Stellar models

The type parameter allows to select from a range of stellar models, either analytical, or available as data files or FITS images. Please note that a new numbering scheme was introduced with Version 6.12 (2 Aug 2007)

For all types from zero to 11, the flux distribution (spectrum) is computed as flat (teff=0), a black body (teff < 0), or derived from a stellar atmosphere (teff > 0). For all types, specifying an arbitrary SED will override stellar spectra or fluxes derived from the images. The XDR file to read is specified in sed, and should restore variables $l$ and $f$, which contain the wavelength in meters and the flux (per wavelength interval), respectively. Please note that if the effective of a component is non-zero, the flux will be scaled with the squared diameter! As mentioned above (readmodel), please keep in mind that an internal value of $-5555$ for an effective temperature is interpreted as zero.

Stellar spectra and limb-darking coefficients as a function of log(g) and teff are from Van Hamme (1993) and are stored in file atmospheres/vanhamme/limbdata.vh.xdr. For stellar temperatures less than 3500 K it is possible to use the NextGen models (http://phoenix.ens-lyon.fr/Grids/) by copying one of the files atmospheres/vanhamme/limbdata.n?.xdr to limbdata.xdr. Please note that the NextGen models do not provide the limb-darkening coefficients! Further information can be found in the file Notes.txt.

In many models, specifying pa and ratio is used to rotate and stretch the $(u,v)$ coordinates. The only exceptions are the images if a positive non-zero diameter of the CLEAN beam have been specified.