Spectroscopy of globular clusters in the dwarf spheroidal galaxy IKN

TL;DR

This study analyzes the properties of four globular clusters in the dwarf galaxy IKN using moderate resolution spectra to determine their velocities, ages, metallicities, and elemental abundances, providing new insights into their characteristics.

Contribution

First spectroscopic analysis of IKN's globular clusters, estimating their velocities, ages, metallicities, and elemental abundances, with implications for galaxy formation.

Findings

IKN4 and IKN5 are approximately 12.6 Gyr old with low metallicity.

All clusters show signs of blue horizontal branches.

Clusters IKN1 and IKN3 likely share similar ages and metallicities with IKN4 and IKN5.

Abstract

Moderate resolution spectra of four globular clusters in the dwarf spheroidal galaxy IKN obtained with the 6-m telescope of the Special Astrophysical Observatory have been used to determine the radial velocities, ages, and metallicities of the clusters, and also to derive the first approximate estimates of the abundances of Mg, Ca, and C. Cross-correlation with radial-velocity standards, fitting of the observed spectra with model spectra, diagnostic diagrams based on the Lick absorption indices, and comparison of the spectra and absorption indices with those of Galactic globular clusters are applied. The integrated-light (IL) spectrum of the two bright clusters IKN4 and IKN5, which are close to the center of the galaxy in projection on the celestial sphere, yields the heliocentric radial velocity $V_h= 38\pm30$ km/s, age $T=12.6\pm2$ Gyr, metallicity $[Fe/H]=-2.1\pm0.2$ dex and abundance of $\alpha$-process elements $[\alpha/Fe] \sim 0.5$ dex. The IL spectrum of the two weaker clusters IKN1 and IKN3, which are far from the center of the galaxy, yields the radial velocity $V_h=-39 \pm 50$ km/s. Despite of the low signal to noise ratio in the summary spectrum of IKN1 and IKN3, one can conclude from the comparison of the results of different used methods, that IKN1 and IKN3 have seemingly the same age and metallicity as IKN4 and IKN5. According to the measured Lick indices H$_{\delta_{\rm F}}$ and H$_{\beta}$, the studied globular clusters in IKN have blue horizontal branches.