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Variations in polarization efficiency (p/A) of interstellar grains as a function of environment place vital constraints on models for the mechanism of their alignment. We use polarimetry of background field stars to investigate alignment in…

Astrophysics · Physics 2009-10-28 P. A. Gerakines , D. C. B. Whittet

A detailed study of interstellar polarization efficiency toward molecular clouds is used to attempt discrimination between grain alignment mechanisms in dense regions of the ISM. Background field stars are used to probe polarization…

Astrophysics · Physics 2008-11-26 D. C. B. Whittet , J. H. Hough , A. Lazarian , Thiem Hoang

The polarization of starlight and thermal dust emission, resulting from non-spherical grains aligned with the interstellar magnetic field (B-field), act as a powerful tool to trace the B-field morphologies and strengths in molecular clouds…

Astrophysics of Galaxies · Physics 2026-05-26 Saikhom Pravash

The alignment of dust grains with the ambient magnetic field produces polarization of starlight as well as thermal dust emission. Using the archival SOFIA/HAWC+ polarimetric data observed toward $\rho$ Ophiuchus (Oph) A cloud hosted by a B…

Astrophysics of Galaxies · Physics 2021-01-25 Le Ngoc Tram , Thiem Hoang , Hyeseung Lee , Fabio Santos , Archana Soam , Pierre Lesaffre , Antoine Gusdorf , William Reach

We have investigated the grain alignment and dust properties towards the direction of the cluster NGC 2345 using the multi-band optical polarimetric observations. For the majority of the stars, the observed polarization is found to be due…

Astrophysics of Galaxies · Physics 2022-06-01 Sadhana Singh , Jeewan C. Pandey , Thiem Hoang

The dependence of polarization fraction $p$ on total intensity $I$ in polarized submillimeter emission measurements is typically parameterized as $p\propto I^{-\alpha}$ $(\alpha \leq 1)$, and used to infer dust grain alignment efficiency in…

The properties of polarization in scattered light by aligned ellipsoidal grains are investigated with the Fredholm integral equation method (FIM) and the T-matrix method (Tmat), and the results are applied to the observed circular…

Astrophysics of Galaxies · Physics 2010-01-15 Masafumi Matsumura , Pierre Bastien

We study alignment of grains by radiative torques. We found steep rise of radiative torque efficiency as grain size increases. This allows larger grains that are known to exist within molecular clouds to be aligned by the attenuated and…

Astrophysics · Physics 2009-11-11 J. Cho , A. Lazarian

It is well known that the polarized continuum emission from magnetically aligned dust grains is determined to a large extent by local magnetic field structure. However, the observed significant anticorrelation between polarization fraction…

Astrophysics of Galaxies · Physics 2019-10-02 Patrick K. King , Che-Yu Chen , Laura M. Fissel , Zhi-Yun Li

Thermal dust continuum polarimetry is a powerful indirect probe of magnetic field geometry in dense molecular clouds while at the same time providing information on the alignment of dust grains with the magnetic field. The leading theory of…

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…

Astrophysics of Galaxies · Physics 2012-08-23 B. -G. Andersson

Grain alignment theory has reached the stage where quantitative predictions of the degree of alignment and its variations with optical depth are possible. With the goal of studying the effect of clumpiness on the sub-millimeter and far…

Astrophysics · Physics 2011-02-11 T. J. Bethell , A. Chepurnov , A. Lazarian , J. Kim

Polarization carries information about the magnetic fields in interstellar clouds. The observations of polarized dust emission are used to study the role of magnetic fields in the evolution of molecular clouds and the initial phases of…

Astrophysics of Galaxies · Physics 2015-05-13 V. -M. Pelkonen , M. Juvela , P. Padoan

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…

Astrophysics · Physics 2016-08-30 A. Lazarian , J. Cho

Dust polarization induced by aligned non-spherical grains acts as an important tool to trace the magnetic field (B-field) morphologies and strengths in molecular clouds and constrain grain properties and their alignment mechanisms. The…

Astrophysics of Galaxies · Physics 2026-03-03 Saikhom Pravash , Thiem Hoang , Archana Soam , Qi-Lao Gu , Tie Liu , Pham Ngoc Diep , Le Ngoc Tram , Nguyen Bich Ngoc

We interpret the relation between the polarizing efficiency $P_{\max}/E(B-V)$ and the wavelength of the maximum polarization $\lambda_{\max}$ observed for 17 objects (including 243 stars) separated into two groups: "dark clouds" and "open…

Astrophysics of Galaxies · Physics 2016-10-12 N. V. Voshchinnikov , V. B. Il'in , H. K. Das

Alignment of dust grains in astrophysical environments results in the polarization of starlight as well as the polarization of radiation emitted by dust. We demonstrate the advances in grain alignment theory allow the use of linear and…

Astrophysics of Galaxies · Physics 2019-10-02 A Lazarian , Thiem Hoang

We present a new method for using the observed starlight polarization and polarized submm emission to constrain the shapes and porosities of interstellar grains. We present the modified picket fence approximation (MPFA), and verify that it…

Astrophysics of Galaxies · Physics 2021-10-04 B. T. Draine , Brandon S. Hensley

The polarisation of light induced by aligned interstellar dust serves as a significant tool in investigating cosmic magnetic fields, dust properties, and poses a challenge in characterising the polarisation of the cosmic microwave…

The optical and near-infrared (OIR) polarization of starlight is typically understood to arise from the dichroic extinction of that light by dust grains whose axes are aligned with respect to a local magnetic-field. The size distribution of…

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