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As part of a concentrated effort to understand and exploit better the seismicproperties of Feige 48, we reestimated its atmospheric parameters using, forthe first time, a self-consistent approach based on the detailed metalabundances that have been determined in previous studies of both its UV andoptical spectrum. We computed a small 3D grid of 150 fully line-blanketed, NLTEmodel atmospheres incorporating the 8 most abundant metals found in theatmosphere of that star. We next compared quantitatively the synthetic spectrathat we calculated from these models with three observed spectra havingdifferent resolutions (1 A, 6 A, and 8.7 A) and wavelength ranges. Our findingsare Teff = 29,890 K, log g = 5.46, and log N(He)/N(H) = -2.88, with very smallformal fitting errors. These estimates are in good agreement with those ofprevious studies, thus showing that the presence of metals do not affectsignificantly the bulk atmospheric properties of Feige 48. We also modeled theHe II line at 1640 A from the STIS spectrum of the star and we found with thisline an effective temperature and a surface gravity that match well the valuesobtained with the optical data. We also present a radial velocity curve basedon several years of observing Feige 48 at the MMT. This curve indicates aprecise orbital period of 8.25 h. Coupled to our discovery of a weak but veryreal periodicity of 8.25 h in the light curve of Feige 48, that was gatheredduring a recent extensive photometric campaign at the Mount Bigelow 1.55 mKuiper Telescope, we conclude that there is a reflection effect in the system,and that the unseen companion is a low mass MS star and not a white dwarf ashas been previously suggested.

Updates on the Pulsating SdB Star Feige 48 through Spectroscopy