Joseph Weingartner
Email: joe@physics.gmu.edu
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Research Summary
[ Interstellar Medium ]
Joseph Weingartner works on problems related to the interstellar
medium. With collaborators at Princeton, he has developed a detailed
interstellar dust model that reproduces the observed extinction of
starlight and dust emission. He also studies physical processes
involving interstellar grains, particularly their interaction with
starlight and with the interstellar gas. Finally, he is working on
elucidating the physical mechanism whereby nonspherical grains become
aligned with the interstellar magnetic field. An improved
understanding of the alignment process should help astronomers to use
polarized emission from grains as a diagnostic of the magnetic field.
Research Projects:
(September 2002 - August 2003)
Dynamics of grains exposed to radiative torques
Weingartner and Draine (Princeton) have developed a method for
studying the dynamics of grains exposed to radiative torques (due to
the absorption and scattering of starlight by an irregular grain) that
includes the effects of thermal fluctuations coupling the grain
magnetism and rotation. They find that inclusion of thermal
fluctuations can lead to qualitative changes in the dynamics from
previous treatments that did not take this effect into account.
Radiative torques are thought to play a dominant role in the alignment
of grains with the interstellar magnetic field, and future work
employing the method developed here will explore this possibility in
detail.
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