AAS 198th Meeting, June 2001
Session 45. Stellar Observations with FUSE
Display, Tuesday, June 5, 2001, 10:00am-6:30pm, Exhibit Hall

## [45.02] A FUSE Study of Main Sequence B Stars

E.L. Fitzpatrick (Villanova University), D. Massa (Emergent IT)

We report first results from a study of the spectral energy distributions of mid- to late- main sequence B (BV'') stars utilizing newly acquired (Cycle 2) Far Ultraviolet Spectroscopic Explorer (FUSE) observations, archival IUE data, and ground-based optical photometry. The goal of the program is to perform a comprehensive investigation of the ability of current model atmosphere calculations to reproduce the observed properties of the BVs, including the overall energy distributions and the detailed absorption line spectra. This study will provide a benchmark and a reality check'' for studies of more exotic early-type objects, since the BVs are the hottest and most luminous stars whose atmospheres can be modeled with simplifying assumptions, such as LTE, plane-parallel geometry, and hydrostatic equilibrium. The FUSE targets include 15 members of the Orion OB associations. They span a {\rm Teff} range of 11000-17000 K, a vsini range of nearly 400 km s-1, are lightly reddened to minimize the impact of the ISM, and are located in a relatively small volume of space to minimize differential extinction effects. In the temperature range considered, the FUSE wavelength region (900-1200 Å) constitutes a significant fraction of the total emitted stellar energy and is extraordinarily sensitive to stellar atmosphere conditions.

In this poster we illustrate the UV-through-optical energy distributions of our targets, along with preliminary modeling of the fluxes. We also demonstrate the ability of current spectral synthesis programs to reproduce the detailed far-UV spectra of these stars.