CINE: Comet INfrared Excitation

cine is a command-line tool for calculating infrared pumping efficiencies. At large nucleocentric distances, one of the main mechanisms for molecular excitation in comets is the fluorescence by the solar radiation followed by radiative decay to the ground vibrational state. This code calculates the effective pumping rates for rotational levels in the ground vibrational state scaled by the heliocentric distance of the comet. These coefficients are useful for modeling rotational emission lines observed in cometary spectra at sub-millimeter wavelengths.

Code releases are available on PyPI, and development happens in the github project page.

Requirements

The code requires the standard scientific Python packages (numpy, scipy, and pandas) and astropy's affiliated package astroquery to access the HITRAN and Lamda databases. Running the tests requires nose.

Installation

cine can be installed using pip:

$ pip install cine

or by cloning the github repository:

$ # If you have a github account:
$ git clone git@github.com:migueldvb/cine.git
$ # If you do not:
$ git clone https://github.com/migueldvb/cine.git
$ cd cine
$ python setup.py install
$ # Or if you do not have root privileges:
$ python setup.py install --user

When the package is installed using either method, the cine script will be copied to a directory in the PATH environment variable and will be available for general use.

Example

cine is a command-line tool that is included in the package to generate pumping rates for several molecules. For example, to obtain the effective pumping rates between the seven lowest rotational levels in the ground vibrational state of HDO you can run the following command once CINE has been installed:

$ cine --mol HDO --nlevels 7

This should create a file named G_HDO.dat which contains the pumping rates G _ij in units of s ^-1 between the rotational levels i and j shown in the first two columns. Note that the levels use zero-based indexing.

0 3 2.568872e-05
0 4 2.570305e-05
0 5 1.552757e-05
1 2 6.253229e-05
1 6 2.987896e-05
2 1 6.196215e-05
2 6 4.410062e-05
3 0 7.547422e-05
3 4 3.103947e-05
3 5 5.048423e-05
4 0 1.253741e-04
4 3 5.128064e-05
4 5 4.679292e-05
5 0 7.481781e-05
5 3 8.287649e-05
5 4 4.643613e-05
6 1 4.820172e-05
6 2 7.201329e-05

To include more levels in the calculation, change the -n/-nlevels command-line option to a larger value. cine has a -h/--help argument that presents an usage explanation describing each optional argument.

These coefficients are useful for deriving molecular production rates from cometary lines observed at sub-millimeter wavelengths combined with a code that solves the radiative transfer equations such as LIME.

Downloading HITRAN data

To download the molecular data cine uses the astroquery.hitran and astroquery.lamda tools. Set the LAMDA_DATA and HITRAN_DATA environment variables (otherwise, the default ~/.astropy/cache/astroquery/Lamda and ~/.astropy/cache/astroquery/hitran will be used),

Tests

If nose is installed the tests can be run from the root of the repository as:

$ python setup.py test

Contributing

Any questions or bug reports can be raised in github's issue tracker or pull requests.

Project Status

Citation

If you wish to cite this work, please use this reference from NASA's Astrophysics Data System:

@ARTICLE{2017JOSS....2..182D,
       author = {{de Val-Borro}, Miguel and {Cordiner}, Martin A. and {Milam}, Stefanie
        N. and {Charnley}, Steven B.},
        title = "{Cine: Line excitation by infrared fluorescence in cometary atmospheres}",
      journal = {The Journal of Open Source Software},
         year = 2017,
        month = Mar,
       volume = {2},
        pages = {182},
          doi = {10.21105/joss.00182},
       adsurl = {https://ui.adsabs.harvard.edu/#abs/2017JOSS....2..182D},
      adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}

License

Copyright 2017-2018 Miguel de Val-Borro

CINE is free software made available under the MIT License. For details see the LICENSE file.