# beta_factor¶

sbpy.activity.beta_factor(mol_data, ephemobj)[source]

Returns beta factor based on timescales from gas and distance from the Sun using an ephem object. The calculation is: parent photodissociation timescale * (distance from comet to Sun)**2 If you wish to provide your own beta factor, you can calculate the equation expressed in units of AU**2 * s , all that is needed is the timescale of the molecule and the distance of the comet from the Sun. Once you have the beta factor you can append it to your mol_data phys object with the name ‘beta’ or any of its alternative names.

Parameters
mol_dataphys
sbpy.data.phys object that contains AT LEAST the following data:
mol_tag: Molecular identifier (int or str)

This field can be given by the user directly or found using from_jplspec. If the mol_tag is an integer, the program will assume it is the JPL Spectral Molecular Catalog identifier of the molecule and will treat it as such. If mol_tag is a string, then it will be assumed to be the human-readable name of the molecule. The molecule MUST be defined in sbpy.activity.gas.timescale, otherwise this function cannot be used and the beta factor will have to be provided by the user directly for calculations. The user can obtain the beta factor from the formula provided above. Keywords that can be used for these values are found under fieldnames documentation. We recommend the use of the JPL Molecular Spectral Catalog and the use of from_jplspec to obtain these values in order to maintain consistency. Yet, if you wish to use your own molecular data, it is possible. Make sure to inform yourself on the values needed for each function, their units, and their interchangeable keywords as part of the Phys data class.

ephemobjephem

sbpy.data.ephem object holding ephemeride information including distance from comet to Sun [‘r’] and from comet to observer [‘delta’]

Returns
qQuantity

Beta factor ‘beta’, which can be appended to the original sbpy.phys object for future calculations