Observatoire de Paris
<-   SWEEPS and the distant exoplanets  
This photograph shows part of the stellar field observed in the "SWEEPS" survey. The green circles indicate the position of 11 of the 16 host stars that have been found.
Copyright : NASA/HST, ESA, K. Sahu (STScI) and the "SWEEPS Science Team"

In 2006, another exoplanet survey was launched with the Hubble Space Telescope. This time, Hubble observed 180 000 stars close to the center of our Galaxy, i.e. at a distance of 26 000 light-years (about 8 kiloparsecs). This survey, called "SWEEPS" (for Sagittarius Window Eclipsing Extrasolar Planet Search), identified after one week of observation 16 host stars, using the method of transits.

One concludes from the observations that the exoplanets associated with the host stars are all gas giant planets with sizes comparable to Jupiter. They are in orbits with periods of only a few terrestrial days. Up to now, the available instruments are not yet sensitive enough to detect exoplanets of a smaller size at large distances from our Solar System.

The discovery of "SWEEPS" leads us to assume that there exists indeed a very large number of exoplanets in our entire Galaxy and not only in the close neighbourhood of our Solar System.