I had been wanting to write about Kepler since Kepler-22b was announced in early December. There was no rhyme or reason to why my post came out this morning, I just had time to write it, so I did. Not 12 hours after my post anticipating an awesome year of discovery, I heard about two new announcements based on Kepler data and another amazing exoplanet discovery unrelated to Kepler. I must be a prophet.
Truthfully, this was not an act of fate on the part of the universe. Rather, I wasn’t paying attention and didn’t realize that the AAS (American Astronomical Society) is meeting in Austin, Texas this week, so we can expect a more than usual number of announcements this week.
Anyway, first the Kepler goodies.
The confirmation of planets Kepler-34b and Kepler-35b were announced today via a published article in Nature (abstract). These planets are both “circum-binary” meaning they each orbit a pair of stars (like in my blog banner!). These are the second and third such systems after Kepler-16b that was only announced last September. With more than a single data point available, they were able to do a statistical analysis and have concluded that there are probably several million of these types of systems in our galaxy. In other words, 1% of all binary star systems have circum-binary planets.
These two new planets are awesome but they are not Earth-sized, so are of a bit less interest than the second announcement today.
So what’s the big deal? Well let me introduce to you KOI-961, which is a planetary system with 3 planets confirmed by Kepler, all of them the smallest exoplanets ever discovered. Yes, you read that right. Rather than explain it to you more, just check out this graphic.
Mind blown yet? Mine pretty nearly is. Unfortunately, KOI-961 is a red dwarf, not a sun-like star, and none of these planets are in the habitable zone. In either case, this demonstrates that we have the technology to detect planets of Mars size and larger. Realize that we had no confirmed Earth-sized planets only a year ago. Actually, just over a month ago we had no confirmed Earth-sized planets. Wow! At this point, it’s only a matter of statistics until we find the first small rocky planet that is also in the habitable zone, that is also around a sun-like star, and that is also close enough to us that our forseeable descendants could travel there. Which brings us to the last awesome exoplanet announcement of the day.
An independent team called PLANET is using the technique of microlensing to detect exoplanets. The unique thing about this technique is that it does not depend upon the fact that the orbital planes of the planets are oriented “just so” like the transit technique that Kepler uses. It is also less biased towards larger planets. Therefore, when they saw 3 out of 40 of the lensing events they sampled showing signs of having planets, they were able to do a statistical analysis and conclude that there is probably at least one planet for every star in the Milky Way – 100 billion. Or as Carl Sagan would say, billions and billions…
Honestly, the statistics that led them to this conclusion is beyond me. Go read about it here, here and here for yourself (the last link from earthsky.org is the best). The point is, repeated different types of statistical analyses over the past few years continue to indicate that planets are everywhere.
Stop me if you’ve heard this before, but this is going to be a good year for exoplanet science.