Copernicus observations of distant unreddened stars. I. Line of sight to MU Colombae and HD 28497

Journal Article · Tue Feb 01 04:00:00 EST 1977 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/154990· OSTI ID:7304739

Shull, J M; York, D G

Copernicus UV data on interstellar lines toward ..mu.. Col and HD 28497 are analyzed to study the abundances and physical conditions in the many components found in each line of sight. Despite low mean neutral hydrogen densities toward these stars, a substantial portion of the neutral gas is associated with dense condensations containing H/sub 2/. In several high-velocity components, Fe, Ca, and possibly Si appear to be nearer their cosmic abundances than is typical in interstellar gas; this effect may be related to the correlation of N (Ca II)/N (Na I) with cloud velocity, and suggests a grain-disruption model. Low-velocity ionized gas with n/sub e/=0.1 to 0.3 cm/sup -3/ appears to be associated with an extended H II region near ..mu.. Col; ionized gas of similar density is seen at the same velocities as the four neutral components toward HD 28497. Si III absorption, with a wide profile at high negative velocities, unaccompanied by any detectable Si II, N II, or neutral gas, is reported in both stars. The observed Si III column densities and velocity fields may be explained by collisionally ionized gas at 30,000 to 100,000 K behind radiatively cooling strong shocks.

• Research Organization: Princeton University Observatory
• OSTI ID: 7304739
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 211:3; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COOLING
COSMIC DUST
COSMIC GASES
COSMIC RADIO SOURCES
DUSTS
ELECTRON DENSITY
FINE STRUCTURE
FLUIDS
FUNCTIONS
GASES
H2 REGIONS
INTERSTELLAR SPACE
IONIZATION
RADIAL VELOCITY
RADIATIVE COOLING
SHOCK WAVES
SPACE
SPECTRA
SPECTRAL DENSITY
SPECTRAL FUNCTIONS
STARS
ULTRAVIOLET SPECTRA
VELOCITY