Exonest: Bayesian Model Selection Applied to the Detection and Characterization of Exoplanets via Photometric Variations

Placek, Ben; Knuth, Kevin H.; Angerhausen, Daniel

doi:10.1088/0004-637x/795/2/112

Cited by 50 publications

(64 citation statements)

References 38 publications

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“…While previous studies have computed Bayes factors using other algorithms (e.g. nested sampling (Feroz et al 2009;Kipping 2013;Placek et al 2014), geometric-path Monte Carlo (Hou et al 2014)), these studies have assumed that the motion can be described as the linear superposition of Keplerian orbits, which is unsuitable for strongly interacting planetary systems such as GJ 876. We believe this study to be the first example of rigorous Bayesian model comparison applied to strongly interacting planetary systems.…”

Section: Summary and Discussionmentioning

confidence: 99%

An empirically derived three-dimensional Laplace resonance in the Gliese 876 planetary system

Nelson

Robertson

Payne

et al. 2015

Mon. Not. R. Astron. Soc.

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We report constraints on the three-dimensional orbital architecture for all four planets known to orbit the nearby M dwarf Gliese 876 based solely on Doppler measurements and demanding long-term orbital stability. Our dataset incorporates publicly available radial velocities taken with the ELODIE and CORALIE spectrographs, HARPS, and Keck HIRES as well as previously unpublished HIRES velocities. We first quantitatively assess the validity of the planets thought to orbit GJ 876 by computing the Bayes factors for a variety of different coplanar models using an importance sampling algorithm. We find that a four-planet model is preferred over a three-planet model. Next, we apply a Newtonian MCMC algorithm to perform a Bayesian analysis of the planet masses and orbits using an n-body model in three-dimensional space. Based on the radial velocities alone, we find that a 99% credible interval provides upper limits on the mutual inclinations for the three resonant planets (Φ cb < 6.20• for the c and b pair and Φ be < 28.5• for the b and e pair). Subsequent dynamical integrations of our posterior sample find that the GJ 876 planets must be roughly coplanar (Φ cb < 2.60• and Φ be < 7.87• ), indicating the amount of planet-planet scattering in the system has been low. We investigate the distribution of the respective resonant arguments of each planet pair and find that at least one argument for each planet pair and the Laplace argument librate. The libration amplitudes in our three-dimensional orbital model supports the idea of the outer-three planets having undergone significant past disk migration.

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Section: Summary and Discussionmentioning

confidence: 99%

An empirically derived three-dimensional Laplace resonance in the Gliese 876 planetary system

Nelson

Robertson

Payne

et al. 2015

Mon. Not. R. Astron. Soc.

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“…The EXONEST software package ( Figure 1) was originally developed as a part of Ben Placek's Ph.D. thesis [15,16]. Written in MATLAB, EXONEST consists of a core set of stellar and planetary models, a nested sampling-based Bayesian inference engine that can utilize the original nested sampling algorithm [17][18][19], the MultiNest variant [20][21][22] and the Metropolis-Hastings Markov chain Monte Carlo (MCMC) sampling algorithm [23,24].…”

Section: Exonestmentioning

confidence: 99%

“…In the future, these options will be selected, or unselected, via a run file and/or a graphical user interface. EXONEST incorporates an efficient orbit integrator, as well as detailed models for four photometric effects: reflected light, thermal emissions, Doppler boosting or beaming and ellipsoidal variations of the host star [15,16]. Both likelihood functions and priors on the parameter values can be specified.…”

Section: Exonestmentioning

confidence: 99%

“…Only for significantly eccentric orbits, with e > 0.3, in which the planet-star distance r(t) changes, thus affecting reflected light, can thermal flux be modeled independently of reflected light [15], assuming that the temperatures on the planet are relatively constant. Observations in multiple bandpasses, such as combining data from both Kepler and TESS, will enable thermal emissions to be distinguished from reflected light [5].…”

Section: Thermal Emissionsmentioning

confidence: 99%

“…The effect can be derived using special relativity resulting in the following formula for the boosted flux [15,16,69]:…”

Section: Doppler Boosting/beamingmentioning

confidence: 99%

See 2 more Smart Citations

EXONEST: The Bayesian Exoplanetary Explorer

Knuth

Placek

Angerhausen

et al. 2017

Entropy

Self Cite

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Abstract:The fields of astronomy and astrophysics are currently engaged in an unprecedented era of discovery as recent missions have revealed thousands of exoplanets orbiting other stars. While the Kepler Space Telescope mission has enabled most of these exoplanets to be detected by identifying transiting events, exoplanets often exhibit additional photometric effects that can be used to improve the characterization of exoplanets. The EXONEST Exoplanetary Explorer is a Bayesian exoplanet inference engine based on nested sampling and originally designed to analyze archived Kepler Space Telescope and CoRoT (Convection Rotation et Transits planétaires) exoplanet mission data. We discuss the EXONEST software package and describe how it accommodates plug-and-play models of exoplanet-associated photometric effects for the purpose of exoplanet detection, characterization and scientific hypothesis testing. The current suite of models allows for both circular and eccentric orbits in conjunction with photometric effects, such as the primary transit and secondary eclipse, reflected light, thermal emissions, ellipsoidal variations, Doppler beaming and superrotation. We discuss our new efforts to expand the capabilities of the software to include more subtle photometric effects involving reflected and refracted light. We discuss the EXONEST inference engine design and introduce our plans to port the current MATLAB-based EXONEST software package over to the next generation Exoplanetary Explorer, which will be a Python-based open source project with the capability to employ third-party plug-and-play models of exoplanet-related photometric effects.

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Exoplanet Research with the Stratospheric Observatory for Infrared Astronomy (SOFIA)

Angerhausen¹

2017

Handbook of Exoplanets

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Exonest: Bayesian Model Selection Applied to the Detection and Characterization of Exoplanets via Photometric Variations

Cited by 50 publications

References 38 publications

An empirically derived three-dimensional Laplace resonance in the Gliese 876 planetary system

An empirically derived three-dimensional Laplace resonance in the Gliese 876 planetary system

EXONEST: The Bayesian Exoplanetary Explorer

Exoplanet Research with the Stratospheric Observatory for Infrared Astronomy (SOFIA)

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