Constraints on the Formation of the Globular Cluster IC 4499 from Multi-Wavelength Photometry

TL;DR

This study provides detailed multiband photometry of the globular cluster IC 4499, determining its age, reddening, and structural properties, and finds it to be coeval with other Galactic clusters and likely a single stellar population.

Contribution

It offers new multiband photometric data and analysis of IC 4499, clarifying its age, structure, and stellar population characteristics, challenging previous suggestions of a younger age.

Findings

IC 4499 has an age of 12 ± 1 Gyr.

The cluster's density profile does not flatten out to at least 800 arcsec.

No anomalous UV color spreads detected among red giant branch stars.

Abstract

We present new multiband photometry for the Galactic globular cluster IC 4499 extending well past the main sequence turn-off in the U, B, V, R, I, and DDO51 bands. This photometry is used to determine that IC4499 has an age of 12 pm 1 Gyr and a cluster reddening of E(B-V) = 0.22 pm 0.02. Hence, IC 4499 is coeval with the majority of Galactic GCs, in contrast to suggestions of a younger age. The density profile of the cluster is observed to not flatten out to at least r~800 arcsec, implying that either the tidal radius of this cluster is larger than previously estimated, or that IC 4499 is surrounded by a halo. Unlike the situation in some other, more massive, globular clusters, no anomalous color spreads in the UV are detected among the red giant branch stars. The small uncertainties in our photometry should allow the detection of such signatures apparently associated with variations of light elements within the cluster, suggesting that IC 4499 consists of a single stellar population.