Sagittarius Window Eclipsing Extrasolar Planet Search


The Sagittarius Window Eclipsing Extrasolar Planet Search, or SWEEPS, was a 2006 astronomical survey project using the Hubble Space Telescope's Advanced Camera for Surveys - Wide Field Channel to monitor 180,000 stars for seven days to detect extrasolar planets via the transit method.

Area examined

The stars that were monitored in this astronomical survey were all located in the Sagittarius-I Window. The Sagittarius Window is a rare view to the Milky Way's central bulge stars: our view to most of the galaxy's central stars is generally blocked by lanes of dust. These stars in the galaxy's central bulge region are approximately 27,000 light years from Earth.

Planets discovered

Sixteen candidate planets were discovered with orbital periods ranging from 0.6 to 4.2 days. Planets with orbital periods less than 1.2 days have not previously been detected, and have been dubbed "ultra-short period planets" by the search team. USPPs were discovered only around low-mass stars, suggesting that larger stars destroyed any planets orbiting so closely or that planets were unable to migrate as far inward around larger stars.
Planets were found with roughly the same frequency of occurrence as in the local neighborhood of Earth.
SWEEPS-4 and SWEEPS-11 orbited stars that were sufficiently visually distinct from their neighbors that follow-up observations using the radial velocity method were possible, allowing their masses to be determined.
This table is constructed from information obtained from the Extrasolar Planets Encyclopedia and SIMBAD databases that reference the Nature article as their source.
StarConstellationRight
ascension		DeclinationApp.
mag.		Distance Spectral
type		PlanetMass
Radius
Orbital
period
Semimajor
axis
Orbital
eccentricity		Inclination
Discovery
year
Sagittarius22.2~22000?1.011.560.025?86+2006
Sagittarius25.1~22000?1.370.9120.015?86+2006
Sagittarius22.5~22000?0.871.270.021?86+2006
SWEEPS J175853.92−291120.6Sagittarius18.8~22000SWEEPS-04<3.80.814.20.055?87+2006
Sagittarius23.9~22000?1.092.3130.030?87+2006
Sagittarius19.5~22000?0.823.0390.042?86+2006
Sagittarius21.5~22000?0.91.7470.027?86+2006
Sagittarius21.7~22000?0.980.8680.017?84+2006
Sagittarius22.5~22000?1.011.6170.025?86+2006
SWEEPS J175902.00-291323.7Sagittarius26.2~22000SWEEPS-10?1.240.4240.008?84+2006
SWEEPS J175902.67−291153.5Sagittarius19.83~22000SWEEPS-119.71.131.7960.03?84+2006
Sagittarius21.8~22000?0.912.9520.038?87+2006
Sagittarius21.38~22000?0.781.6840.027?86+2006
Sagittarius22.38~22000?0.932.9650.037?87+2006
Sagittarius25.66~22000?1.370.5410.010?84+2006
Sagittarius23.78~22000?1.40.9690.017?85+2006