”

Section: Stellar Librariesmentioning

confidence: 99%

“…The models here adopt Asplund et al (2005) solar abundances and a microturbulent velocity of 2 km s −1 . We direct interested readers to Knowles (2019) and Knowles et al (2021) for further details. The star models in this work have effective temperatures of 3500, 3750 and 4000 K, for log 𝑔=1.5, [M/H]=[𝛼/M]=0.0 and two different carbon abundances; scaled-solar ([C/Fe]=0.0) and enhanced ([C/Fe]=0.25).…”

Section: Stellar Librariesmentioning

confidence: 99%

“…Unfortunately, carbon abundances for giant stars in the IRTF library have not been measured yet. Hence, we relied on theoretical C-enhanced stars from Knowles (2019) to see if an enhancement in carbon abundance might explain the difference between CO line-strengths in the two CO sequences. In Fig.…”

Section: What Is Driving the Empirical Corrections?mentioning

confidence: 99%

“…In each panel, the CO line-strength for the XSG stack is marked with a dashed-red line. The light green arrows mark the increase caused by a [C/Fe] enhancement of 0.25 dex, from the theoretical stars ofKnowles (2019), all having solar metallicity and log 𝑔 = 1.5.…”

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confidence: 99%

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Strong CO absorption features in massive ETGs

Eftekhari¹,

Barbera²,

Vazdekis³

et al. 2022

Monthly Notices of the Royal Astronomical Society

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Massive Early-Type Galaxies (ETG) in the local Universe are believed to be the most mature stage of galaxy evolution. Their stellar population content reveals the evolutionary history of these galaxies. However, while state-of-the-art Stellar Population Synthesis (SPS) models provide an accurate description of observed galaxy spectra in the optical range, the modelling in the Near-Infrared (NIR) is still in its infancy. Here we focus on NIR CO absorption features to show, in a systematic and comprehensive manner, that for massive ETGs, all CO indices, from H through to K band, are significantly stronger than currently predicted by SPS models. We explore and discuss several possible explanations of this ‘CO mismatch’, including the effect of intermediate-age, AGB-dominated, stellar populations, high metallicity populations, non-solar abundance ratios and the initial mass function. While none of these effects is able to reconcile models and observations, we show that ad-hoc ‘empirical’ corrections, taking into account the effect of CO-strong giant stars in the low-temperature regime, provide model predictions that are closer to the observations. Our analysis points to the effect of carbon abundance as the most likely explanation of NIR CO line-strengths, indicating possible routes for improving the SPS models in the NIR.

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Section: Stellar Librariesmentioning

confidence: 99%

Section: Stellar Librariesmentioning

confidence: 99%

Section: What Is Driving the Empirical Corrections?mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Strong CO absorption features in massive ETGs

Eftekhari¹,

Barbera²,

Vazdekis³

et al. 2022

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

show abstract

Section: Stellar Librariesmentioning

confidence: 99%

Strong CO Absorption Features in Massive ETGs

Eftekhari,

La Barbera,

Vazdekis

et al. 2022

Preprint

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Massive Early-Type Galaxies (ETG) in the local Universe are believed to be the most mature stage of galaxy evolution. Their stellar population content reveals the evolutionary history of these galaxies. However, while state-of-the-art Stellar Population Synthesis (SPS) models provide an accurate description of observed galaxy spectra in the optical range, the modelling in the Near-Infrared (NIR) is still in its infancy. Here we focus on NIR CO absorption features to show, in a systematic and comprehensive manner, that for massive ETGs, all CO indices, from H through to K band, are significantly stronger than currently predicted by SPS models. We explore and discuss several possible explanations of this "CO mismatch", including the effect of intermediateage, AGB-dominated, stellar populations, high metallicity populations, non-solar abundance ratios and the initial mass function. While none of these effects is able to reconcile models and observations, we show that ad-hoc "empirical" corrections, taking into account the effect of CO-strong giant stars in the low-temperature regime, provide model predictions that are closer to the observations. Our analysis points to the effect of carbon abundance as the most likely explanation of NIR CO line-strengths, indicating possible routes for improving the SPS models in the NIR.

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Chemical characterisation of the X-shooter Spectral Library (XSL): [Mg/Fe] and [Ca/Fe] abundances

Santos-Peral

Sánchez-Blázquez

Vazdekis

et al. 2023

A&A

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Context. The X-shooter Spectral Library (XSL) is a large empirical stellar library used as a benchmark for the development of stellar population models. The inclusion of α-element abundances is crucial to disentangling the chemical evolution of any stellar system. Aims. The aim of this paper is to provide a catalogue of high-precision, accurate magnesium and calcium abundances from a wide variety of stars that are well distributed in the Hertzsprung-Russell (HR) diagram. Methods. We originally performed an analysis of the derived Mg and Ca abundances for medium-resolution spectra of 611 stars from the XSL Data Release 2. For this purpose, we used the GAUGUIN automated abundance estimation code to fit the ultravioletblue (UVB) and visible (VIS) spectra. We tested the consistency of the atmospheric parameters and chemical abundances with the Gaia DR3 and the AMBRE Project datasets. Results. We finally obtained precise [Mg/Fe] and [Ca/Fe] abundances for 192 and 217 stars, respectively, from which 174 stars have measurements in both elements. The stars cover a broad effective temperature range of 4000 < T eff < 6500 K, surface gravity of 0.3 < log(g) < 4.8 cm s −2 , and metallicity of -2.5 < [Fe/H] < +0.4 dex. We find an excellent agreement with the abundance estimates from the AMBRE:HARPS and the Gaia-RVS (Radial Velocity Spectrometer) analysis. Moreover, the resulting abundances reproduce a plateau in the metal-poor regime followed by a decreasing trend even at supersolar metallicities, as predicted by Galactic chemical evolution models. Conclusions. This catalogue is suitable for improving the modelling of evolutionary stellar population models with empirical α enhancements, which could significantly contribute to the analysis of external galaxies' abundances in the near future.

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sMILES: a library of semi-empirical MILES stellar spectra with variable [α/Fe] abundances

Cited by 17 publications

References 101 publications

Strong CO absorption features in massive ETGs

Strong CO absorption features in massive ETGs

Strong CO Absorption Features in Massive ETGs

Chemical characterisation of the X-shooter Spectral Library (XSL): [Mg/Fe] and [Ca/Fe] abundances

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