Dust energetics in the gas phases of the interstellar medium - the origin of the Galactic large-scale far-infrared emission observed by IRAS

Journal Article · Sun Jan 01 04:00:00 EST 1989 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/167048· OSTI ID:6145571

Sodroski, T J; Dwek, E; Hauser, M G; Kerr, F J

The large-scale Galactic properties within the most massive gas phases of the ISM are derived along with the distribution of total Galactic FIR luminosity among the three phases. Most of the Galaxy's total FIR luminosity is found to be emitted by cold dust associated with diffuse H I clouds and molecular gas. The total FIR luminosity of dust associated with extended low-density H II regions accounts for less than 10 percent of the Galaxy's total FIR output. The absence of a significant variation with longitude in the observed temperature of the dust associated with H I gas suggests that diffuse neutral clouds contain very small dust grains that are stochastically heated by the interstellar radiation field. The results are consistent with a model in which most of the FIR luminosity of molecular clouds arises from dust that is associated with giant molecular clouds and heated by embedded and nearby OB stars. H II regions in the inner Galaxy have a mean IR excess ratio of about 2.5, suggesting that the dust in these regions is heated primarily by directly absorbed stellar photons. 85 references.

• Research Organization: NASA, Goddard Space Flight Center, Greenbelt, MD (USA); Maryland Univ., College Park (USA); NASA, Goddard Space Flight Center, Greenbelt, MD (USA)
• OSTI ID: 6145571
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 336; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHEMISTRY
COSMIC DUST
COSMIC GASES
COSMIC RADIO SOURCES
COSMOCHEMISTRY
DUSTS
ELECTROMAGNETIC RADIATION
FAR INFRARED RADIATION
FLUIDS
GALAXIES
GASES
H2 REGIONS
HEATING
INFRARED RADIATION
INTERSTELLAR SPACE
LUMINOSITY
MILKY WAY
OPTICAL PROPERTIES
ORIGIN
PHYSICAL PROPERTIES
RADIATIONS
SPACE