Sagittarius Window Eclipsing Extrasolar Planet Search

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The Sagittarius Window Eclipsing Extrasolar Planet Search, or SWEEPS, was an astronomical survey. It was carried out in 2006. SWEEPS used the Hubble Space Telescope to look at 180,000 stars for seven days to find extrasolar planets.[1]

Area looked at[change | change source]

SWEEPS search area.
SWEEPS search area detail.

The stars that SWEEPS monitored were all in the Sagittarius-I Window. This is a rare transparent look at the huge group of closely packed stars at the Milky Way's centre (central bulge), in the Sagittarius constellation. Our view to most of the stars in the centre of the galaxy is blocked by lanes of dust. These stars are about 27,000 light years from Earth.[2]


Planets discovered[change | change source]

Sixteen planets were discovered by SWEEPS. They took from 0.6 to 4.2 days to go around the Sun. Planets which took less than 1.2 days to go around the sun have not been detected yet; these have been called "ultra-short period planets" (USPPs) by the search team. USPPs were discovered only around stars with a low mass. This means that larger stars might have destroyed any planets orbiting so closely, or that planets could not move as far inward around larger stars.[3]

SWEEPS-4 and SWEEPS-11 orbited stars that were very different to other stars close by. This made it possible for these to be looked at again using the radial velocity method. Their masses could then be found.[2]

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