UCL Press Release: When do gas giants reach the point of no return?
6 December 2007
Planetary scientists at UCL have identified the point at which a star causes the atmosphere of an orbiting gas giant to become critically unstable, as reported in this week's Nature (December 6).
Depending upon their proximity to a host star, giant Jupiter-like planets have atmospheres which are either stable and thin, or unstable and rapidly expanding. This new research enables us to work out whether planets in other systems are stable or unstable by using a three dimensional model to characterise their upper atmospheres.
Tommi Koskinen of UCL Physics & Astronomy is lead author of the paper and says: "We know that Jupiter has a thin, stable atmosphere and orbits the Sun at five Astronomical Units (AU) - or five times the distance between the Sun and the Earth. In contrast, we also know that closely orbiting exoplanets like HD209458b - which orbits about 100 times closer to its sun than Jupiter does - has a very expanded atmosphere which is boiling off into space. Our team wanted to find out at what point this change takes place, and how it happens."
To read the full press release, use the link at the top of this article.