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Description
The observed spectral variation of HD50138 led different authors in the literature to classify it in a very large range of spectral types and luminosity classes (from B5 to A0 and III to Ia) and at different evolutionary stages, as either an HAeBe star or a classical Be. Based on new high-resolution optical spectroscopic data from 1999 and 2007, we perform a detailed spectral description, presenting the variations seen and discussing their possible origin. We tentatively suggest that a new shell phase could have taken place prior to our observations in 2007. We derive the interstellar extinction to HD50138 by taking into account the influences of the circumstellar matter in the form of dust and an ionized disk. We find a color excess value of E(B-V)=0.08mag. Based on photometric data from the literature and the new Hipparcos distance, we obtain a revised set of parameters for HD50138, suggesting that it is a B6-7 III-V star. A discussion about the different evolutionary scenarios is also provided.
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