Highly Ionized Gas toward $\xi$ Persei
Session 35 -- ISM: Abundances and Dust
Display presentation, Wednesday, June 14, 1995, 9:20am - 6:30pm

## [35.04] Highly Ionized Gas toward $\xi$ Persei

L.M. Haffner, B.D. Savage (U. Wisconsin---Madison), K.R. Sembach (MIT)

We present Goddard High Resolution Spectrograph (GHRS) observations of intermediately and highly ionized gas toward the O7.5 star $\xi$~Persei. Our 3.5 km s$^{-1}$ resolution GHRS absorption line observations cover the resonance lines Si~{\sc iv} $\lambda\lambda$1393,1402; C~{\sc iv} $\lambda\lambda$1548,1550; N~{\sc v} $\lambda\lambda$1238,1242; Al~{\sc iii} $\lambda$1862; and S~{\sc iii} $\lambda$1190. Copernicus Satellite observations of O~{\sc vi} $\lambda$1031 absorption toward this star are also examined to aid our interpretation of the ionized species observed with the GHRS. The Al~{\sc iii} and S~{\sc iii} profiles exhibit a complex behavior, but can be adequately described by two components. One occurs at velocities where high ion absorption is present, while the other appears distinct from high ion observations and may couple to the neutral gas seen toward the star. The absorption profiles of Si~{\sc iv} and C~{\sc iv} can also be explained by a two component model. A narrow, photoionized component occurs at the same velocity as H$\alpha$ emission detected through Fabry-Perot observations of the star and traces $10^4$ K gas. A second, broader component resembles the O {\sc vi} profile and maps out a hotter, collisionally ionized gas. We discuss possible locations for the generation of this second component, including the Local Bubble, collisionally ionized cloud interfaces, and the bow shock around the star. IRAS images near the star show bright, extended emission at the location of $\xi$ Per and may result from the interaction of the powerful stellar wind ($v_\infty \sim 2600$ km s$^{-1}$; $\dot{M}_\odot \sim 3 \times 10^{-7}$ km s$^{-1}$) and runaway stellar velocity ($\sim 70$ km s$^{-1}$) with the surrounding ISM. In such a dynamic environment, these UV observations toward $\xi$ Per provide an excellent probe of this energetic star interacting with its local environment.