Free Astronomy Magazine May-June 2016

PLANETOLOGY much more similar to each other than they are today: Kepler-36b had a thicker atmo- sphere corresponding to nearly 10 percent of its total mass, compared to 15-30 percent represented instead by Kepler-36c’s atmo- sphere. The evaporation induced by the stel- lar radiation has, over time, been more ef- fective on the inner planet’s atmosphere, not as much for its closer proximity to the star, but for its lower initial core mass, which the model developed by Owen and Mortom indi- cates to have been of 4.4 Earth masses, compared to the 7.3 Earth masses of Kepler-36c’s core; a difference that is also at the root of the different efficiency in accumulat- ing the early atmosphere. The case of Kepler-36 sys- tem will help researchers define a relationship be- tween the mass of the atmosphere and that of the core at the birth of the planets, and to better define the evolu- tionary processes affect- ing them. ROGUE PLANET IN THE BETA PICTORIS MOVING GROUP As we have just seen, that of Kepler-36 is one of those planetary systems best suited to be investigated through the transit technique, which at the same time reveals the planetary diameters, the orbital periods and even the masses if two planets orbit suf- ficiently close to each other to cause the transits of the other to be early or late, due A n exaggerat- ed depiction of the transit of the Kepler-36 planets observed from Kepler. In reality the tele- scope sees the star as a dot and does not direct- ly see the two planets. [NASA Ames, W.Stenzel] B elow, a possi- ble look of the giant rogue planet PSO J318- 22, roaming alone in space, within the Beta Pictoris moving group. [NASA]