Metal-rich stars and planet scattering

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Metal-rich stars and planet scattering

Post by Lazarus on 27th February 2013, 2:46 pm

Giant planets orbiting metal-rich stars show signatures of planet-planet interactions
http://arxiv.org/abs/1302.6244

1. Gas giants with a < 1AU orbiting metal-rich stars have a range of eccentricities, whereas those orbiting metal-poor stars are restricted to lower eccentricities.

2. Only metal-rich stars host eccentric proto-hot Jupiters undergoing tidal circularization.

3. The pile-up of short-period giant planets, missing in the Kepler sample, is a feature of metal-rich stars and is largely recovered for giants orbiting metal-rich Kepler host stars.
Suggests that smooth disk migration and scattering are both contributing to the planet population:
We expect disk migration could occur in any system, but only systems packed with giant planets which most easily form around metal-rich stars can scatter giant planets inward to large eccentricities (Trend 1), some of which tides shrink and circularize (Trend 2), creating a pile-up of short-period giants (Trend 3). Moreover, these trends support planet-planet interactions (e.g. scattering, secular chaos, or Kozai) as the dynamical migration mechanism of close-in giant planets, rather than stellar Kozai.
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Re: Metal-rich stars and planet scattering

Post by ThinkerX on 27th February 2013, 9:11 pm

Hmmm...so giant planets (and others?) orbiting 'metal poor' stars are the most likely to have stable, relatively circular orbits.

I did note in the article, though, that the authors considered anything under 43% eccentricity as 'stable'. That seems...quite a bit.

Also...years ago, I compared metallicity catalogs by different researchers which included a great many overlaps in the stars surveyed. The discrepencies were often substantial, sometimes by more than 50%. Hence, one catalogue might cite a star as having say 30% of our suns metalicity while a second would put the figure at 70%. This got even worse when the error bars were figured in. So...how good are the metalicity figures used these days?

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