Future Studies of the Local Interstellar Medium With Space Telescope and Columbus

Abstract

AbstractThe spectrographs aboard Space Telescope and Columbus will provide important new information about the interstellar medium in the immediate vicinity of the sun. The Space Telescope high resolution spectrograph (HRS) will produce resolutions, λ/Δλ, of about 18,000 and 70,000 with high sensitivity between 1200 and 3200 A and greatly reduced sensitivity between 1060 and 1200 A. The highest resolution is adequate to define the multicomponent nature of interstellar absorption lines and to measure thermal line widths exceeding 3 km s-1 . The Columbus mission is in the planning stages. However, it is likely that the spacecraft will contain spectrographs capable of resolutions of 3 x 104 between 912 and 1200 A and 500 between 100 and 900 A. In the longer wavelength region, the very important lines of 0 VI, S VI, H2, H I , and D I are available for study. In the short wavelength region, lines of He I and II, are observable. If the 3x104 resolution spectrograph can provide extended wavelength coverage to 770 A, lines of Ne VIII which are expected from 8x105 K gas are accessible. Astronomers using the ST HRS and Columbus spectrographs will be able to study a wide range of problems relating to cold, warm, and hot gas in the local ISM. Some of the most important observing projects are described.