What, yet another Tatooine? Two of'em in one system to boot? Yep, and it's getting fair pickup in media. Mostly with mention of that Star Wars and George Lucas bit of prescience. Reporters seem to have gotten that angle by themselves. At least, the two press releases down below in Grist don't mentiong Tatooine. Media almost all have a few basics such as how far away this system, Kepler-47 is, how large the planets are, and some necessary verbiage on whether one of both might harbor life. The answer to that latter one is yes just barely perhaps. One of these worlds is in an orbit lasting just under one Earth year, going around a double system that in total is about as bright and sunny as our own home star. Ergo, one can imagine liquid water there. It's the Goldilocks zone, to apply another popular metaphor. While the planet is the size of Neptune, so itself is likely sterile, perhaps it has a large moon that could be an evolution incubator (making it, for another fiction simile, sort of like Avatar's planet Pandora).
A giant team of authors reported it at a meeting of the International Astronomical Union in Beijing at the convention center in the city's four-year-old Olympic Park. A paper on it in this week's Science came off embargo two days early to coincide with the presentation there.
The breaking news that is in media so far does not get much into the extensive detective work that extracted the existence of both planets and both stars from eclipse (or transit) light curves as the four objects crossed one another's paths as seen from here. Also, not much on the additional observations from the ground to measures doppler shifts and get the system members' absolute velocities, masses, and orbital sizes. That they are all in the same plane and presumably with the same rotation sense might raise or answer questions about planetary and double star formations. Does this help explain whether the kind of protostellar cloud collapse that makes single-star systems is necessary different from those that make double star systems, or systems that include the 'failed star' brown dwarfs that fully fit neither star nor planet classification. Ignorant minds (mine) want to know. One thing does make several accounts: If multiple star systems can spawn planets with some regularity, that greatly increases the number of planets that can be expected to exist in our galaxy.
And few news stories salute the astronomers for coping with the irregularity of the timing of such passages – two stars doing a dance make for a moving target, so to speak, as the outlying planets go around – and figuring out what's going on. But, this is daily news. Plenty here for anybody who wants to dig a feature up. Start writing about accretion disk dynamics for the daily wire an editor might just shout 'cut it OUT!' Perhaps some among the authors have blogs, and have made the adventure public that way.
Further, to get deep into the thickets of my own perplexity, the naming system is sort of cockamamie. We have Kepler-47A, the big star, and Kepler-47B, the little star, near as I can tell. Then there are the planets, Kepler-47b and -47c. One cannot have a planet 47a because 'a' whether capitalized or not is reserved for a star? Yikes. Why not have just one set of letters from most massive to least, or first discovered to last, without using capitalization to distinguish star from planet? What if a brown dwarf were among them? Would it be capitalized or not? No doubt, at this IAU meeting, a whole committee is devoted to just such matters and may be convened as I write. If it weren't near midnight there.
Stories:
- Space.com – Charles Q. Choi: Two alien Planets Found with Twin suns Like 'Star Wars' Tatooine ;
- Space.com – Karl Tate: How 'Tatooine' Planets Orbit Twin Stars of Kepler-47 (infographic).
- Los Angeles Times – Thomas H. Maugh II: In a first, astronomers see two planets orbiting binary stars ; Here's a welcome switch. Maugh uses Tatooine but mainly and literally to illuminate the differences between this system and that imagined for Luke Skywalker's world.
- Discover Magazine blogs/ Bad Astronomy – Phil Plait: Kepler finds a planet in a binary's star's habitable zone ; Plait, being an astronomer and boss of one of the most popular science blogs on planet Sol-d, packs it with info and background. But doesn't address any of my questions about nomenclature and accretion/collapse disks. They might be too dumb.
- Sky & Telescope – Monica Young: A Tatooine Family ; A lot in this one on competing dynamic hypotheses to fit to the new data.
- National Geographic – Luna Shyr: Double Planets Found Orbiting Twin Stars ; Filed from Beijing.
- Forbes – Alex Knapp: NASA finds Multiple Planets Circling Binary Star System ; Hey, and yippee. Without much followup detail, but it's here. One astronomer tells him that this well-organized system is hard to explain "using the currently accepted paradigm" of planetary formation. But there is not much reporting initiative behind that. The quote is lifted from the NASA press release (see Grist below).
- Wired – Duncan Geere: Astronomers find Double-Planet, Double-Star System ;
- Science News – Nadia Drake (another filed from the meeting): Exoplanet pair orbits two stars ;
- BloombergBusinessweek – Elizabeth Lopatto: Two-Star Dual Planet System Found 5000 Light-Years Away ;
- Cosmos (Australia) Rachael Bayliss: New duo of Kepler planets orbit two suns ; Hmm, in Australia does the grammar use the rules of agreement that the Brits apply, with collective nounts serving as plural? Never mind – the story does suggest that theorists are going to have some work to do explaining the formation process of such systems and putting it into a larger theoretical and genealogical framework.
- BBC – "Tatooine-like" double-star systems can host planets ; Why is Tatooine-like in quotation marks? Perhaps that it is fiction. But the story quotes nobody as using the term.
Grist for the Mill: San Diego State University Press Release; NASA-Kepler Mission Press Release ;
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