Rocket and satellite observations of the local interstellar medium
The purpose of the study described in this thesis was to obtained new information on the structure of the local interstellar medium (ISM). Two separate experiments using different instruments were used in this study. The first experiment employed a spectrometer with a spectral bandpass from 350-1150 {angstrom} which was placed at the focus of a 95 cm, f/2.8 normal incidence telescope flown on an Aries sounding rocket. The purpose of this experiment was to measure the interstellar absorption edges, due to neutral helium and neutral hydrogen, in the spectrum of a hot white dwarf. The hot white dwarf G191-B2B was observed for 87 seconds during the flight. Unfortunately, due to high pressure in the rocket, no scientifically useful data was obtained during the flight. The second experiment utilized the high resolution spectrometer on the International Ultraviolet Explorer satellite. The purpose of the experiment was to observe interstellar absorption lines in the spectrum of hot white dwarfs. A new method of determining the equivalent widths of absorption lines and their uncertainties was developed. The neutral hydrogen column density is estimated from the N I, Si II, and C II columns. Unfortunately, the uncertainties in the neutral hydrogen columns are very large, only two are constrained to better than an order of magnitude. High ionization species (N V, Si IV, and C IV) are seen in five of the stars. Upper limits to the temperature of the ISM are determined from the velocity dispersions. The temperature of the low ionization gas toward four of the stars is constrained to be less than 50,000 K.
- Research Organization:
- California Univ., Berkeley, CA (USA)
- OSTI ID:
- 7193614
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Interstellar medium and the highly ionized species observed in the spectrum of the nearby white dwarf G191-B2B
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Related Subjects
GENERAL PHYSICS
INTERSTELLAR SPACE
MORPHOLOGY
ABSORPTION SPECTRA
ABUNDANCE
DENSITY
HELIUM
HYDROGEN
IONIZATION
IONIZED GASES
LIMITING VALUES
SPECTROMETERS
TEMPERATURE MEASUREMENT
WHITE DWARF STARS
DWARF STARS
ELEMENTS
FLUIDS
GASES
MEASURING INSTRUMENTS
NONMETALS
PHYSICAL PROPERTIES
RARE GASES
SPACE
SPECTRA
STARS
640105* - Astrophysics & Cosmology- Galaxies