Notes. Temperature, frequency exponent, and bolometric luminosity for the sources considered as Class 0 and Class I protostars. For Class I objects, T and β refer to the fit to the longer wavelengths, which can be assimilated to the envelope/outer disk, while the luminosity is in all cases the integrated bolometric luminosity derived from the full SED, without applying additional corrections. The luminosity integration was performed assuming that the object can be reproduced by a sum of black-bodies with different temperatures to extrapolate the emission at longer and shorter wavelengths. Typical errors are in the range 10−20%. More uncertain values (usually due to the uncertainty of the photometry and/or to the lack of observations at longer wavelengths) are marked by “:”. The envelope temperature of G-122 and IRS 6a/b cannot be determined because of the lack of submillimeter data, while the long wavelength SEDs of V 710 and IRAS 18598 can be fitted with different values of T and β.