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The exoplanets discovered so far have been mostly around relatively nearby and bright stars. As a result, the host stars are mostly (i) in the Galactic disk, (ii) relatively massive, and (iii) relatively metal rich. The aim of the SWEEPS project is to extend our knowledge to stars which (i) are in a different part of the Galaxy, (ii) have lower masses, and (iii) have a large range of metallicities. To achieve this goal, we used the Hubble Space Telescope to search for transiting planets around F, G, K, and M dwarfs in the Galactic bulge. We photometrically monitored 180,000 stars in a dense bulge field continuously for 7 days. We discovered 16 candidate transiting extrasolar planets with periods of 0.6 to 4.2 days, including a new class of ultra-short period planets (USPPs) with P < 1.2 days. Radial-velocity observations of the two brightest candidates support their planetary nature. These results suggest that planets are as abundant in the Galactic bulge as they are in the solar neighborhood, and they are equally abundant around low-mass stars (within a factor 2). The planet frequency increases with metallicity even for the stars in the Galactic bulge. All the USPP hosts are low-mass stars, suggesting either that close-in planets around higher-mass stars are irradiatively evaporated, or that the planets can migrate to close-in orbits only around such old and low-mass stars.
We summarize the contribution of the HATNet project to extrasolar planet science, highlighting published planets (HAT-P-1b through HAT-P-26b). We also briefly discuss the operations, data analysis, candidate selection and confirmation procedures, and
Our understanding of the chemical evolution of the Galactic bulge requires the determination of abundances in large samples of giant stars and planetary nebulae (PNe). We discuss PNe abundances in the Galactic bulge and compare these results with tho
We present the microlensing optical depth towards the Galactic bulge based on the detection of 99 events found in our Difference Image Analysis (DIA) survey. This analysis encompasses three years of data, covering ~ 17 million stars in ~ 4 deg^2, to
We report the detection of 45 candidate microlensing events in fields toward the Galactic bulge. These come from the analysis of 24 fields containing 12.6 million stars observed for 190 days in 1993. Many of these events are of extremely high signal
The detection of Earth-like planets, exocomets or Kuiper belts show that the different components found in the solar system should also be present in other planetary systems. Trojans are one of these components and can be considered fossils of the fi