Clustering clusters: unsupervised machine learning on globular cluster structural parameters

Structural Parameters of the M87 Globular Clusters

We derive structural parameters for ∼ 2000 globular clusters in the giant Virgo elliptical M87 using extremely deep Hubble Space Telescope images in F606W (V) and F814W (I) taken with the ACS/WFC. The cluster scale sizes (half-light radii rh) and ellipticities are determined from PSF-convolved Kingmodel profile fitting. We find that the rh distribution closely resembles the inner Milky Way clus...

Structural Parameters for Globular Clusters in NGC 5128. II: HST/ACS Imaging and New Clusters

We report the first results from an imaging program with the ACS camera on HST designed to measure the structural characteristics of a wide range of globular clusters in NGC 5128, the nearest giant elliptical galaxy. From 12 ACS/WFC fields, we have measured a total of 62 previously known globular clusters and have discovered 69 new high-probability cluster candidates not found in any previous

Learning About Young Globular Clusters

IV-N yes RG 715 I 90 min -19 (up to 5 hours) of selected objects through the available Ha and S I1 interference filters which have a useful field of about 2°. The approximate limiting magnitudes for direct plates are quoted in the table. They depend on the seeing; the numbers given are for medium seeing and deeper plates are obtained under excellent conditions. These values may possibly be furt...

Unsupervised Machine Learning

Globular cluster systems II : On the formation of old globular clusters and their sites of formation

We studied the metal-poor globular cluster populations of a large variety of galaxies and compared their mean metallicity with the properties of the host galaxies. For this purpose, we constructed a comprehensive database of old, metal-poor globular cluster populations, hosted by 47 galaxies spanning about 10 magnitudes in absolute brightness. The mean metallicities of the systems are found to ...