Linelist

The linelist is an important part of every synthetic spectrum, since it includes all information that is line specific.

Line format

PySME knows to types of linelists. A short format, and a long format. The difference between the two is the amount of information contained therein. The short format contains only enough parameters for LTE calculations, while the long format is required for NLTE calculations.

Line parameters

The short format fields are

species:

A string identifier including the element and ionization state or the molecule

atom number:

Identifies the species by the atomic number (i.e. the number of protons)

ionization:

The ionization state of the species, where 1 is neutral (?)

wlcent:

The central wavelength of the line in Angstrom

excit:

The excitation energy in ?

gflog:

The log of the product of the statistical weight of the lower level and the oscillator strength for the transition.

gamrad:

The radiation broadening parameter

gamqst:

A broadening parameter

gamvw:

van der Waals broadening parameter

lande:

The lande factor

depth:

An arbitrary depth estimation of the line

reference:

A citation where this data came from

In addition the long format has the following fields

lande_lower:

The lower Lande factor

lande_upper:

The upper Lande factor

j_lo:

The spin of the lower level

j_up:

The spin of the upper level

e_upp:

The energy of the upper level

term_lower:

The electron configuration of the lower level

term_upper:

The electron configuration of the upper level

error:

An uncertainty estimate for this linedata

Important Note

As far as the radiative transfer code is concerned the ionization is defined as part of the species term. I.e. a line with species = “Fe 2” will be calculated as ionization = 2. If no number is set within the species field, SME will use an ionization of 1.

Also atom_number is ignored in the radiative transfer calculations and therefore does not need to be set.

VALD integration

PySME is designed to be used in combination with VALD3 (http://vald.astro.uu.se/). The easiest way to get a linelist into PySME is therefore to use VALD extract stellar, as that can be directly imported using the ValdFile class.