NASA's Kepler Discovers Multiple Planets Orbiting a Pair of Stars 121
DevotedSkeptic writes "Kepler has continued its stellar (pun intended) discovery spree, this time locating multiple planets orbiting a binary star system. This is especially interesting because it proves that more than one planet can form under the stresses of a binary star system. The system is known as a circumbinary planetary system, a mechanism where a planet orbits two stars. Prior to this discovery, having multiple planets in a circumbinary system was unproven. Named Kepler-47, the system consists of a pair of orbiting stars that eclipse each other every 7.5 days. One star is similar in size to our Sol, however it only provides approximately 84% of Sol's light, the other is smaller, measuring one third of the size of Sol and emits less than 1% of Sol's light. Kepler-47b is the closer planet to its two suns, orbiting in 50 Earth days. Kepler-47c is further out and orbits every 303 days, within the Goldilocks zone. 'Unlike our sun, many stars are part of multiple-star systems where two or more stars orbit one another. The question always has been — do they have planets and planetary systems? This Kepler discovery proves that they do,' said William Borucki, Kepler mission principal investigator at NASA's Ames Research Center in Moffett Field, Calif. 'In our search for habitable planets, we have found more opportunities for life to exist.'"
Re:well ... (Score:5, Interesting)
You win for now...nerd
That's a compliment. Of course, even the mainstream news sites are saying this is "like Tatooine". Of course it isn't Tatooine itself, since Tatooine is long ago in a galaxy far, far away. This is in our own galaxy only 5000 light years away; the Mayans and Egyptians were still building pyramids when the light we're measuring left those stars.
What's exciting about this isn't that it's like Tatooine (or a lot of other science fiction star systems) but that it exists at all. It was formerly thought impossible for a binary star system to have planets. TFA I read earlier this morning said one of them was the size of Neptune and in the goldilocks zone, and wondered if the Neptune-sized planet had moons, and how strange it would be to be standing on one of those moons.
It seems likely that the outer, Neptune sized planet would have moons, since all the gas giants in our system do. Imagine, two suns, a HUGE GIANT moon (the planet) taking half the sky, and other moons visible as well.
Too bad it's impossible to get 5k light years away, I'd love to see the place.
Re:Liquid water? (Score:5, Interesting)
There are those who think that tidal forces are part of the reason complex and even intelligent life arose on Earth, and that without our highly-unlikely over-sized moon, we wouldn't be here to talk about it. We have temperature variations on the order of 20% (absolute) and call it "seasonal".
With that thought in mind, I've wondered if looking for a small rocky planet in the Goldilocks zone is the best way to look for life. I've wondered if a small rocky moon orbiting a gas giant might be a more likely place to find complex life. On the other hand it was disappointing to hear that there would never be colonies on Ganymede because of radiation near Jupiter, though I know nothing of the intensity, or whether a planetary magnetic field and atmosphere would shield it, etc.
Re:well ... (Score:2, Interesting)
You win for now...nerd
Too bad it's impossible to get 5k light years away, I'd love to see the place.
Always remember that The Royal Astronomical Society definitively proved that it was impossible for a passenger train to travel >= 32 mph lest all the oxygen would be sucked out of the rail car. It has to be true since it was proved with science!
Once the branch of mathematics is discovered that will solve such limits problems as division by zero and the speed of light; we could very well make that trip in a matter of minutes.
Yet another reason that we need to support pure basic fundamental research. (repetition was intentional)
Re:well ... (Score:4, Interesting)
I know they said that the planets formed around the system, but I was wondering if they could also have been later captures of planets expelled from other systems by gravitational interaction. In other words, planets can certainly orbit multi-star systems, but they may still be unable to form under those conditions. My reading of the article doesn't seem to exclude that as a possibility although they appear to be very clear on the fact they think the planets were formed in that system.
Of course, you'd have to presume that it is possible for multiple objects to form in a system that is already multi-stellar, but the idea was never that they couldn't form, but that extreme gravitational conditions would eject extra matter as soon as the stellar objects formed, leaving only the most massive objects to be stable over long periods of time.
Re:well ... (Score:2, Interesting)
It was formerly thought impossible for a binary star system to have planets.
It wasn't thought that to be impossible for binary systems to have planets, only thought that it is impossible for some situations. Orbits can quickly become unstable when you have a planet trying to navigate its way closely around two stars. However, orbits are just fine if the two stars are much closer together than the planet's orbit in which case the two stars almost act like a single central body (e.g. like this discovery), or if one of the stars is very far away, at which point the second start is like a distant gas giant or another planet around the system.
More recent work has asked questions of what binary systems due to a protoplanetary disk, and if it could prevent planet formation. Sometimes configurations do make planets much harder to form, but others were found to make it easier.