The extreme ultraviolet spectrum of G191 - B2B and the ionization of the local interstellar medium

Journal Article · Wed Aug 01 00:00:00 EDT 1990 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/169081· OSTI ID:6334901

Green, J; Jelinsky, P; Bowyer, S ^[1]

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1. California Univ., Berkeley (USA)

The measurement of the extreme ultraviolet spectrum of the nearby hot white dwarf G191 - B2B is reported. The results are used to derive interstellar neutral column densities of 1.6 + or - 0.2 x 10 to the 18th/sq cm and 9.8 + 2.8 or - 2.6 x 10 to the 16th/sq cm for H I and He I, respectively. This ratio of neutral hydrogen to neutral helium indicates that the ionization of hydrogen along the line of sight is less than about 30 percent unless significant helium ionization is present. The scenario in which the hydrogen is highly ionized and the helium is neutral is ruled out by this observation. 54 refs.

• OSTI ID: 6334901
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 359; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
640105 -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
COSMIC GASES
DWARF STARS
ELECTROMAGNETIC RADIATION
ELEMENTS
EXTREME ULTRAVIOLET RADIATION
FLUIDS
GASES
HELIUM
INTERSTELLAR SPACE
IONIZATION
NONMETALS
RADIATIONS
RARE GASES
SPACE
SPECTRA
STARS
STELLAR ATMOSPHERES
ULTRAVIOLET RADIATION
ULTRAVIOLET SPECTRA
WHITE DWARF STARS