The 100th edition of the Carnival of Space is now up at the One-Minute Astronomer site, where I learned of the existence of Christopher Crockett’s Innumerable Worlds blog. Christopher’s story on two gas giants around subgiant stars is well worth reading. He’s a UCLA graduate student now working at Lowell Observatory who offers a good deal of background material in his posts, as in this comment on the new planets’ unusually eccentric orbits:
How planets end up on such crazy orbits is a matter that is currently being researched. These two worlds aren’t alone; many of the new worlds we’re finding sit on highly eccentric orbits. The leading hypothesis is that interactions between closely spaced planets might affect their orbits. If two planets get too close, the lighter one can get ejected from the planetary system entirely while the remaining, more massive, world is left behind on a very elliptical orbit. This is the same principle we use to slingshot probes out into deep space by stealing momentum from the planets. We may be seeing the remnants of long-past interplanetary bumper cars!
Interesting stuff, and it raises the issue of how many star-less planets might be wandering interstellar space. Not enough, according to recent studies, to explain the evident dark matter halo around the average galaxy, but enough to offer up a great deal of interesting real estate if we find that planetary ejection really is common.
Lots of good material on the latest Carnival besides this, including Brian Wang’s Projecting 250 years to a Star Trek Timeframe, which is packed with intriguing calls on population (89 billion by 2260) to the economy, with Brian’s usual set of useful links. One interesting possibility: A civilization reaching 100-200 light years in radius within 250 years. Also be sure to check astroENGINE‘s speculative piece on METI (transmitting to the stars) and Orbital Hub‘s Q&A session with alien hunter Seth Shostak, author of the recently released Confessions of an Alien Hunter.