Available from UMI in association with The British Library. Requires signed TDF. A high resolution spectrograph has been designed and built at Queen's University to operate at resolving powers ~10^5 in the middle ultraviolet. In particular this instrument has been designed to investigate the absorption profiles of the resonance lines of neutral Mg (2850A) and singly ionized Mg (2795, 2802A) formed in the interstellar gas. These observations are made at an altitude ~40km from a star stabilized balloon platform (S.B.P.). The optical design of the instrument was therefore influenced by the pointing performance specifications of this common-user observational platform. Incorporated in the spectrograph is a compact u.v. detector system utilizing photo-electronic imaging devices. This detector also provides important speed and D.Q.E. gains in the recording of spectra. Two proving flights of the S.B.P. with this spectrograph in the autumn of 1978 have provided some of the highest resolution studies of u.v. interstellar line profiles. The multiple component absorption clearly identified in these lines has allowed an important comparison to be made with corresponding features seen in ground-based visible observations. A strong correlation is evident between the interstellar distribution of Mg and Na along the line of sight to several stars in the Orion association. Satellite observations (IUE) have also proved complementary to some of the work in this investigation.
- Pub Date:
- Physics: Astronomy and Astrophysics