The planet orbits in fact very close to its star, so much so that its year is the shortest ever measured: it lasts just 19 hours. “WASP43-b is a planet the size of Jupiter but twice as massive,” says Isabella Pagano, INAF – Catania Astrophysical Observatory and an expert in the research and study of exoplanets.
It reveals the most accurate map of the atmosphere of a planet outside the Solar System. It was obtained, and published in the journal Science, by the research team led by Kevin B. Stevenson, of the Department of Astronomy and Astrophysics at the University of Chicago. The team got a map so complete because the researchers were able to observe three-year history of the planet, but to do so it took just four days.
WASP-43b is a transiting planet in orbit around the young, active, and low-mass star WASP-43 in the constellation Sextans. The planet is a Hot Jupiter with a mass twice that of Jupiter, and a radius equal to Jupiter’s. WASP-43b was flagged as a candidate by the SuperWASP program before they conducted follow-ups using instruments at La Silla Observatory in Chile, which confirmed the planet’s existence and provided orbital and physical characteristics. The planet’s discovery was published on April 14, 2011.
The planet orbits in fact very close to its star, so much so that its year is the shortest ever measured: it lasts just 19 hours. Called Wasp-43b, is a giant planet and has a mass twice that of Jupiter. To observe the atmosphere with unprecedented detail, the Space Telescope NASA / ESA Hubble was on charge.
“WASP43-b is a planet the size of Jupiter but twice as massive – explains Isabella Pagano, INAF – Catania Astrophysical Observatory and an expert in the research and study of exoplanets – that orbit around a star a bit cooler than the Sun, always showing the same face to the star as in the Earth-Moon system.”
“Because of the proximity to the star (WASP-43b is 40 times closer to the star than Mercury is to the Sun) – continues the researcher – its atmosphere is extremely radiated more than is that of the gas planets in the solar system. With the WFC3 on board the Hubble Space Telescope has been possible to obtain a map of the temperature of the atmosphere of WASP-43b at different heights, uncovering in this way that this slowly decreases with the height and that there is a significant temperature difference between the illuminated hemisphere, where it is always day, and the darkness, where it is always night, at any altitude. This result tells us that in this atmosphere are not in operation efficient mechanisms for remixing. The measures also highlight the presence of water vapor in the atmosphere of WASP-43b “.
“It is the first time – said Isabella Pagano – we can reconstruct the distribution of temperature with height in this detail. Similar observations will be possible also for other types of extrasolar planets with the James Webb Space Telescope (JWST), the space telescope 6.5m being developed by NASA, ESA and CSA (Canadian Space Agency), which will be launched in 2018 “.