pyaneti: a fast and powerful software suite for multiplanet radial velocity and transit fitting

Abstract

Transiting exoplanet parameter estimation from time-series photometry and Doppler spectroscopy is fundamental to study planets' internal structures and compositions.Here we present the code pyaneti, a powerful and user-friendly software suite to perform multi-planet radial velocity and transit data fitting. The code uses a Bayesian approach combined with an MCMC sampling to estimate the parameters of planetary systems. We combine the numerical efficiency of FORTRAN, the versatility of PYTHON, and the parallelization of OpenMP to make pyaneti a fast and easy to use code. The package is freely available at https://github.com/oscaribv/pyaneti.

Three Super-Earths Transiting the Nearby Star GJ 9827

“…It is interesting to note that the transit duration is longest for GJ9827c, and shortest for GJ9827d. This is consistent with the fit's prediction that GJ9827d has a higher impact parameter than either GJ9827b or c. Additional independent MCMC runs were performed by our team using pyaneti (Barragán et al 2017a), with flattened light curves from independent pipelines developed in our group, and the results are within 1σ errors. Note that the high impact parameter of GJ9827d suggests additional planets, if present, are likely to be nontransiting.…”

juliet: a versatile modelling tool for transiting and non-transiting exoplanetary systems

“…Pollacco et al 2006;Nutzman & Charbonneau 2008;Wheatley et al 2013;Burdanov et al 2017;Pepper et al 2018;Bakos 2018) surveys, along with ambitious space-based transit searches (Borucki et al 2010;Ricker et al 2015), has transformed and nurtured the known field today of extrasolar planets. These efforts have not only increased the number of known planets 2012; Parviainen 2015), radial-velocities (see, e.g., Meschiari et al 2009;Wright & Howard 2009;Baluev 2013;Iglesias-Marzoa et al 2015;Malavolta et al 2016;Fulton et al 2018;Faria et al 2018) or both (see, e.g., Bakos et al 2010;Hartman et al 2012;Espinoza et al 2016;Baluev 2018;Barragán et al 2019;Günther & Daylan 2019;Foreman-Mackey et al 2019), some of which even include the modelling of the stellar properties jointly with the modelling of the photometry and radial-velocities (Eastman et al 2013;Eastman 2017;Eastman et al 2019;Hartman et al 2018).…”

“…Before detailing the procedures used by juliet to model the data and showcase the types of analysis it can do, we would like to first motivate how it differentiates itself from existing codes that perform similar tasks and, thus, why such a library is needed. To date and to our knowledge, the seven open-source tools that can perform both photometric and radial-velocity analysis in order to constrain the physical and orbital parameters of a transiting exoplanet are EXOFAST (Eastman et al 2013;Eastman 2017; Eastman 2 https://github.com/nespinoza/juliet et al 2019), exonailer , PlanetPack (Baluev 2018), pyaneti (Barragán et al 2019), PyORBIT (Malavolta et al 2016(Malavolta et al , 2018, allesfitter (Günther & Daylan 2019) and exoplanet (Foreman-Mackey et al 2019). EX-OFAST is one of the most versatile of the tools described: it indeed allows to fit photometry and radial-velocities from different instruments, and even allows to perform the modelling of the stellar properties jointly with the available photometry and radial-velocity measurements.…”

“…This code, however, only allows to account for systematic trends in the photometry via polynomials, and does not allow to fit multiplanetary systems in the photometry. The recently introduced pyaneti (Barragán et al 2019), although allowing to fit multiple planets in both the radial-velocities and transits, it does not allow to handle data obtained from multiple photometric instruments, and does not support the use of Gaussian Processes either in the photometry nor in the radial-velocities. Finally, allesfitter (Günther & Daylan 2019) and exoplanet (Foreman-Mackey et al 2019) are both very similar to juliet -these are projects that were, in fact, developed at about the same time than this one.…”

Detection and characterization of an ultra-dense sub-Neptunian planet orbiting the Sun-like star K2-292

“…To derive precisely the parameters of the HD 119130 system, we model simultaneously the photometric and spectroscopic data using the code pyaneti (Barragán et al 2019). This software computes posterior distributions using Markov chain Monte Carlo methods based on Bayesian analysis.…”