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Title: The dynamics of the multi-planet system orbiting Kepler-56

Abstract

Kepler-56 is a multi-planet system containing two coplanar inner planets that are in orbits misaligned with respect to the spin axis of the host star, and an outer planet. Various mechanisms have been proposed to explain the broad distribution of spin-orbit angles among exoplanets, and these theories fall under two broad categories. The first is based on dynamical interactions in a multi-body system, while the other assumes that disk migration is the driving mechanism in planetary configuration and that the star (or disk) is titled with respect to the planetary plane. Here we show that the large observed obliquity of Kepler 56 system is consistent with a dynamical origin. In addition, we use observations by Huber et al. to derive the obliquity's probability distribution function, thus improving the constrained lower limit. The outer planet may be the cause of the inner planets' large obliquities, and we give the probability distribution function of its inclination, which depends on the initial orbital configuration of the planetary system. We show that even in the presence of precise measurement of the true obliquity, one cannot distinguish the initial configurations. Finally we consider the fate of the system as the star continues to evolve beyondmore » the main sequence, and we find that the obliquity of the system will not undergo major variations as the star climbs the red giant branch. We follow the evolution of the system and find that the innermost planet will be engulfed in ∼129 Myr. Furthermore we put an upper limit of ∼155 Myr for the engulfment of the second planet. This corresponds to ∼3% of the current age of the star.« less

Authors:
; ;  [1]; ;  [2]
  1. Harvard Smithsonian Center for Astrophysics, Institute for Theory and Computation, 60 Garden Street, Cambridge, MA 02138 (United States)
  2. Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), Northwestern University, Evanston, IL 60208 (United States)
Publication Date:
OSTI Identifier:
22370400
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 794; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DISTRIBUTION; DISTRIBUTION FUNCTIONS; EVOLUTION; INCLINATION; INTERACTIONS; ORBITS; PLANETS; PROBABILITY; SPIN; STARS

Citation Formats

Li, Gongjie, Naoz, Smadar, Johnson, John Asher, Valsecchi, Francesca, and Rasio, Frederic A., E-mail: gli@cfa.harvard.edu, E-mail: snaoz@cfa.harvard.edu. The dynamics of the multi-planet system orbiting Kepler-56. United States: N. p., 2014. Web. doi:10.1088/0004-637X/794/2/131.
Li, Gongjie, Naoz, Smadar, Johnson, John Asher, Valsecchi, Francesca, & Rasio, Frederic A., E-mail: gli@cfa.harvard.edu, E-mail: snaoz@cfa.harvard.edu. The dynamics of the multi-planet system orbiting Kepler-56. United States. doi:10.1088/0004-637X/794/2/131.
Li, Gongjie, Naoz, Smadar, Johnson, John Asher, Valsecchi, Francesca, and Rasio, Frederic A., E-mail: gli@cfa.harvard.edu, E-mail: snaoz@cfa.harvard.edu. Mon . "The dynamics of the multi-planet system orbiting Kepler-56". United States. doi:10.1088/0004-637X/794/2/131.
@article{osti_22370400,
title = {The dynamics of the multi-planet system orbiting Kepler-56},
author = {Li, Gongjie and Naoz, Smadar and Johnson, John Asher and Valsecchi, Francesca and Rasio, Frederic A., E-mail: gli@cfa.harvard.edu, E-mail: snaoz@cfa.harvard.edu},
abstractNote = {Kepler-56 is a multi-planet system containing two coplanar inner planets that are in orbits misaligned with respect to the spin axis of the host star, and an outer planet. Various mechanisms have been proposed to explain the broad distribution of spin-orbit angles among exoplanets, and these theories fall under two broad categories. The first is based on dynamical interactions in a multi-body system, while the other assumes that disk migration is the driving mechanism in planetary configuration and that the star (or disk) is titled with respect to the planetary plane. Here we show that the large observed obliquity of Kepler 56 system is consistent with a dynamical origin. In addition, we use observations by Huber et al. to derive the obliquity's probability distribution function, thus improving the constrained lower limit. The outer planet may be the cause of the inner planets' large obliquities, and we give the probability distribution function of its inclination, which depends on the initial orbital configuration of the planetary system. We show that even in the presence of precise measurement of the true obliquity, one cannot distinguish the initial configurations. Finally we consider the fate of the system as the star continues to evolve beyond the main sequence, and we find that the obliquity of the system will not undergo major variations as the star climbs the red giant branch. We follow the evolution of the system and find that the innermost planet will be engulfed in ∼129 Myr. Furthermore we put an upper limit of ∼155 Myr for the engulfment of the second planet. This corresponds to ∼3% of the current age of the star.},
doi = {10.1088/0004-637X/794/2/131},
journal = {Astrophysical Journal},
number = 2,
volume = 794,
place = {United States},
year = {Mon Oct 20 00:00:00 EDT 2014},
month = {Mon Oct 20 00:00:00 EDT 2014}
}
  • We report the discovery of one newly confirmed planet (P = 66.06 days, R {sub P} = 2.68 ± 0.17 R {sub ⊕}) and mass determinations of two previously validated Kepler planets, Kepler-289 b (P = 34.55 days, R {sub P} = 2.15 ± 0.10 R {sub ⊕}) and Kepler-289-c (P = 125.85 days, R {sub P} = 11.59 ± 0.10 R {sub ⊕}), through their transit timing variations (TTVs). We also exclude the possibility that these three planets reside in a 1:2:4 Laplace resonance. The outer planet has very deep (∼1.3%), high signal-to-noise transits, which puts extremely tight constraintsmore » on its host star's stellar properties via Kepler's Third Law. The star PH3 is a young (∼1 Gyr as determined by isochrones and gyrochronology), Sun-like star with M {sub *} = 1.08 ± 0.02 M {sub ☉}, R {sub *} = 1.00 ± 0.02 R {sub ☉}, and T {sub eff} = 5990 ± 38 K. The middle planet's large TTV amplitude (∼5 hr) resulted either in non-detections or inaccurate detections in previous searches. A strong chopping signal, a shorter period sinusoid in the TTVs, allows us to break the mass-eccentricity degeneracy and uniquely determine the masses of the inner, middle, and outer planets to be M = 7.3 ± 6.8 M {sub ⊕}, 4.0 ± 0.9M {sub ⊕}, and M = 132 ± 17 M {sub ⊕}, which we designate PH3 b, c, and d, respectively. Furthermore, the middle planet, PH3 c, has a relatively low density, ρ = 1.2 ± 0.3 g cm{sup –3} for a planet of its mass, requiring a substantial H/He atmosphere of 2.1{sub −0.3}{sup +0.8}% by mass, and joins a growing population of low-mass, low-density planets.« less
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  • Kepler-91b is a rare example of a transiting hot Jupiter around a red giant star, providing the possibility to study the formation and composition of hot Jupiters under different conditions compared to main-sequence stars. However, the planetary nature of Kepler-91b, which was confirmed using phase-curve variations by Lillo-Box et al., was recently called into question based on a re-analysis of Kepler data. We have obtained ground-based radial velocity observations from the Hobby-Eberly Telescope and unambiguously confirm the planetary nature of Kepler-91b by simultaneously modeling the Kepler and radial velocity data. The star exhibits temporally correlated noise due to stellar granulation whichmore » we model as a Gaussian Process. We hypothesize that it is this noise component that led previous studies to suspect Kepler-91b to be a false positive. Our work confirms the conclusions presented by Lillo-Box et al. that Kepler-91b is a 0.73 ± 0.13 M {sub Jup} planet orbiting a red giant star.« less
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