Terzan 5 is a stellar system located in the inner Bulge of the Galaxy and has been historically catalogued as a globular cluster. However, recent photometric (Ferraro et al. 2009) and spectroscopic (Origlia et al. 2011; Origlia et al. 2013) investigations have shown that it hosts at least three stellar populations with different iron abundances (with a total spread of Delta[Fe/H]>1 dex) thus demonstrating that Terzan 5 is not a genuine globular cluster. In addition, the striking similarity between the chemical patterns of this system and those of its surrounding environment, the Galactic Bulge, from the point of view of both the metallicity distribution and the alpha-element enrichment, suggests that Terzan 5 could be a pristine fragment of the Bulge itself.
@article{arxiv.1401.3962,
title = {Terzan 5: a pristine fragment of the Galactic Bulge?},
author = {Davide Massari and F. R. Ferraro and A. Mucciarelli and L. Origlia and E. Dalessandro and B. Lanzoni},
journal= {arXiv preprint arXiv:1401.3962},
year = {2014}
}
Comments
4 pages, 4 images, proceeding of the "Metal Production and Distribution in a Hierarchical Universe" Conference, Paris, France, October 21-25, 2013. To be published in Memorie della Societa Astronomica Italiana Supplement