相关论文: Multiple Stellar Populations in NGC 2808: a Case S…

Globular clusters (GCs) are among the oldest stellar systems in the universe. As such, GCs population are valuable fossil tracers of galaxy formation and interaction history. We use the multi-band wide-field images obtained with the VST to…

We use Hubble Space Telescope (HST) imaging from the ACS Treasury Survey to determine fits for single population isochrones of 69 Galactic globular clusters. Using robust Bayesian analysis techniques, we simultaneously determine ages,…

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 use a matched filter algorithm to find and study clusters in both N-body simulations artificially populated with galaxies and the 2MASS survey. In addition to numerous checks of the matched filter algorithm, we present results on the…

We present Hubble Space Telescope (HST) photometric results for NGC 6402, a highly reddened very luminous Galactic globular cluster (GC). Recent spectroscopic observations of its red giant stars have shown a quite peculiar behavior in the…

(abridged) This thesis presents theoretical and statistical techniques broadly related to systems of dynamically-interacting particles composed of several different types of populations. They are applied to observations of dense star…

Spreads in light element abundances among stars (a.k.a. multiple populations) are observed in nearly all globular clusters. One way to map such chemical variations using high-precision photometry is to employ a suitable combination of…

The central regions of six Galactic Globular Clusters (GGCs) (M3, M80, M10, M13, M92 and NGC 288) have been imaged using HST-WFPC2 and the ultraviolet (UV) filters (F255W, F336W). The selected sample covers a large range in both central…

We present Ca-CN-CH-NH photometry for the well-known globular cluster (GC) M3 (NGC 5272). We show new evidence for two M3 populations with distinctly different carbon and nitrogen abundances, seen in a sharp division between CN-weak and…

We present the first evidence of multiple populations in the Galactic globular cluster NGC 6362. We used optical and near-UV Hubble Space Telescope and ground based photometry, finding that both the sub giant and red giant branches are…

Galaxy clusters are powerful probes of astrophysics and cosmology through gravitational lensing: the clusters' mass, dominated by 85% dark matter, distorts background light. Yet, mass reconstruction lacks the scalability and large-scale…

Optimised population synthesis provides an empirical method to extract the relative mix of stellar evolutionary stages and the distribution of atmospheric parameters within unresolved stellar systems, yet a robust validation of this method…

In the last years, photometric and spectroscopic evidence has demonstrated that many, maybe all the Globular Clusters (GC) host multiple stellar populations. High-resolution spectroscopy has established that, while most GCs are…

Star clusters are ideal tracers of star formation activity in systems outside the volume that can be studied using individual, resolved stars. These unresolved clusters span orders of magnitude in brightness and mass, and their formation is…

The Galactic globular cluster NGC 1851 has raised much interest since HST photometry revealed that it hosts a double subgiant branch. Here we report on our homogeneous study into the cyanogen (CN) bandstrengths in the RGB population (17…

Globular Clusters (GCs) exhibit star-to-star variations in specific elements (e.g., He, C, N, O, Na, Al) that bare the hallmark of high temperature H burning. These abundance variations can be observed spectroscopically and also…

Globular clusters (GCs) are fundamental for understanding the integrated light of old stellar populations and galaxy assembly processes. However, the role of hot, evolved stars, such as horizontal branch (HB), extreme HB, and blue…

Using Magellan/IMACS images covering a 1.2 x 1.2 sq. degree FOV with seeing of 0.4"-0.6", we have applied convolution techniques to analyse the light distribution of 364 confirmed globular cluster in the field of NGC 5128 and to obtain…

Multiple stellar populations in globular clusters (GCs) are distinct by their different abundances of light elements. The abundance anti-correlations point towards a nucleosynthesis origin due to high-temperature H burning, but it remains…

In this paper, we show that preprocessing data using a variant of rank transformation called 'Average Rank over an Ensemble of Sub-samples (ARES)' makes clustering algorithms robust to data representation and enable them to detect varying…