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One of the most informative techniques of studying magnetic fields in molecular clouds is based on the use of starlight polarization and polarized emission arising from aligned dust. How reliable the interpretation of the polarization maps…

Astrophysics · Physics 2017-01-18 A. Lazarian

Misaligned circumbinary disks will produce dust traffic jams during alignment or anti-alignment to the binary orbital plane. We conduct a hydrodynamical simulation of an initially misaligned circumbinary disk undergoing polar alignment with…

Earth and Planetary Astrophysics · Physics 2024-11-20 Jeremy L. Smallwood , Rebecca Nealon , Hsi-Wei Yen , Christophe Pinte , Cristiano Longarini , Hossam Aly , Min-Kai Lin

Dust grains play a major role in many astrophysical contexts. They affect the chemical, magnetic, dynamical, and optical properties of their environment, from galaxies down to the interstellar medium, star-forming regions, and…

Astrophysics of Galaxies · Physics 2021-05-18 Pierre Marchand , Vincent Guillet , Ugo Lebreuilly , Mordecai-Mark Mac Low

Magnetic fields play essential roles in protoplanetary disks. Magnetic fields in the disk atmosphere are of particular interest, as they are connected to the wind-launching mechanism. In this work, we study the polarization of the light…

Earth and Planetary Astrophysics · Physics 2022-08-24 Haifeng Yang , Zhi-Yun Li

Investigating the dust grain size and its dependence on substructures in protoplanetary disks is a crucial step in understanding the initial process of planet formation. Spectral indices derived from millimeter observations are used as a…

Earth and Planetary Astrophysics · Physics 2024-10-08 Dafa Li , Yao Liu , Hongchi Wang , Min Fang , Lei Wang

Interstellar dust grains are often aligned. If the grain alignment direction varies along the line of sight, the thermal emission becomes circularly-polarized. In the diffuse interstellar medium, the circular polarization at far-infrared…

Astrophysics of Galaxies · Physics 2025-04-07 B. T. Draine

We study the stability of charged dust grains orbiting a planet and subject to gravity and the electromagnetic force. Our numerical models cover a broad range of launch distances from the planetary surface to beyond synchronous orbit, and…

Earth and Planetary Astrophysics · Physics 2012-01-18 Daniel Jontof-Hutter , Douglas P. Hamilton

We study the effect of anisotropic radiation illumination on the alignment of polycyclic aromatic hydrocarbons (PAHs) and report that cross-sectional mechanism of alignment earlier considered in terms of gas-grain interactions can also be…

Astrophysics of Galaxies · Physics 2018-07-11 Thiem Hoang , A. Lazarian

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…

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 study the linear growth and nonlinear saturation of the "acoustic Resonant Drag Instability" (RDI) when the dust grains, which drive the instability, have a wide, continuous spectrum of different sizes. This physics is generally…

Astrophysics of Galaxies · Physics 2021-12-13 Jonathan Squire , Stefania Moroianu , Philip F. Hopkins

We present observations of a new group of structures in the diffuse Galactic ISM: slender, linear HI features we dub "fibers" that extend for many degrees at high Galactic latitude. To characterize and measure the extent and strength of…

Astrophysics of Galaxies · Physics 2014-06-19 S E Clark , J E G Peek , M E Putman

We investigate the role and behaviour of dust grains in C-type MHD shock waves in weakly ionized, dense molecular clouds. New shock models are presented for steady, oblique C-type shock structures with shock speed v_s=18km/s, n_H=10^5cm^-3,…

Astrophysics · Physics 2009-11-11 Jacqueline F. Chapman , Mark Wardle

A significant fraction of main sequence stars observed interferometrically in the near infrared have slightly extended components that have been attributed to very hot dust. To match the spectrum appears to require the presence of large…

Earth and Planetary Astrophysics · Physics 2016-01-13 George H. Rieke , Andras Gaspar , Nicholas P. Ballering

The alignment of interstellar dust grains is described by the joint distribution function for certain ``internal'' and ``external'' variables, where the former describe the orientation of a grain's axes with respect to its angular momentum,…

Astrophysics · Physics 2015-06-24 W. G. Roberge

The azimuthal polarization patterns observed in some protoplanetary disks by ALMA at millimeter wavelength have raised doubts about their being produced by dust grains aligned with the magnetic field lines. These conclusions were based on…

Astrophysics of Galaxies · Physics 2020-02-26 V. Guillet , J. M. Girart , A. J. Maury , F. O. Alves

Recent observations have shown that circumbinary discs can be misaligned with respect to the binary orbital plane.The lack of spherical symmetry, together with the non-planar geometry of these systems, causes differential precession which…

Earth and Planetary Astrophysics · Physics 2021-03-31 Cristiano Longarini , Giuseppe Lodato , Claudia Toci , Hossam Aly

The origin of polarized emission from protoplanetary disks is uncertain. Three mechanisms have been proposed for such polarized emission: grain alignment with magnetic fields, grain alignment with radiation gradients, and self-scattering of…

In protoplanetary disks, the distribution and abundance of small (sub)micron grains are important for a range of physical and chemical processes. For example, they dominate the optical depth at short wavelengths and their surfaces are the…

Earth and Planetary Astrophysics · Physics 2016-05-25 Sebastiaan Krijt , Fred J. Ciesla

Massive stars, supernovae, and kilonovae are among the most luminous radiation sources in the universe. Observations usually show near- to mid-infrared (NIR--MIR, $\lambda\sim 1-5~\mu$m) emission excess from H\,{\sc ii} regions around young…

Astrophysics of Galaxies · Physics 2019-05-09 Thiem Hoang , Le Ngoc Tram , Hyeseung Lee , Sang-Hyeon Ahn