Dust energetics in the gas phases of the interstellar medium - The origin of the Galactic large-scale far-infrared emission observed by IRAS
T. J. Sodroski, E. Dwek, M. G. Hauser, F. J. Kerr;
ApJ, 1989, 336, 762
ABSTRACT: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.
KEYWORDS: cosmic rays, far infrared radiation, interstellar gas, milky way galaxy, molecular clouds, h ii regions, infrared astronomy satellite, interstellar chemistry, o stars, radiation distribution
PERSOKEY:fir, iras, h_i, h+, h2, milky way, ,
CODE: sodroski89