ORFEUS II echelle spectra: The scale height of interstellar O vi in the halo
/ Authors
H. Widmann, K. S. D. Boer, P. Richter, G. Krämer, I. Appenzeller, J. Barnstedt, M. Gölz, M. Grewing, W. Gringel, H. Mandel
and 1 more author
/ Abstract
FUV high resolution spectra of 18 stars, particularly chosen to observe the interstellar medium (ISM), were obtained during the second ORFEUS-SPAS free flight space shuttle mis- sion in December 1996. Among these were 6 objects with a distance to the galactic plane larger than 1 kpc, one SMC and 4 LMC stars. This selction of targets is part of the ORFEUS pro- gram to explore the galactic halo. As the most important tracer of the hot gas we analyzed the stronger component of the impor- tant Ovi doublet in all our ISM spectra. We found an average N (Ovi)sin jbj of 3:5 10 14 cm 2 on the lines of sight to the 4 LMC stars. Assuming an exponential distribution of Ovi we calculated a midplane density n0 of 2:07 +0:26 0:24 10 8 cm 3
Journal: Astronomy and Astrophysics