Neutral interstellar gas in the lower galactic halo

Technical Report · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6236521

Albert, C E

The optical interstellar absorpiton lines of Ti II, Ca II, Na I, and the 21 cm emission line of H I were observed at high resolution and high detection sensitivity toward known pairs of nearly aligned distant halo stars and foreground disk stars with well determined distances. Analysis of the column densities, velocities, and the directly determined variation of the titanium abundances with z-distance leads to a general picture of the neutral interstellar material in the lower galactic halo. Two types of gas with distinct distribution, kinematics, and abundances are found, a thick, low velocity disk (type I) extending from the plane to well beyond the thin disk of OB stars, and a high velocity, much less strongly depleted gas (type II) observed only at high z-distances, which constitutes at least 24% of the mass of the halo gas. The implications of this model for the observed neutral gas are discussed both in terms of the possible origins of the observed gas and in its comparison with quasi stellar object absorption lines.

• Research Organization: Chicago Univ., IL (USA)
• OSTI ID: 6236521
• Report Number(s): N-8229246
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTION SPECTRA
ALKALINE EARTH METALS
CALCIUM
CLOUDS
COSMIC DUST
COSMIC GASES
COSMIC RADIO SOURCES
DISTANCE
DUSTS
ELEMENTS
FLUIDS
GALAXIES
GASES
METALS
MILKY WAY
QUASARS
SPECTRA
SPECTROSCOPY
TITANIUM
TRANSITION ELEMENTS
VELOCITY