This is an image from the NASA/ESA Hubble Space Telescope showing a vast, complex dust structure, about 240 billion kilometres across, enveloping the young star HR 4796A. A bright, narrow inner ring of dust is already known to encircle the star and may have been corralled by the gravitational pull of an unseen giant planet. This newly discovered huge dust structure around the system may have implications for what this yet-unseen planetary system looks like around the 8-million-year-old star, which is in its formative years of planet construction. The debris field of very fine dust was likely created from collisions among developing infant planets near the star, evidenced by a bright ring of dusty debris seen 11 billion kilometres from the star. The pressure of starlight from the star, which is 23 times more luminous than the Sun, then expelled the dust far into space.

Link:

• NASA press release

This image shows an artist’s impression of the ten hot Jupiter exoplanets studied by David Sing and his colleagues.

The images are to scale with each other. HAT-P-12b, the smallest of them, is approximately the size of Jupiter, while WASP-17b, the largest planet in the sample, is almost twice the size. The planets are also depicted with a variety of different cloud properties.

There is almost no information about the colours of the planets available, with the exception of HD 189733b, which became known as the blue planet (heic1312).

The hottest planets within the sample are portrayed with a glowing night side. This effect is strongest on WASP-12b, the hottest exoplanet in the sample, but also visible on WASP-19b and WASP-17b. It is also known that several of the planets exhibit strong Rayleigh scattering. This effect causes the blue hue of the daytime sky and the reddening of the Sun at sunset on Earth. It is also visible as a blue edge on the planets WASP-6b, HD 189733b, HAT-P-12b, and HD 209458b.

The wind patterns shown on these ten planets, which resemble the visible structures on Jupiter, are based on theoretical models

This is an artist's impression of the Jupiter-size extrasolar planet, HD 189733b, being eclipsed by its parent star. Astronomers using the Hubble Space Telescope have measured carbon dioxide and carbon monoxide in the planet's atmosphere. The planet is a 'hot Jupiter,' which is so close to its parent star that it completes an orbit in only 2.2 days.

This type of observation is best done when the planet's orbit carries it behind the star (as seen from Earth), which allows an opportunity to subtract the light of the star alone (when the planet is blocked) from that of the star and planet together prior to eclipse. This allows astronomers to isolate the infrared emission of the planet and make spectroscopic observations that chemically analyse the day side atmosphere.

The planet is too hot for life, as we know it. But under the right conditions, on a more Earth-like world, carbon dioxide can indicate the presence of extraterrestrial life. This observation demonstrates that chemical biotracers can be detected by space telescope observations.