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GJ 436b: Polar Orbit May Flag Unseen Companion

18 Dec 2017, 16:01 UTC
GJ 436b: Polar Orbit May Flag Unseen Companion
(200 words excerpt, click title or image to see full post)

Any thought that our Solar System offers a template for other stellar systems has pretty much vanished in the panoply of system architectures now exposed to our observation. But it seemed rational, in the days before we knew of the existence of other systems, to imagine that if they were there, they would be more or less well ordered. Planets presumably orbited in the equatorial plane of their star, all more or less co-planar (and if Pluto didn’t quite fit the bill, that was just more evidence of the features that would one day cause it to become a ‘dwarf planet’).
But looking at the eight planets that remained after Pluto’s ‘demotion,’ we see planets that are co-planar within about 7 degrees of difference. And as Ethan Siegel (Lewis & Clark College) points out, if we take Mercury out of the mix, the deviation from the plane is only about two degrees (Mercury’s inclination is 7 degrees). Likewise, planets in our system line up well with the Sun’s rotation axis. But some systems deviate far from this expected scenario.
This morning in Nature we learn more about the GJ 436 system, a red dwarf already in the public eye ...

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