Determination of Be ST parameters from uvby-beta photometry and H-alpha equivalent widths.

We present a procedure to obtain the uvby photometric indices for the underlying stars of Be type objects, corrected for circumstellar emission, from uvby photometry and Ha equivalent width measurements. Corrected indices can be used to determine intrinsic colours, fundamental astrophysical parameters and interstellar reddening by means of the usual uvby calibrations. We have used a sample of Be stars with available uvbyβ and Hα data in order to check our results. A comparison is made between our interstellar reddening determinations and previously published values, obtaining a good agreement.

A preliminary method to correct the β index for circumstellar emission and obtain the absolute magnitudes and distances is also proposed. Finally, we present a discussion on the differentiation between Be stars and supergiant B type stars, which also show Balmer line emission.