Related papers: Subsonic Mechanical Alignment of Irregular Grains
It is shown, that mechanical alignment can be efficient for suprathermally rotating grains, provided that they drift with supersonic velocities. Such a drift should be widely spread due to both Alfv\'{e}nic waves and ambipolar diffusion.…
Collisions of gas particles with a drifting grain give rise to a mechanical torque on the grain. Recent work by Lazarian & Hoang showed that mechanical torques might play a significant role in aligning helical grains along the interstellar…
This paper provides a quantitative account of a recently introduced mechanism of mechanical alignment of suprathermally rotating grains. These rapidly rotating grains are essentially not susceptible to random torques arising from gas-grain…
Several mechanisms have been proposed to explain the alignment of grains with the interstellar magnetic field, including paramagnetic dissipation, radiative torques, and supersonic gas-grain streaming. These must compete with disaligning…
We study the alignment of irregular dust grains by mechanical torques due to the drift of grains through the ambient gas. We first calculate mechanical torques (MATs) resulting from specular reflection of gas atoms for seven irregular…
We study the efficiency of grain alignment by radiative torques (RATs) for an ensemble of irregular grains. The grains are modeled as ensembles of oblate and prolate spheroids, deformed as Gaussian random ellipsoids, and their scattering…
We present extensive calculations on the efficiency of grain alignment by the Davis-Greenstein mechanism. We model the grains as oblate spheroids with arbitrary axis ratios. Our description of the grain dynamics includes (i) magnetic…
Paramagnetic alignment of non-spherical dust grains rotating at thermal velocities is studied. The analytical solution is found for the alignment measure of oblate grains. Perturbative approach is used for solving the problem. It is shown…
It is shown that mechanical alignment of grains can be efficient for grains rotating suprathermally, i.e. with kinetic energy substantially exceeding $k$ (the Boltzmann constant) over any temperature in the system. The paper studies…
Grain alignment theory suggests that grains should be aligned in circumstellar regions and the observational data available supports this conclusion. We discuss the alignment of grains via (1) magnetic relaxation, (2) mechanical processes,…
Magnetic fields play a crucial role in various astrophysical processes, including star formation, accretion of matter, transport processes (e.g., transport of heat), and cosmic rays. One of the easiest ways to determine the magnetic field…
Paramagnetic alignment of suprathermally rotating grains is discussed in view of recent progress in understanding subtle processes taking place over grain surface. It is shown that in typical ISM conditions, grains with surfaces of…
Aligned grains provide one of the easiest ways to study magnetic fields in diffuse gas and molecular clouds. How reliable our conclusions about the inferred magnetic field depends critically on our understanding of the physics of grain…
Polarimetry is one of the most informative techniques of studying magnetic fields in molecular clouds. How reliable the interpretation of the polarization maps in terms of magnetic fields is the issue that the grain alignment theory…
The measures of mechanical alignment were obtained for both prolate and oblate grains when their temperature is comparable with grain kinetic energy devided by k, the Boltzmann constant. For such grains, the alignment of angular momentum,…
We develop a comprehensive quantitative description of the cross-section mechanism discovered several years ago by Lazarian. This is one of the processes that determine grain orientation in clouds of suprathermal cosmic dust. The…
Interstellar polarization in the optical/infrared has long been known to be due to asymmetrical dust grains aligned with the magnetic field and can potentially provide a resource effective way to probe both the topology and strength of the…
Recent (sub)millimeter polarization observations of protoplanetary disks reveal toroidally aligned, effectively prolate dust grains large enough (at least ~100 $\mu$m) to efficiently scatter millimeter light. The alignment mechanism for…
Dust grains drift through the interstellar medium (ISM) and are aligned with the magnetic field. Here we study the effect of grain alignment and grain motion on grain growth in molecular clouds (MCs). We first discuss the characteristic…
We show that the energy-level splitting arising from grain rotation ensures that paramagnetic dissipation acts at its maximum rate, i.e., the conditions for paramagnetic resonance are automatically fulfilled. We refer to this process as…