The Interstellar Lines of the Feige Stars
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.
Additional Information© American Astronomical Society • Provided by the NASA Astrophysics Data System. Received 1974 November 18; revised 1974 December 27. We are extremely grateful to Drs. R. P. Kraft, K. Anderson, J. L. Greenstein, and W. Sargent for providing the spectra on which this investigation is based.
Published - 1975ApJ___198__545C.pdf