Photometric Colours from Spectra of Single Stars
and of Stellar Populations
Joachim Köppen Kiel May 2017
Some brief explanations
- This utility shows the spectrum of a stellar population (blue) composed of a
mixture of main sequence and red giant stars, specified by their contributions,
and the resultant photometric colours. For comparison, the spectrum (green) and
the colours of a blackbody with specified temperature are given.
- Hit the Enter key after entering a new value to display the new results.
- Magenta curves depict the transmission curves of the photometric filters
of the Johnson-Cousins-Glass UBVRIJHKL system (from Landoldt-Börnstein and
Bessell(2005)).
- The magenta and red vertical lines delimit the visible wavelength region.
- All spectra (from PEGASE) are normalized to the same stellar radius. Thus, to
compute the spectral contribution one has to take into account the number of stars
as well as the luminosity (i.e. the radius) of a single star.