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Higher-order Balmer line indices in alpha/Fe-enhanced stellar population models

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Higher-order Balmer line indices in alpha/Fe-enhanced stellar population models. / Thomas, D; Maraston, Claudia; Korn, Andreas.

In: Monthly Notices of the Royal Astronomical Society, Vol. 351, No. 1, 11.07.2004, p. L19-L23.

Research output: Contribution to journalArticle

Harvard

Thomas, D, Maraston, C & Korn, A 2004, 'Higher-order Balmer line indices in alpha/Fe-enhanced stellar population models', Monthly Notices of the Royal Astronomical Society, vol. 351, no. 1, pp. L19-L23. https://doi.org/10.1111/j.1365-2966.2004.07944.x

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Author

Thomas, D ; Maraston, Claudia ; Korn, Andreas. / Higher-order Balmer line indices in alpha/Fe-enhanced stellar population models. In: Monthly Notices of the Royal Astronomical Society. 2004 ; Vol. 351, No. 1. pp. L19-L23.

Bibtex

@article{406bdedb4e164a7388dcebc05d236815,
title = "Higher-order Balmer line indices in alpha/Fe-enhanced stellar population models",
abstract = "We have computed the higher-order Balmer absorption line indices Hγ and Hδ for stellar population models with variable element ratios. The response of these indices to abundance ratio variations is taken from detailed line formation and model atmosphere calculations. We find that Hγ and Hδ, unlike Hβ, are very sensitive to α/Fe ratio changes at super-solar metallicities. Both line indices increase significantly with increasing α/Fe ratio. This effect cannot be neglected when these line indices are used to derive the ages of metal-rich, unresolved stellar populations such as early-type galaxies. We re-analyze the elliptical galaxy sample of Kuntschner, and show that consistent age estimates from Hβ and Hγ are obtained only if the effect of α/Fe enhancement on Hγ is taken into account in the models. This result rectifies a problem currently present in the literature, namely that Hγ and Hδ have up to now led to significantly younger ages for early-type galaxies than Hβ. Our work particularly impacts on the interpretation of intermediate- to high-redshift data, for which only the higher-order Balmer lines are accessible observationally.",
keywords = "stars : abundances, galaxy : abundances, globular clusters : general, galaxies : elliptical and lenticular, cD, galaxies : stellar content",
author = "D Thomas and Claudia Maraston and Andreas Korn",
year = "2004",
month = "7",
day = "11",
doi = "10.1111/j.1365-2966.2004.07944.x",
language = "English",
volume = "351",
pages = "L19--L23",
journal = "MNRAS",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "1",

}

RIS

TY - JOUR

T1 - Higher-order Balmer line indices in alpha/Fe-enhanced stellar population models

AU - Thomas, D

AU - Maraston, Claudia

AU - Korn, Andreas

PY - 2004/7/11

Y1 - 2004/7/11

N2 - We have computed the higher-order Balmer absorption line indices Hγ and Hδ for stellar population models with variable element ratios. The response of these indices to abundance ratio variations is taken from detailed line formation and model atmosphere calculations. We find that Hγ and Hδ, unlike Hβ, are very sensitive to α/Fe ratio changes at super-solar metallicities. Both line indices increase significantly with increasing α/Fe ratio. This effect cannot be neglected when these line indices are used to derive the ages of metal-rich, unresolved stellar populations such as early-type galaxies. We re-analyze the elliptical galaxy sample of Kuntschner, and show that consistent age estimates from Hβ and Hγ are obtained only if the effect of α/Fe enhancement on Hγ is taken into account in the models. This result rectifies a problem currently present in the literature, namely that Hγ and Hδ have up to now led to significantly younger ages for early-type galaxies than Hβ. Our work particularly impacts on the interpretation of intermediate- to high-redshift data, for which only the higher-order Balmer lines are accessible observationally.

AB - We have computed the higher-order Balmer absorption line indices Hγ and Hδ for stellar population models with variable element ratios. The response of these indices to abundance ratio variations is taken from detailed line formation and model atmosphere calculations. We find that Hγ and Hδ, unlike Hβ, are very sensitive to α/Fe ratio changes at super-solar metallicities. Both line indices increase significantly with increasing α/Fe ratio. This effect cannot be neglected when these line indices are used to derive the ages of metal-rich, unresolved stellar populations such as early-type galaxies. We re-analyze the elliptical galaxy sample of Kuntschner, and show that consistent age estimates from Hβ and Hγ are obtained only if the effect of α/Fe enhancement on Hγ is taken into account in the models. This result rectifies a problem currently present in the literature, namely that Hγ and Hδ have up to now led to significantly younger ages for early-type galaxies than Hβ. Our work particularly impacts on the interpretation of intermediate- to high-redshift data, for which only the higher-order Balmer lines are accessible observationally.

KW - stars : abundances

KW - galaxy : abundances

KW - globular clusters : general

KW - galaxies : elliptical and lenticular, cD

KW - galaxies : stellar content

U2 - 10.1111/j.1365-2966.2004.07944.x

DO - 10.1111/j.1365-2966.2004.07944.x

M3 - Article

VL - 351

SP - L19-L23

JO - MNRAS

JF - MNRAS

SN - 0035-8711

IS - 1

ER -

ID: 1795516