| 9 | | |
| 10 | | My Life in the Bulge: A G-Dwarf Perspective |
| 11 | | |
| 12 | | The Galactic Bulge is very different than the Galactic disk: old, |
| 13 | | metal-rich, dense in stars, and gas-poor. We see analogs in the bulges |
| 14 | | of other spiral galaxies and in the stellar content of elliptical |
| 15 | | galaxies. While the nearness of the Bulge compared to these distant |
| 16 | | galaxies gives us the opportunity to study at least one bulge-like |
| 17 | | system in more detail, we are still forced to concentrate on the |
| 18 | | brightest stars in the Bulge: the evolved red giant and red clump |
| 19 | | stars and assume that they are representative of the entire |
| 20 | | population. Occasionally, however, a star in the Bulge can be |
| 21 | | gravitationally lensed by an intervening star, magnifying it by factos |
| 22 | | of hundreds to thousands. This provides a unique opportunity to |
| 23 | | observe the dwarf stars in the Bulge. We can then determine the |
| 24 | | abundances of elements unobservable or unreliable in giant stars and |
| 25 | | build a fuller understanding of the chemical evolution of such dense |
| 26 | | systems. In addition, we can compare the dwarf population with the |
| 27 | | giant population and see how representative the latter population is. |
| | 9 | Gravitational lensing analyses of galaxy clusters with HST/ACS bring us many interesting discoveries. Among these are dark matter substructures found in some merging galaxy clusters. Thanks to the unprecedented sensitivity and resolution of HST/ACS, these substructures are well resolved and possess high significance. I will present our gravitational lensing analyses of three interesting galaxy clusters showing distinct substructures, which can tell us about the dynamical history, the properties of the cluster components, and perhaps fundamental physics. |
