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Though flux freezing is a good approximation frequently assumed for molecular clouds, ambipolar diffusion (AD) is inevitable at certain scales. The scale at which AD sets in can be a crucial parameter for turbulence and the star formation…

Solar and Stellar Astrophysics · Physics 2015-05-18 Hua-bai Li , Martin Houde , Shih-ping Lai , T. K. Sridharan

Optical observations cannot resolve the structure of active galactic nuclei (AGN), and a unified model for AGN was inferred mostly from indirect methods. Optical reverberation mapping allowed us to constrain the spatial dimension of the…

High Energy Astrophysical Phenomena · Physics 2017-12-05 P. A. Rojas Lobos , R. W. Goosmann , F. Marin , D. Savić

Magnetic fields play a role in the dynamics of many astrophysical processes, but they are hard to detect. In a partially ionized plasma, a magnetic field works directly on the ionized medium but not on the neutral medium, which gives rise…

Solar and Stellar Astrophysics · Physics 2020-06-24 Boy Lankhaar , Wouter Vlemmings

We study the radial and vertical stability of dust grains launched with all charge-to-mass ratios at arbitrary distances from rotating planets with complex magnetic fields. We show that the aligned dipole magnetic field model analyzed by…

Earth and Planetary Astrophysics · Physics 2012-06-06 Daniel Jontof-Hutter , Douglas P. Hamilton

Accurate temperature calculations for circumstellar disks are particularly important for their chemical evolution. Their temperature distribution is determined by the optical properties of the dust grains, which, among other parameters,…

Solar and Stellar Astrophysics · Physics 2017-07-26 S. Heese , S. Wolf , A. Dutrey , S. Guilloteau

The circumnuclear disc (CND) orbiting the Galaxy's central black hole is a reservoir of material that can ultimately provide energy through accretion, or form stars in the presence of the black hole, as evidenced by the stellar cluster that…

Astrophysics of Galaxies · Physics 2016-04-20 Marvin Blank , Mark R. Morris , Adam Frank , Jonathan J. Carroll-Nellenback , Wolfgang J. Duschl

We present mid-IR interferometric observations of 6 type 1 AGNs at multiple baseline lengths of 27--130m, reaching high angular resolutions up to lambda/B~0.02 arcseconds. For two of the targets, we have simultaneous near-IR interferometric…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Makoto Kishimoto , Sebastian F. Hoenig , Robert Antonucci , Florentin Millour , Konrad R. W. Tristram , Gerd Weigelt

Infrared interferometry has fuelled a paradigm shift in our understanding of the dusty structure in the central parsecs of Active Galactic Nuclei (AGN). The dust is now thought to comprise of a hot ($\sim1000\,$K) equatorial disk, some of…

To test the dust torus model for active galactic nuclei directly, we study the extent and morphology of the nuclear dust distribution in the Circinus galaxy using high resolution interferometric observations in the mid-infrared with the…

Polarized microwave emission from dust is an important foreground that may contaminate polarized CMB studies unless carefully accounted for. Modeling of polarization from dust requires a quantitative understanding of grain alignment. I…

Astrophysics · Physics 2008-11-07 A. Lazarian

The review contains an analysis of the observed and model curves of the interstellar extinction and polarization. The observations mainly give information on dust in diffuse and translucent interstellar clouds. The features of various dust…

Astrophysics of Galaxies · Physics 2015-06-05 N. V. Voshchinnikov

We present a new method to constrain the grain size in protoplanetary disks with polarization observations at millimeter wavelengths. If dust grains are grown to the size comparable to the wavelengths, the dust grains are expected to have a…

In this paper the distribution of charged particles is constructed under the approximation of ambipolar diffusion. The results of mathematical modelling in two-dimensional case taking into account the velocities of the system are presented.

Computational Engineering, Finance, and Science · Computer Science 2007-05-23 P. Nefyodov , V. Reztsov , O. Riabinina

(Abridged) Context. Massive stars form in magnetized and turbulent environments, and are often located in stellar clusters. Their accretion mechanism, as well as the origin of their system's stellar multiplicity are poorly understood. Aims.…

Solar and Stellar Astrophysics · Physics 2021-08-11 R. Mignon-Risse , M. González , B. Commerçon , Joakim Rosdahl

We present a statistical analysis of the properties of the obscuring material around active galactic nuclei (AGN). This study represents the first of its kind for an ultra-hard X-ray (14-195keV; Swift/BAT) volume-limited (DL<40 Mpc) sample…

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

The thermal instability of accretion disks is widely used to explain the activity of cataclysmic variables, but its development in protoplanetary disks has been studied in less detail. We present a semi-analytical stationary model for…

Earth and Planetary Astrophysics · Physics 2023-07-31 Ya. N. Pavlyuchenkov , V. V. Akimkin , A. P. Topchieva , E. I. Vorobyov

During their formative stages, giant planets are fed by infalling material sourced from the background circumstellar disk. Due to conservation of angular momentum, the incoming gas and dust collects into a circumplanetary disk that…

Earth and Planetary Astrophysics · Physics 2025-12-10 Aster G. Taylor , Fred C. Adams , Nuria Calvet

Observations of protoplanetary disks suggest that the gas and dust follow significantly different radial distributions. This finding can be theoretically explained by a combination of radial drift and gas drag of intermediate-sized dust…

Solar and Stellar Astrophysics · Physics 2016-01-13 L. Ilsedore Cleeves

We study the influence of the turbulent transport on ice chemistry in protoplanetary disks, focusing on carbon and nitrogen bearing molecules. Chemical rate equations are solved with the diffusion term, mimicking the turbulent mixing in the…

Earth and Planetary Astrophysics · Physics 2015-06-22 Kenji Furuya , Yuri Aikawa
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