Radiation-Blasted Exoplanets

Figure 1: Artist’s impression of CoRoT-2b - a hot-Jupiter being blasted by intense radiation from its parent star. Credit: NASA/CXC/M.Weiss.Hot-Jupiters are a class of Jupiter-sized exoplanets that orbit very close to their parent stars and receive intense amounts of stellar radiation. A typical hot-Jupiter orbits its parent star at ~1/20th the Sun-Earth distance and receives ~10,000 times more radiation that Jupiter does from the Sun. Being so close to its parent star, a hot-Jupiter is expected to be tidally-locked whereby one side continuously faces it parent star while the other side points away into the darkness of space. A study done by Daniel Fabrycky (2008) shows that reradiated thermal radiation from a hot-Jupiter carries away momentum and this can gradually change the star-planet separation distance by ~1 percent over the planet’s lifetime. For more extreme cases, this change can be as much as a few percent.Radiation is comprised of photons which carry momentum. As a result, a force is exerted on a planet when radiation is reflected, absorbed or reradiated by the planet. Radiation that is reflected or absorbed by a hot-Jupiter simply pushes it away from its parent star. However, the direction of force exerted on a hot-Jupiter by ...