Welcome to the exoatmos_lib GitHub page!
This README file is a quick tutorial on how to generate the library of exoplanet atmosphere models using the Python codes provided in this repository.
The exoatmos_lib library consists of modelled transmission and emission spectra of exoplanets, for clear atmospheres, and modulable ranges of equilibrium temperature, presence and abundance of molecular species, planetary radius, and planetary mass. The full library exoatmos_lib is stored on the IAP (Institut d'Astrophysique de Paris) exoatmos server at the filepath /mnt/globalNS/tmp/bessette/exoatmos_lib/.The spectra in this library are of high resolution and are modelled using the petitRADTRANS package. This package offers two resolution modes: the low resolution mode (or 'c-k' mode of (λ/Δλ=1000)), and the high resolution mode (or 'lbl' mode of (λ/Δλ=10^6)).
This GitHub page contains the following:
- mini-lib: folder containing 9 FITS files of transmission and emission spectra modelled in 'c-k' mode.
- mini-lib_lbl: folder containing 9 FITS files of transmission and emission spectra modelled in 'lbl' mode.
- create_db.py: Python file that must be run after downloading any of the libraries (
mini-lib,mini-lib_lbl, orexoatmos_lib) to redefine local path of files in the databasedb.json. - exoatmos_params.py: Python file where input parameters can be changed. By default parameters are set to those representing the exoplanet HD 189733 b.
- exoatmos_params_full-lib.py: Python file where input parameters can be changed. Here the parameters are set to those representing an average Hot Jupiter planet.
- exoatmoslib.py: Python file containing functions useful to the calculation of the library.
- generate_library.py: Python file used to generate library, as a function of the input parameters given in Python file called exoatmos_params.py
- generate_spectrum.py: Python file used to generate an individual spectrum of the library.
- models_lib.py: Python file containing functions useful to the calculation of the library.
- select_models.py: Python file used to select nearest entry of the library or interpolate, as a function of the input parameters given in Python file called exoatmos_params.py and the options given in the command line.
Disk space needed is as follows: 140.0 Mb for the content of this GitHub page, 20.65 Gb for the full scale library, 4.3 Gb for the opacity files in c-k mode, and 240 Gb for the opacity files in lbl mode. Opacity files and installation of petitRADTRANS are available at https://petitradtrans.readthedocs.io/en/latest/.
Note that the full scale library exoatmos_lib as it is defined in exoatmos_params_full-lib.py takes around 9.5 hours to run per molecule.
GUIDE to simple use:
The following depencies should be installed:
numpy, scipy, astropy, matplotlib, optparse, json, copy, petitRADTRANS, glob, os, sys.
Below is an example to generate and plot a model spectrum using petitRADTRANS (please note that the spectrum is generated in c-k mode):
python generate_spectrum.py --output='H2O_CO2_CH4_CO_T1100_ab-3.0_-6.0_-7.5_-3.0_Rp1.14_Mp1.14.fits' --teq=1100 --rp=1.14 --mp=1.14 --species='H2O CO2 CH4 CO' --abundances="-3. -6 -7.5 -3" -p
The following routine generates a library called "mini-lib" of models using the parameters in exoatmos_params.py:
python generate_library.py --libdir=./mini-lib/
Mini-versions of the library mini-lib and mini-lib_lbl were made available here to allow for testing of routines to manage the library.
One can test access to the mini-library mini-lib.py by the following command:
python select_model.py --db=mini-lib/db.json --teq=1132 --ab=-3.4 --rp=1.25 --mp=1.81 --species='H2O' -vn
which returns the following:
Selected model: mini-lib/H2O_T1100_ab-3.00_Rp1.138_Mp1.142.fits
Transmission and emission spectra present in the library and produced with petitRADTRANS look like the following two spectra (please note that the spectra are generated in lbl mode).
The transmission spectrum has the transit radius as its y-axis quantity, as it is a good parameter to measure transmission: as transmission increases, the atmosphere is more transparent, and so the visible radius of the planet + atmosphere decreases. By having the wavelength on the x-axis, one can quickly see at which values of wavelength the transmission is more prominent or not, thus making it easier to characterise the atmosphere. The positive slope of the graph is due to the continuum absorption of the most abundant species, here: hydrogen and helium. An example transmission spectrum can be seen below:
The emission spectrum has the quantity of planetary flux on its y-axis, to be able to study the contribution of light from the planet only. It also possesses wavelength on its x-axis, to be able to retrieve the contribution of different chemical molecules. The slight increase in slope in the graph is due to the emitted temperature of black-body radiation, which makes the planetary flux increase with increasing wavelength. An example emission spectrum can be seen below:
