More Planet News

This week the interesting planet news continues. After last week’s massive news about Gliese 581 C, this week’s news seems pretty uneventful but it is still important in understanding the possibilities for extra solar planets. Many people may be left with a human-friendly impression of exoplanets after Gliese but the news about the temperatures on a couple of hot Jupiter planets should quickly bring those people back to the reality that most exoplanets are about as non human-friendly as is possible.

Firstly, the mapping of temperature distribution on HD 189733b shows that this planet ranges between 1200 degrees Fahrenheit on the hemisphere facing away from the star to 1900 on the hemisphere facing the star. The planet is tidally locked to its star, an inconspicuous yellow dwarf like our own star. The fact that the temperatures are not more radically different on the different sides of the planet suggest that there are some pretty ridiculous winds involved to spread the heat around, winds that scientists say could be as fast as 6,000 mi/hr. This is one of the rare times that astronomers have been able to map the full surface of an exoplanet according to temperature variations along its surface. Another interesting thing about the planet is that it goes around its star in only two Earth days and therefore is a close transiting planet. In fact, the HD 189733 system is one of our best resources for learning about close transiting planets like this.


Image of the temperature on the surface of HD 189733b courtesy of NASA

The second planet I want to talk about, HD 149026b, is even more disturbingly anti-humanity. It is one of the hottest planets ever observed with temperatures over 3700 degrees Fahrenheit! It is so hot that it is hotter than some low mass stars. This planet, unlike the other one, probably doesn’t have its heat spread around both sides. It is also pretty small for this type of planet and extremely dense with very intense gravity. Astronomers are proposing that it may be a very dark world because it is so hot. Most of the light and energy from the star is obviously being sucked up into the planet, without much being reflected off of it for us to see. All in all, this chunk of coal is one of the weirdest exoplanets discovered yet.

An artist's conception of HD149026b, the hottest planet ever seen. Courtesy of NASA.

Both discoveries were made by measuring changes in infrared radiation as these planets went behind their stars. The observations were performed with the Spitzer Space Telescope.