gas.py 文件源码

def photo_lengthscale(species, source=None):
    """Photodissociation lengthscale for a gas species.

    Parameters
    ----------
    species : string
      The species to look up.
    source : string, optional
      Retrieve values from this source (case insensitive).  See
      references for keys.

    Returns
    -------
    gamma : astropy Quantity
      The lengthscale at 1 au.

    Example
    -------
    >>> from sbpy.activity import photo_lengthscale
    >>> gamma = photo_lengthscale('OH')

    References
    ----------

    [CS93] H2O and OH from Table IV of Cochran & Schleicher 1993,
    Icarus 105, 235-253.  Quoted for intermediate solar activity.

    """

    data = {   # (value, {key feature: ADS bibcode})
        'H2O': { 'CS93': (2.4e4 * u.km, {'H2O photodissociation lengthscale': '1993Icar..105..235C'})},
         'OH': { 'CS93': (1.6e5 * u.km, {'OH photodissociation lengthscale': '1993Icar..105..235C'})},

    }

    default_sources = {
        'H2O': 'CS93',
        'OH': 'CS93',
    }

    assert species.upper() in data, "No timescale available for {}.  Choose from: {}".format(
        species, ', '.join(data.keys()))

    gas = data[species.upper()]
    source = default_sources[species.upper()] if source is None else source

    assert source.upper() in gas, 'Source key {} not available for {}.  Choose from: {}'.format(
        source, species, ', '.join(gas.keys()))

    gamma, bibcode = gas[source.upper()]
    bib.register('activity.gas.photo_lengthscale', bibcode)

    return gamma