Dynamics of Multiple Stellar Populations in Old Globular clusters

Dynamics of Multiple Stellar Populations in Old Globular clusters

Old Galactic Globular clusters (GCs) were once considered simple objects, composed of a simple stellar population, where all stars share the same age, chemistry and metallicity. In the last decades, the exquisite photometry provided by the Hubble Space Telescope revealed the presence of Multiple Stellar populations with different light-element abundance in nearly all GCs. Their origin is one of the greatest mysteries of modern astrophysics. The internal dynamics of multiple stellar populations in globular clusters (GCs) provides unique constraints on the physical processes responsible for their formation. Specifically, the present-day kinematics of cluster stars, such as rotation and velocity dispersion, could be related to the initial configuration of the system. In recent work, we provided the first study of the kinematics of different stellar populations in NGC 0104 over a large field of view in the plane of the sky, exploiting Gaia Data Release 2 (DR2) proper motions combined with multi-band ground-based photometry. In my Ph.D., I combine Gaia DR2 proper motions and Very Large Telescope radial velocities with space- and ground-based photometry to investigate the kinematics along the line of sight and in the plane of the sky of multiple populations in seven type-I GCs, namely NGC 0104, NGC 0288, NGC 5904, NGC 6121, NGC 6254, NGC 6752, and NGC 6838 and 2 type-II GCs, NGC 5139 (Omega Centauri) and NGC 6656 (M 22). The analysis shows evidences of a different internal dynamics of at least 3 globular clusters. Furthermore, the analysis of stellar populations with different light- and heavy-element abundances reveals interensting results.

More info : Cordoni et al. (2020)a and Cordoni et al. (2020b)

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Giacomo Cordoni
Astronomy Ph.D. student

Publications

Talks

Internal Dynamics of Multiple Stellar Populations in Galactic Globular clusters

Dynamics of Multiple Stellar Populations in type-II Globular clusters with Gaia and HST

Dynamics of Multiple Stellar Populations in Globular clusters with Gaia