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Session 44 - Double Stars.
Display session, Thursday, January 08
Exhibit Hall,

[44.14] The Pleiades: Energy Distributions and Binaries

N. R. Evans (SAO), R. Pitts (STScI)

We observed 32 of the brightest stars in the Pleiades with IUE in low resolution. Very precise spectral types have been determined for the late B and early A stars by comparing with spectra of Morgan Keenan standard stars. This is confirmed by the very tight main sequence which results from using these spectral types and a magnitude created from the flux from 1350 to 1950 ÅWe are also determining temperatures and bolometric magnitudes by fitting the spectra with Kurucz model atmospheres. We have compared this group of stars with X-ray sources in the Pleiades, recently discussed by Stauffer, et al. (1994, ApJS, 91, 625). Since virtually all G and K stars in the Pleiades have been detected in their ROSAT images, early type stars which do not have X-rays can be assumed not to have late type companions. This puts a strong constraint on the binary fraction of intermediate mass stars with low mass companions.

Program listing for Thursday