Astronomers Find ‘Impossible’ Planet Circling Tiny Star

by Joel Hruska

One of the ongoing puzzles in astronomy is that very few solar systems that we’ve examined to date look anything like ours. It’s common, for example, for solar systems to have so-called Hot Jupiters, planets the size of Jupiter that circle their host stars at a closer distance than Mercury circles our own Sun. Many solar systems have planets that fall in-between the size of Earth and Neptune, while we have no such worlds. In other solar systems, Super-Earths — rocky planets — are often found much closer to the Sun, while our largest and farthest planets are all gas giants.

These differences imply that our own theories of planetary formation and evolution may need tweaking to account for how our solar system appears to be odd, for lack of a better way of putting it. As if to reinforce that argument, astronomers have found a planet that appears to be much too large for the star it’s orbiting. Their work, published in Science, raises questions about how a system like this could form in the first place.

GJ 3512 b is a gas giant orbiting a tiny red dwarf, GJ 3512. The planet itself is in an eccentric, 204-day orbit around its star, but spends most of its time closer to its parent than Mercury is to Sol. GJ 3512, however, can only manage ~0.2 percent of our Sun’s solar output. But a planet…