A standard library of theoretical stellar spectra intended for multiple
synthetic photometry applications including spectral evolutionary synthesis is
presented. The grid includes M dwarf model spectra, hence complementing the
first library version established in Paper I (Lejeune, Cuisinier & Buser 1997).
It covers wide ranges of fundamental parameters: Teff : 50,000 K to 2000 K, log
g : 5.5 to -1.02, and [M/H] : +1.0 to -5.0. A correction procedure is also
applied to the theoretical spectra in order to provide color-calibrated flux
distributions over a large domain of effective temperatures. For this purpose,
empirical Teff-color calibrations are constructed between 11500 K and 2000 K,
and semi-empirical calibrations for non-solar abundances ([M/H] = -3.5 to +1.0)
are established. Model colors and bolometric corrections for both the original
and the corrected spectra, synthesized in the UBVRcIcJHKLL'M system, are given
for the full range of stellar parameters. We find that the corrected spectra
provide a more realistic representation of empirical stellar colors, though the
method employed is not completely adapted to the lowest temperature models. In
particular the original differential colors of the grid implied by metallicity
and/or luminosity changes are not preserved below 2500 K. Limitations of the
correction method used are also discussed.Comment: Accepted for publication in A&A Supplement Series (LaTex); 22 pages,
including 8 postscript figures and 10 tables. Also available at
http://www.astro.unibas.ch/~lejeune