000003407 001__ 3407
000003407 005__ 20180116111913.0
000003407 0247_ $$2DOI$$a10.1073/pnas.1604692113
000003407 037__ $$aSCART-2018-0020
000003407 100__ $$aXie, J.-W.
000003407 245__ $$aExoplanet orbital eccentricities derived from LAMOST-Kepler analysis
000003407 260__ $$c2016
000003407 520__ $$aThe nearly circular (mean eccentricity <e>~0.06) and coplanar (mean mutual inclination <i>~3 deg) orbits of the Solar System planets motivated Kant and Laplace to put forth the hypothesis that planets are formed in disks, which has developed into the widely accepted theory of planet formation. Surprisingly, the first several hundred extrasolar planets (mostly Jovian) discovered using the Radial Velocity (RV) technique are commonly on eccentric orbits (<e> ~ 0.3). This raises a fundamental question: Are the Solar System and its formation special? The Kepler mission has found thousands of transiting planets dominated by sub-Neptunes, but most of their orbital eccentricities remain unknown. By using the precise spectroscopic host star parameters from the LAMOST observations, we measure the eccentricity distributions for a large (698) and homogeneous Kepler planet sample with transit duration statistics. Nearly half of the planets are in systems with single transiting planets (singles), while the other half are multiple-transiting planets (multiples). We find an eccentricity dichotomy: on average, Kepler singles are on eccentric orbits with <e>~0.3, while the multiples are on nearly circular (<e> = 0.04^{+0.03}_{-0.04}) and coplanar (<i> = 1.4^{+0.8}_{-1.1} deg) orbits similar to the Solar System planets. Our results are consistent with previous studies of smaller samples and individual systems. We also show that Kepler multiples and solar system objects follow a common relation <e>~(1-2)x<i> between mean eccentricities and mutual inclinations. The prevalence of circular orbits and the common relation may imply that the solar system is not so atypical in the galaxy after all. 
000003407 594__ $$aNO
000003407 6531_ $$aorbital eccentricities
000003407 6531_ $$aexoplanets
000003407 6531_ $$atransit
000003407 6531_ $$asolar system
000003407 6531_ $$aplanetary dynamics
000003407 700__ $$aDong, S.
000003407 700__ $$aZhu, Z.H.
000003407 700__ $$aHuber, D.
000003407 700__ $$aZheng, Z
000003407 700__ $$aDe Cat, P.
000003407 700__ $$aFu, J.N.
000003407 700__ $$aLiu, H.-G.
000003407 700__ $$aLuo, A.
000003407 700__ $$aWu, Y.
000003407 700__ $$aZhang, H.T.
000003407 700__ $$aZhang, H.
000003407 700__ $$aZhou, J.-L.
000003407 700__ $$aCao, Z.H.
000003407 700__ $$aHou, Y.H.
000003407 700__ $$aWang, Y.F.
000003407 700__ $$aZhang, Y.
000003407 773__ $$c11431-11435$$n41$$pProceedings of the National Academy of Sciences$$v113$$y2016
000003407 8560_ $$fpeter@observatoire.be
000003407 85642 $$ahttp://www.pnas.org/content/113/41/11431
000003407 85642 $$ahttp://www.pnas.org/content/113/41/11431.full
000003407 85642 $$ahttps://arxiv.org/abs/1609.08633
000003407 905__ $$apublished in
000003407 980__ $$aREFERD