Free Form: Exoplanets and Kepler-432b

Recently, a Jupiter-like exoplanet, or extrasolar planet, called Kepler-432 b was discovered with unusually high density and a mass six times larger than Jupiter's but a size that is the same as Jupiter's. In fact, Kepler-432 b is one of the most massive and densest planets we have observed. Moreover, the orbit of Kepler-432 b around a red giant (a star in a later stage of its evolution) is very small and strangely shaped for a planet so massive. The image below shows what Kepler-432 b's orbit around the red giant looks like in comparison to the orbit of Mercury around our Sun.

Orbit of Kepler-432 b Compared to Mercury
Image Credit: http://www.sciencedaily.com/releases/2015/02/150212114243.htm

Due to the shape of the orbit, which causes the planet to be closer to the star at some points of its orbit and further at others, Kepler-432 b has very extreme seasons. One year on Kepler-432 b is equivalent to 52 Earth days, and the temperatures between seasons vary from 500 degrees Celsius to 1000 degrees Celsius. Since the planet's orbit is not centered around its star, the summer season (closest to the star) is significantly shorter than the winter season (furthest from the star).

The reason this finding is interesting for astronomers is because lately, they have been finding more Jupiter-like planets orbiting older stars like red giants. Their findings have shown that the orbits of these Jupiter-like planets around red giants and other evolved stars have different characteristics than their orbits around regular, main-sequence stars. Particularly, astronomers have noted that they don't find many such planets in close orbit around giant stars. Their predictions for why this might be the case include two possibilities: either the giant stars pull the planets inward and swallow them or the Jupiter-like planets form around regular, intermediate-mass stars but don't move inward on their orbits. The finding of Kepler-432 b obviously shows that it is possible for such planets to be in close orbit around giant stars, but astronomers postulate that within the next 200 million years, the planet will be completely sucked in by the red giant.

By studying this topic, astronomers might better understand the evolution of orbiting planets as their stars evolve from main-sequence stars. This new understanding can, in turn, be used to predict what our Solar System might look like as our Sun reaches the end of its main sequence. More generally, this is one of the goals of extrasolar planetary astronomy. Through observing the characteristics of other planets and their orbital systems, we can begin to make sense our own Solar System and how it may change over time. We can also work the other way and use our Solar System to make predictions on the characteristics of other solar systems and planets. One example of this is the search for extraterrestrial life and other inhabitable planets.


Citations:
http://www.sciencedaily.com/releases/2015/02/150212114243.htm
http://www.aanda.org/articles/aa/pdf/2015/01/aa25146-14.pdf
http://www.aanda.org/articles/aa/pdf/2015/01/aa25145-14.pdf