The effect of helium-enhanced stellar populations on the ultraviolet-upturn phenomenon of early-type galaxies

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Abstract

Recent observations and modeling of globular clusters (GCs) with multiple populations strongly indicate the presence of super-helium-rich subpopulations in old stellar systems. Motivated by this, we have constructed new population synthesis models with and without helium-enhanced subpopulations to investigate their impact on the UV-upturn phenomenon of quiescent early-type galaxies (ETGs). We find that our models with helium-enhanced subpopulations can naturally reproduce the strong UV-upturns observed in giant elliptical galaxies assuming an age similar to that of old GCs in the Milky Way. The major source of far-UV (FUV) flux, in this model, is relatively metal-poor and helium-enhanced hot horizontal-branch stars and their progeny. The Burstein etal. relation of the FUV - V color with metallicity is also explained either by the variation of the fraction of helium-enhanced subpopulations or by the spread in mean age of stellar populations in ETGs.

Original languageEnglish
Article numberL45
JournalAstrophysical Journal Letters
Volume740
Issue number2
DOIs
Publication statusPublished - 2011 Oct 20

Fingerprint

helium
subpopulation
galaxies
globular clusters
horizontal branch stars
progeny
stellar systems
hot stars
elliptical galaxies
metallicity
effect
color
metal
synthesis
metals
modeling

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

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title = "The effect of helium-enhanced stellar populations on the ultraviolet-upturn phenomenon of early-type galaxies",
abstract = "Recent observations and modeling of globular clusters (GCs) with multiple populations strongly indicate the presence of super-helium-rich subpopulations in old stellar systems. Motivated by this, we have constructed new population synthesis models with and without helium-enhanced subpopulations to investigate their impact on the UV-upturn phenomenon of quiescent early-type galaxies (ETGs). We find that our models with helium-enhanced subpopulations can naturally reproduce the strong UV-upturns observed in giant elliptical galaxies assuming an age similar to that of old GCs in the Milky Way. The major source of far-UV (FUV) flux, in this model, is relatively metal-poor and helium-enhanced hot horizontal-branch stars and their progeny. The Burstein etal. relation of the FUV - V color with metallicity is also explained either by the variation of the fraction of helium-enhanced subpopulations or by the spread in mean age of stellar populations in ETGs.",
author = "Chul Chung and Yoon, {Suk Jin} and Lee, {Young Wook}",
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T1 - The effect of helium-enhanced stellar populations on the ultraviolet-upturn phenomenon of early-type galaxies

AU - Chung, Chul

AU - Yoon, Suk Jin

AU - Lee, Young Wook

PY - 2011/10/20

Y1 - 2011/10/20

N2 - Recent observations and modeling of globular clusters (GCs) with multiple populations strongly indicate the presence of super-helium-rich subpopulations in old stellar systems. Motivated by this, we have constructed new population synthesis models with and without helium-enhanced subpopulations to investigate their impact on the UV-upturn phenomenon of quiescent early-type galaxies (ETGs). We find that our models with helium-enhanced subpopulations can naturally reproduce the strong UV-upturns observed in giant elliptical galaxies assuming an age similar to that of old GCs in the Milky Way. The major source of far-UV (FUV) flux, in this model, is relatively metal-poor and helium-enhanced hot horizontal-branch stars and their progeny. The Burstein etal. relation of the FUV - V color with metallicity is also explained either by the variation of the fraction of helium-enhanced subpopulations or by the spread in mean age of stellar populations in ETGs.

AB - Recent observations and modeling of globular clusters (GCs) with multiple populations strongly indicate the presence of super-helium-rich subpopulations in old stellar systems. Motivated by this, we have constructed new population synthesis models with and without helium-enhanced subpopulations to investigate their impact on the UV-upturn phenomenon of quiescent early-type galaxies (ETGs). We find that our models with helium-enhanced subpopulations can naturally reproduce the strong UV-upturns observed in giant elliptical galaxies assuming an age similar to that of old GCs in the Milky Way. The major source of far-UV (FUV) flux, in this model, is relatively metal-poor and helium-enhanced hot horizontal-branch stars and their progeny. The Burstein etal. relation of the FUV - V color with metallicity is also explained either by the variation of the fraction of helium-enhanced subpopulations or by the spread in mean age of stellar populations in ETGs.

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