SPECTRUM is a stellar spectral synthesis program designed for use on a wide range of platforms, including most types of UNIX and Linux. Given a stellar atmosphere model and certain other inputs, SPECTRUM calculates a synthetic stellar spectrum. SPECTRUM carries out this computation under the assumptions of local thermodynamic equilibrium (LTE) and a plane-parallel atmosphere. Currently, SPECTRUM is suitable for computing stellar spectra in the spectral-type range B - mid M.
SPECTRUM may be programmed with command-line switches to give a number of different output formats. For instance, in default mode, SPECTRUM computes the disk-integrated normalized intensity spectrum, but with the appropriate switches, SPECTRUM can be directed to compute either the specific intensity from any point on the stellar surface or the disk-integrated flux. SPECTRUM currently supports all naturally occurring elements, along with a total of 310 isotopes. Hyperfine structure is also supported. In addition, SPECTRUM can handle 15 diatomic molecules important in stellar atmospheres, including TiO and ZrO. Isotopic versions of most of these molecules are also supported.
SPECTRUM comes with a suite of supporting programs, including programs for computing elemental abundances from equivalent widths (ABUNDANCE), a program for simultaneously determining abundances and the microturbulent velocity (BLACKWEL), a program that aids in the identification of stellar spectral lines (LINES), and various other auxiliary programs to convert the output of SPECTRUM to a form that can be compared directly with observations.
Note: This documentation has been written specifically for versions 2.76 and later. For version 2.75, please follow the directions on the main SPECTRUM website for compilation and installation.