VOSA offers several options to analyze the observed Spectral Energy Distributions and estimate physical properties for the studied objects.
First, observed photometry is compared to synthetic photometry for
different collections of theoretical models or observational templates in two different ways:
The Chi-square fit provides the best
fit model and thus an estimation of the stellar parameters (temperature,
gravity, metallicity, ...). It also estimates a bolometric luminosity using the distance to
the object, the best fit model total flux and the observed photometry.
On the other hand, the Bayesian analysis provides the projected probability
distribution functions (PDFs) for each parameter of the grid of synthetic spectra.
When these analysis tools are applied to observational templates (chi-square and bayes), we obtain an estimation of the Spectral Type too.
Once the best fit values for temperature and luminosity have been
obtained, it is possible to build an HR diagram using isochrones and evolutionary tracks from VO services and making
interpolations to estimate values of the age and mass for each object.