Given the large amount of science news published online and in print each day, it's always nice to find follow-ups on the relatively obscure topics posted here.
And so I smiled earlier today when I saw on ScienceDaily an article about the latest research on CoRoT-7b, the fast-orbiting exoplanet some 500 light years away that was mentioned in my last post. Readers may recall that astronomers recently determined that CoRoT-7b is just slightly less than twice the diameter of Earth, about five times Earth's mass, and similar in structure.
Structure--meaning rocky--is the key, because other similarities with Earth today are practically non-existent.
Apart from orbiting its star so rapidly (once every 3 days, 17 hours), CoRoT-7b is only about 1.6 million miles away from it -- 23 times less than the distance from our Sun to Mercury. And if this isn't distinctive enough, one side of the planet always faces its star while the other is in shadow, which means the exposed surface is extremely hot. Just how hot is it? The estimated surface temperature--literally the source of yesterday's news--is about 4,220 degrees Fahrenheit.
Because of the extremely high surface temperature, "The only atmosphere this object has is produced from vapor arising from hot molten silicates in a lava lake or lava ocean," according to Bruce Fegley of Washington University's Department of Earth and Planetary Sciences, who modeled CoRoT-7b's atmosphere with Laura Schaefer of WU's Planetary Chemistry Laboratory.
Lakes or possibly oceans of molten lava are interesting enough to think about, but all the vapor from those molten silicates apparently makes things even stranger.
Reporting the features of their silicate atmosphere model in the October 1 issue of The Astrophysical Journal, Fegley and Schaefer suggest that CoRoT-7b's atmosphere is mostly composed of sodium, postassium, silicon monoxide, and--big surprise to people like me--oxygen, which comes from all that vaporized surface rock. ScienceDaily quotes Fegley on the implications of the chemistry:
"As you go higher the atmosphere gets cooler and eventually you get saturated with different types of 'rock' the way you get saturated with water in the atmosphere of Earth. But instead of a water cloud forming and then raining water droplets, you get a 'rock cloud' forming and it starts raining out little pebbles of different types of rock."
Verfiable or not, the fact that planetary scientists can make this kind of inference based data collected from so far away is nothing short of astonishing.
Next stop: Carl Edward Sagan
Banner bus photo credit: Dorothy Delina Porter