The Galactic large-scale far-infrared emission observed by IRAS: Implications for the morphology, physical conditions, and energetics of dust in the interstellar medium

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:5179503

Sodroski, T J

IRAS observations of the 60 and 100 {mu}m Galactic plane emission, from which the contribution of the zodiacal light has been subtracted, are combined with available {sup 12}CO, 5 GHz radio-continuum, and HI observations of the Galactic plane to study the energetics of the dust that gives rise to the Galaxy's large-scale far-infrared emission. Two independent modeling approaches for deriving large-scale Galactic properties are presented. In the first approach, basic physical conditions are derived on the assumption of an isothermal dust distribution along each line of sight in the Galactic plane. In the second approach, longitude-latitude maps of the 60 and 100 {mu}m emission near the Galactic plane are linearly decomposed into three components that are associated with the molecular (H{sub 2}), neutral atomic (HI), and extended low-density (n{sub eff} > 10 cm{sup {minus}3}) ionized (HIII) phases of the interstellar medium. From the resulting emission components, the average large-scale far-infrared properties of each gas phase and the distribution of total Galactic far-infrared luminosity among the three gas phases are derived. It is shown that most (>90%) of the Galaxy's total far-infrared luminosity arises from cold dust associated with clouds of neutral atomic hydrogen (60-75%) and molecular (15-30%) gas. The far-infrared luminosity of dust associated with extended low-density HII regions accounts for only 8-10% of the Galaxy's total far-infrared output. Comparisons of the results with current models of the Galactic large-scale FIR emission are made.

• Research Organization: Maryland Univ., College Park, MD (USA)
• OSTI ID: 5179503
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COMPARATIVE EVALUATIONS
COSMIC DUST
COSMIC GASES
COSMIC RADIO SOURCES
DUSTS
ELECTROMAGNETIC RADIATION
FAR INFRARED RADIATION
FLUIDS
GALAXIES
GASES
H1 REGIONS
H2 REGIONS
HEATING
INFRARED RADIATION
INTERSTELLAR GRAINS
INTERSTELLAR SPACE
IONIZATION
LUMINOSITY
MAPS
MATHEMATICAL MODELS
MILKY WAY
MORPHOLOGY
OPTICAL PROPERTIES
PARTICLES
PHYSICAL PROPERTIES
RADIATIONS
SPACE
STARS