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A recently discovered filament of polarized starlight that traces a coherent magnetic field is shown to have several properties that are consistent with an origin in the outer heliosheath of the heliosphere: (1) The magnetic field that…

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…

Astrophysics of Galaxies · Physics 2018-01-31 Thiem Hoang , Jungyeon Cho , A. Lazarian

High angular resolution observations of Class 0 protostars have produced detailed maps of the polarized dust emission in the envelopes of these young embedded objects. Interestingly, the improved sensitivity brought by ALMA has revealed…

Astrophysics of Galaxies · Physics 2023-03-29 Valentin J. M. Le Gouellec , Anaëlle J. Maury , Charles L. H. Hull

Several sets of data show that small interstellar grains captured in interstellar magnetic fields draped over the heliosphere appear to polarize the light of nearby stars. The maximum polarization direction is offset in ecliptic longitude…

Astrophysics · Physics 2007-05-23 Priscilla C. Frisch

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…

Astrophysics of Galaxies · Physics 2022-04-06 Thiem Hoang

Our current understanding of interstellar dust is summarized at an introductory level. Submicron-sized interstellar dust grains absorb and scatter light, and reradiate the absorbed energy in the infrared. The grain population spans a range…

Astrophysics · Physics 2009-10-31 B. T. Draine

Interstellar grain alignment studies are currently experiencing a renaissance due to the development of a new quantitative theory based on Radiative Alignment Torques (RAT). One of the distinguishing predictions of this theory is a…

Astrophysics of Galaxies · Physics 2015-05-30 B-G Andersson , O. Pintado , S. B. Potter , V. Straizys , M. Charcos-Llorens

We show that grains can be efficiently aligned by interacting with a subsonic gaseous flow. The alignment arises from grains having irregularities that scatter atoms with different efficiency in the right and left directions. The grains…

Astrophysics · Physics 2009-11-13 Alex Lazarian , Thiem Hoang

Thermal dust polarization is a powerful tool to probe magnetic fields ($\textbf{B}$) and grain properties. However, a systematic study of the dependence of dust polarization on grain properties in protostellar environments is not yet…

Astrophysics of Galaxies · Physics 2024-03-14 Nguyen Chau Giang , Thiem Hoang

Dust grains emit intrinsic polarized emission if they are elongated and aligned in the same direction. The direction of the grain alignment is determined by external forces, such as magnetic fields, radiation, and gas flow against the dust…

Earth and Planetary Astrophysics · Physics 2019-04-03 Akimasa Kataoka , Satoshi Okuzumi , Ryo Tazaki

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

Interstellar medium is turbulent and this induces relative motions of dust grains. We calculate relative velocities of charged grains in a partially ionized magnetized gas. We account for anisotropy of magnetohydrodynamic (MHD) turbulence,…

Astrophysics · Physics 2009-11-07 A. Lazarian , Huirong Yan

Recent observation of 850 micron sub-mm polarization from T Tauri disks opens up the possibility of studying magnetic field structure within protostellar disks. The degree of polarization is around 3 % and the direction of polarization is…

Solar and Stellar Astrophysics · Physics 2009-01-21 Jungyeon Cho , A. Lazarian

Earlier studies of grain alignment dealt mostly with interstellar grains that have strong internal relaxation of energy which aligns grain axis of maximum moment of inertia with respect to grain's angular momentum. In this paper, we study…

Astrophysics · Physics 2010-01-15 Thiem Hoang , Alex Lazarian

Magnetic fields are thought to influence the formation and evolution of circumstellar envelopes around evolved stars. Thermal dust polarization from aligned grains is a promising tool for probing magnetic fields and dust properties in these…

Solar and Stellar Astrophysics · Physics 2024-12-05 Bao Truong , Thiem Hoang , Nguyen Chau Giang , Pham Ngoc Diep , Dieu D. Nguyen , Nguyen Bich Ngoc

Polarization-mode observations from the Atacama Large Millimeter/submillimeter Array (ALMA) are powerful tools for studying the dust grain populations in circumstellar disks. Many sources exhibit polarization signatures consistent with…

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.…

Astrophysics · Physics 2015-06-24 A. Lazarian

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

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

We extend and investigate the spheroidal model of interstellar dust grains used to simultaneously interpret the observed interstellar extinction and polarization curves. We compare our model with similar models recently suggested by other…

Astrophysics of Galaxies · Physics 2015-05-14 H. K. Das , N. V. Voshchinnikov , V. B. Il'in
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