English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present a spectroscopic analysis of the metallicities, ages, andalpha-elements of the globular clusters (GCs) in the giant elliptical galaxy(gE) NGC 4636 in the Virgo cluster. Line indices of the GCs are measured fromthe integrated spectra obtained with Faint Object Camera and Spectrograph(FOCAS) on the Subaru 8.2 m telescope. We derive [Fe/H] values of 59 GCs basedon the Brodie & Huchra method, and [Z/H], age, and [a/Fe] values of 33 GCs fromthe comparison of the Lick line indices with single stellar population models.The metallicity distribution of NGC 4636 GCs shows a hint of a bimodality withtwo peaks at [Fe/H]=-1.23 (sigma=0.32) and -0.35 (sigma=0.19). The age spreadis large from 2 Gyr to 15 Gyr and the fraction of young GCs with age < 5 Gyr isabout 27%. The [a/Fe] of the GCs shows a broad distribution with a mean value[a/Fe]~0.14 dex. The dependence of these chemical properties on thegalactocentric radius is weak. We also derive the metallicities, ages, and[a/Fe] values for the GCs in other nearby gEs (M87, M49, M60, NGC 5128, NGC1399, and NGC 1407) from the line index data in the literature using the samemethods as used for NGC 4636 GCs. The metallicity distribution of GCs in thecombined sample of seven gEs including NGC 4636 is found to be bimodal,supported by the KMM test with a significance level of >99.9%. All these gEsharbor some young GCs with ages less than 5 Gyr. The mean age of the metal-richGCs ([Fe/H] > -0.9) is about 3 Gyr younger than that of the metal-poor GCs. Themean value of [a/Fe] of the gE GCs is smaller than that of the Milky Way GCs.We discuss these results in the context of GC formation in gEs.

The Globular Cluster System of NGC 4636 and Formation of Globular Clusters in Giant Elliptical Galaxies