The Far-Infrared Polarization Spectrum: First Results and Analysis
R. H. Hildebrand, J. L. Dotson, C. D. Dowell, D. A. Schleuning, J. E. Vaillancourt;
ApJ, 1999, 516, 834
ABSTRACT:We present data on the polarization of the thermal emission from Galactic Clouds at 60 mum, 100 mum, and 350 mum.
There are examples of rising
polarization spectra in dense cloud cores [P(350 mum/P(100 μm)~2], and falling
spectra in cloud envelopes [P(350)/P(100 μm)~0.6].
We also present data
showing that the relationship, P(tau), between polarization and optical
depth in cloud cores is different from that in cloud envelopes.
We review the
principles governing the far-infrared polarization spectrum and discuss
applications to the data on P(lambda) and P(tau).
We conclude that the cloud
envelopes we have observed must contain two populations of grains that differ in
their polarization efficiencies and in their emission spectra.
We propose
a model for cloud envelopes in which the contrasting populations reside
in domains of different mean temperatures where the warmer domains
contain the aligned grains.
KEYWORDS: ism: dust, extinction, infrared: ism: continuum, ism: clouds, polarization, stars: low-mass, brown dwarfs
PERSOKEY:polarisation, dust, fir, ,
CODE: hildebrand99