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Interstellar medium and the highly ionized species observed in the spectrum of the nearby white dwarf G191-B2B

Journal Article · · Astrophys. J., Lett. Ed.; (United States)
DOI:https://doi.org/10.1086/183639· OSTI ID:6115385

High-resolution spectra of the neargy (48 pc) white dwarf G191-B2B obtained with the International Ultraviolet Explorer (IUE) reveal sharp resonance lines of N V, C IV, and Si IV. The origin of these features is most likely linked to the white dwarf, possibly being formed in an expanding halo around the star. Interstellar lines of C II, N I, Mg II, Si II, Fe II are also seen in the spectrum. Analysis of these features indicates an average neutral hydrogen number density, n/sub Htsi/ = 6.4 x 10/sup -3/, for this line of sight. In combination with the recent EUV and soft X-ray results, we interpret this to mean that the interstellar medium in the most immediate solar vicinity is of the ''normal'' density (nroughly-equal0.1 cm/sup -3/) of lower ionization, while just beyond it, at least in some directions, is a hot, lower density plasma. These results are apparently in conflict with the model of the interstellar medium by McKee and Ostriker in its present form.

Research Organization:
Astronomy Department, Computer Sciences Corporation
OSTI ID:
6115385
Journal Information:
Astrophys. J., Lett. Ed.; (United States), Journal Name: Astrophys. J., Lett. Ed.; (United States) Vol. 248:3; ISSN AJLEA
Country of Publication:
United States
Language:
English