JoJo

• JoJo is a package for modeling the transit light curves of oblate planets and planets with rings.
• jojo_oblate module is used to compute the transiting light curves of oblate planets by using Green's theorem.
• jojo_ring module can compute the transiting light curves of spherical planets with rings, also using Green's theorem. Comparing to the existing code pyPplusS, JoJo_with_ring can be about 5-10 times faster.

Installation

You can install JoJo through:

git clone https://github.com/Flippedx/JoJo
cd JoJo
pip install -e .

Theory

By applying Green’s theorem, the two-dimensional areal integral over the occultation area can be transferred into a one-dimensional line integration over the boundary. The detailed derivation can be found in Liu et al. 2024.

Usage

• The key function is oblate_lc in jojo_oblate.py, which returns the light curves with the given transiting parameters and time series. Now it works only for the quadratic limb-darkening law.

• For comparison, the code to generate quadratic limb-darkening light curves of spherical planets developed by Eastman, Gaudi & Agol 2013 is included in occultquad.py, you can call spherical_lc in jojo_oblate.py to generate the light curve of a spherical planet with the same cross-section of the oblate planet.

• Based on spherical_lc and oblate_lc, ring_lc in jojo_ring.py returns the light curves of a spherical planets with ring given transiting parameters and time series.

See example.ipynb for specific usages.

Future work

• Calculate light curves for planets with rings.
• Applying other LD laws.
• May develop JAX version.
• Improve the documentation.

Reference

Liu et al. 2024