obliquity

Infer the stellar obliquity distribution of transiting planet systems, following Morton & Winn (2014).

Makes use of the simpledist package, which will be installed as a dependency with installation of this package.

There are two main tasks this package does:

1. Calculate posteriors of cos(I) given measurements of Rstar, Prot, Vsin(I).
2. Infer the Fisher distribution parameter $kappa$ given a sample of cos(I) posteriors.

See below for a quick intro, and the notebook demo for more.

Installation

$ pip install [--user] obliquity

Or clone the repository and install:

$ git clone https://github.com/timothydmorton/obliquity.git
$ cd obliquity
$ python setup.py install [--user]

Basic usage

from obliquity.distributions import Cosi_Distribution
cosi_dist = Cosi_Distribution((1.3,0.1),(15,0.3),(3.5,0.5)) #Radius, Prot, VsinI
cosi_dist.summary_plot()

Command-line scripts

In addition to the obliquity module, this package also installs a few command-line scripts:

• write_cosi_dist: This calculates a Cosi_Distribution given input parameters, and writes the distribution to file (.h5 format that can be easily re-loaded back). e.g.,
• calc_kappa_posterior: Calculates the $kappa$ posterior for a sample defined by a given list of cos(I) posteriors.

Some example usage:

$ write_cosi_dist test.h5 -R 1.3 0.1 -P 14 0.3 -V 4 0.5

After having done this, you could launch up python and read in the distribution as follows:

from obliquity import Cosi_Distribution_FromH5
cosi_dist = Cosi_Distribution_FromH5('test.h5')
cosi_dist.summary_plot()

This is particularly useful for running batch jobs and doing more analysis later; for example, you may make a number of .h5 files in this manner, and then analyze them together using calc_kappa_posterior.