The Interstellar Lines of the Feige Stars

Abstract

New measurements of the equivalent widths and radial velocities of the interstellar lines of Ca ii and Na i in the spectra of Feige stars are presented. The upper limits to the Na i interstellar line imply that the gas in the halo has a much larger value of the ratio of the column density of Ca ii to that of Na i than does the plane, and that this ratio is larger than the intermediate value obtained previously from a group of brighter halo stars. From this we deduce that there is gas up to at least 1 kpc above the plane, and that this gas has much more Ca ii relative to Na i than does the plane. The interstellar equivalent width corresponding to looking out of the Galaxy from the plane at b^(II) = 90° is about 300 mÅ for the stronger of the Ca n lines. The velocity measurements imply that this gas is moving slowly toward the plane in a time scale such that replenishment of the halo gas is necessary.

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