Ake, Thomas B.

Contact Email: ake@pha.jhu.edu
Institute: Johns Hopkins University/Computer Sciences
Corporation
First Coauthor: Andrea K. Dupree
Institute: Harvard-Smithsonian Center for Astrophysics
Second Coauthor: Jeffrey L. Linsky
Institute: JILA, University of Colorado, and NIST
Subject Area: Stellar Atmospheres, Circumstellar Material
Waveband: Far Ultraviolet
Technique: Spectroscopy
Presentation: Oral Presentation (12 mins + 3 mins. for Questions)
Title: The FUSE Cool Star Survey
Abstract: As part of the PI program, the FUSE cool star group has surveyed 9 coronal, non-coronal, and hybrid stars using the LWRS ( $30^{\prime\prime} \times 30^{\prime\prime}$) aperture, providing full wavelength coverage in the FUSE bandpass. Additional stars are being observed with the MDRS ( $4^{\prime\prime} \times 20^{\prime\prime}$) slit for the team D/H program, primarily to obtain intrinsic Lyman $\beta$ profiles. We will discuss the results of this survey, and demonstrate the types of measurements that can be easily made by FUSE and those that are a challenge:

• Line fluxes provide temperature and density diagnostics from 10⁴-10^6.7 K and 10⁸-10¹¹ cm^-3, but checks must be made when using flux ratios from different channels because of possible misalignments. Fe XVIII, formed near 10⁷ K, has been identified.
• Profiles of strong emission lines (e. g., C III, O VI) are easily resolved. They show complexities due to different heating mechanisms, mass motions, and overlying absorption. Time-resolved spectra have been obtained for a stellar flare.
• Weak emission lines once only observed in the Sun are now available, allowing improved determinations of plasma diagnostics. Fluorescence, particularly in Fe II, has been found in luminous stars.