ESA Science & Technology08-Jul-2005 11:29:41

Extrasolar Planets

Direct Imaging

All of the previously described methods have made direct detections by isolating the planet's light from that of the star. A direct image would be one on which the star's light is totally separated from the planet. A team of British astronomers believe that by using 8-metre telescopes, they may be able to see planets in orbit around white dwarf stars.

When the Sun dies, it will first swell into a red giant star, engulfing the planets out to Mars. It will then shed its outer layers into space and the remains will shrink into a white dwarf star. The gas giants will remain in orbit and may even spiral outwards from the star, making them easier to see. White dwarfs are dim so the contrast between a gas giant and the star falls to a factor of a thousand. That may be low enough to bring them within view of 8-metre telescopes. Observations are now being scheduled.

Eventually, to take images of the surfaces of extrasolar planets will require much larger telescopes in space, working together as interferometers.

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