Abundance ratios in dwarf elliptical galaxies

Sen, Saffet Gokcen; Peletier, Reynier F.; Boselli, A.; Brok, Mark den; Falcón-Barroso, J.; Hensler, G.; Laurikainen, Eija; Lisker, Thorsten; Mentz, J.; Paudel, Sanjaya; Salo, H.; Sybilska, Agnieszka; Toloba, Elisa; Ven, Glenn van de; Vazdekis, Alexandre; Yeşilyaprak, Cahit

doi:10.1093/mnras/stx3254

Cited by 9 publications

(1 citation statement)

References 109 publications

(128 reference statements)

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“…These differences reflect differences in nucleosynthetic origin, with the light α-elements being produced predominantly by hydrostatic burning in massive stars, while Ca and Ti are also produced in explosive nucleosynthesis and have significant contributions from type Ia SNe (Woosley & Weaver 1995;McWilliam et al 2013;Kobayashi et al 2020). Data for the integrated light of dwarf galaxies are more scarce, but indicate Mg abundances close to scaled-solar values, thus extending the trend of decreasing [α/Fe] ratio with decreasing galaxy mass towards lower masses (Gorgas et al 1997;Şen et al 2018).…”

Section: Enrichment Time Scales and Imfmentioning

confidence: 98%

The chemical composition of globular clusters in the Local Group

Larsen

Eitner

Magg

et al. 2022

A&A

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We present detailed chemical abundance measurements for 45 globular clusters (GCs) associated with galaxies in (and, in one case, beyond) the Local Group. The measurements are based on new high-resolution integrated-light spectra of GCs in the galaxies NGC 185, NGC 205, M 31, M 33, and NGC 2403, combined with reanalysis of previously published observations of GCs in the Fornax dSph, WLM, NGC 147, NGC 6822, and the Milky Way. The GCs cover the range −2.8 < [Fe/H] < −0.1 and we determined abundances for Fe, Na, Mg, Si, Ca, Sc, Ti, Cr, Mn, Ni, Cu, Zn, Zr, Ba, and Eu. Corrections for non local thermodynamic equilibrium effects are included for Na, Mg, Ca, Ti, Mn, Fe, Ni, and Ba, building on a recently developed procedure. For several of the galaxies, our measurements provide the first quantitative constraints on the detailed composition of their metal-poor stellar populations. Overall, the GCs in different galaxies exhibit remarkably uniform abundance patterns of the α, iron-peak, and neutron-capture elements, with a dispersion of less than 0.1 dex in [α/Fe] for the full sample. There is a hint that GCs in dwarf galaxies are slightly less α-enhanced (by ∼0.04 dex on average) than those in larger galaxies. One GC in M 33 (HM33-B) resembles the most metal-rich GCs in the Fornax dSph (Fornax 4) and NGC 6822 (SC7) by having α-element abundances closer to scaled-solar values, possibly hinting at an accretion origin. A principal components analysis shows that the α-element abundances strongly correlate with those of Na, Sc, Ni, and Zn. Several GCs with [Fe/H] < −1.5 are deficient in Mg compared to other α-elements. We find no GCs with strongly enhanced r-process abundances as reported for metal-poor stars in some ultra-faint dwarfs and the Magellanic Clouds. The similarity of the abundance patterns for metal-poor GCs in different environments points to similar early enrichment histories and only allow for minor variations in the initial mass function.

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Section: Enrichment Time Scales and Imfmentioning

confidence: 98%

The chemical composition of globular clusters in the Local Group

Larsen

Eitner

Magg

et al. 2022

A&A

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Detection of young (≤20 Myr) stellar populations in apparently quenched low-mass galaxies using red spectral line indices

Lorenzo-Cáceres

Vazdekis

Falcón-Barroso

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We report on the detection of a small contribution (around and below 1% in mass) from young stellar components with ages ≤20 Myr in low-mass galaxies purposely selected from the MaNGA survey to be already-quenched systems. Among the sample of 28 galaxies, eight of them show signatures of having suffered a very recent burst of star formation. The detection has been done through the analysis of line-strength indices in the red spectral range [5700,8800] Å. The increasing contribution of red supergiants to this red regime is responsible for a deviation of the index measurements with respect to their position within the model grids in the standard spectral range [3600,5700] Å. We demonstrate that a combination of red indices, as well as a qualitative assessment of the mean luminosity-weighted underlying stellar population, is required in order to distinguish between a true superyoung population and other possible causes of this deviation, such as abundance ratio variations. Our result implies that many presumably quenched low-mass galaxies actually contain gas that is triggering some level of star formation. They have, therefore, either accreted external gas, internally recycled enough gas from stellar evolution to trigger new star formation, or they kept a gas reservoir after the harassment or stripping process that quenched them in first place. Internal processes are favoured since we find no particular trends between our non-quenched galaxies and their environment, although more work is needed to fully discard an external influence.

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

Knowles

Sansom

Prieto

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We present a new library of semi-empirical stellar spectra that is based on the empirical MILES library. A new, high resolution library of theoretical stellar spectra is generated that is specifically designed for use in stellar population studies. We test these models across their full wavelength range against other model libraries and find reasonable agreement in their predictions of spectral changes due to atmospheric α-element variations, known as differential corrections. We also test the models against the MILES and MaStar libraries of empirical stellar spectra and also find reasonable agreements, as expected from previous work. We then use the abundance pattern predictions of the new theoretical stellar spectra to differentially correct MILES spectra to create semi-empirical MILES (sMILES) star spectra with abundance patterns that differ from those present in the Milky Way. The final result is 5 families of 801 sMILES stars with [α/Fe] abundances ranging from −0.20 to 0.60 dex at MILES resolution (FWHM=2.5 Å) and wavelength coverage (3540.5 − 7409.6 Å). We make the sMILES library publicly available.

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Abundance ratios in dwarf elliptical galaxies

Cited by 9 publications

References 109 publications

The chemical composition of globular clusters in the Local Group

The chemical composition of globular clusters in the Local Group

Detection of young (≤20 Myr) stellar populations in apparently quenched low-mass galaxies using red spectral line indices

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

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