WASHINGTON: NASA's in-space Hubble telescope has provided evidence of a new class of planets that zip round their parent stars, some completing their orbit in less than a day.
These planets are called exoplanets or extra-solar planets because they are found beyond our solar system although within the Milky Way galaxy. These 16 planets were spotted in 'the Bulge', a space that is approx. 26,000 light-years away in the center of the Milky Way and believed to be rich in stars and planets.
The discovery was made by a team of astronomers led by Baltimore-based astronomer Kailash Sahu who works for the Space Telescope Science Institute. Sahu and colleagues maintain that the 16 celestial bodies were planets and base this assertion on the 'wobble' pattern they observed.
The luminosity of the parent star dips with regularity indicating the passing of a planet. Two of these were seen to orbit very close to their stars and every time that happened, the star would be tugged by the gravitational pull of the orbiting body. From a distance the star appears to wobble as its light dips and brightens.
The presence of these objects suggests the possibility of many more planets, probably billions, scattered throughout our galaxy, an astronomer said.
The planets spotted by the Sahu-led team are each the size of our Jupiter. The parent star, though, is a lot smaller than the Sun. The astronomers call them ultra-short-period planets (USPPs) because of their very short orbits. Their orbits range between 0.4 and 3.2 days. They are also very close to their respective stars. In some cases the distance between the planet and the parent star is one eighth the distance between Mercury and the Sun. The extreme proximity might explain the 3,000ºF (1,650ºC) surface temperature the astronomers estimate the USPPs to have.
The first such extrasolar planet was spotted in 1995.
