中文
相关论文

相关论文: On the efficiency of grain alignment in dark cloud…

200 篇论文

We study infrared emission of 17 isolated, diffuse clouds with masses of order solar masses, to test the hypothesis that grain property variations cause the apparently low gas-to-dust ratios that have been measured in those clouds. Maps of…

星系天体物理 · 物理学 2018-08-13 William T. Reach , Jean-Philippe Bernard , Thomas Jarrett , Carl Heiles

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.…

天体物理学 · 物理学 2015-06-24 A. Lazarian

Polarization at millimeter wavelengths provides a powerful diagnostic of dust grain properties in protoplanetary disks. Standard models based on solid spherical grains often struggle to reproduce the observed polarization fractions and…

Atacama Large Millimeter/Submillimeter Array (ALMA) has revolutionized the field of dust polarization in protoplanetary disks across multiple wavelengths. Previous observations and empirical modeling suggested multiple mechanisms of dust…

太阳与恒星天体物理 · 物理学 2024-07-30 Nguyen Tat Thang , Pham Ngoc Diep , Thiem Hoang , Le Ngoc Tram , Nguyen Bich Ngoc , Nguyen Thi Phuong , Bao Truong

Aligned non-spherical dust particles polarize starlight passing through the dust cloud. They also emit polarized far infrared and sub-mm radiation. Substantial progress in understanding of grain alignment theory makes the interpretation of…

天体物理学 · 物理学 2007-05-23 A. Lazarian

We compiled the polarimetric data for a sample of lines of sight with known abundances of Mg, Si, and Fe. We correlated the degree of interstellar polarization $P$ and polarization efficiency (the ratio of $P$ to the colour excess $E(B-V)$…

星系天体物理 · 物理学 2015-06-04 N. V. Voshchinnikov , Th. Henning , M. S. Prokopjeva , H. K. Das

Recent observation of linear optical polarization from brown dwarfs confirms the dust hypothesis in the atmospheres of brown dwarfs with effective temperature higher than 1400 K. The observed polarization could arise due to dust scattering…

天体物理学 · 物理学 2009-11-07 Sujan Sengupta

We investigate the efficiency of interstellar polarization $p_\lambda/A_\lambda$ where $p_\lambda$ is the fractional linear polarization and $A_\lambda$ is extinction, in 16 lines of sight as a function of wavelength $\lambda$. We have used…

星系天体物理 · 物理学 2015-05-27 Masafumi Matsumura , Youko Kameura , Koji S. Kawabata , Hiroshi Akitaya , Mizuki Isogai , Munezo Seki

We present 450 {\mu}m polarimetric observations of the M17 molecular cloud obtained with the SHARP polarimeter at the Caltech Submillimeter Observatory. Across the observed region, the magnetic field orientation is consistent with previous…

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…

星系天体物理 · 物理学 2022-04-06 Thiem Hoang

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…

太阳与恒星天体物理 · 物理学 2009-01-21 Jungyeon Cho , A. Lazarian

We present ISO-LWS measurements of the main gas cooling lines, C+ 158 mum and O 63 mum towards a moderate opacity molecular cloud (Av=3), L1721, illuminated by the B2 star nu Sco (X = 5-10). These data are combined with an extinction map…

天体物理学 · 物理学 2016-08-30 E. Habart , L. Verstraete , F. Boulanger , G. Pineau des Forets , F. Le Peintre , J. P. Bernard

We examine two positions, ON1 and ON2, within the Ophiuchus cloud LDN 1688 using observations made with the ISOPHOT instrument aboard the ISO satellite. The data include mid-IR spectra (~6-12{\mu}m) and several photometric bands up to…

星系天体物理 · 物理学 2015-06-11 M. G. Rawlings , M. Juvela , K. Lehtinen , K. Mattila , D. Lemke

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…

天体物理学 · 物理学 2010-10-27 W. G. Roberge , A. Lazarian

Dust polarisation observations at optical wavelengths help understand the dust grain properties and trace the plane-of-the-sky component of the magnetic field. In this study, we make use of published optical polarisation data acquired with…

星系天体物理 · 物理学 2024-04-02 N. Bijas , Chakali Eswaraiah , Panigrahy Sandhyarani , Jessy Jose , Maheswar Gopinathan

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…

天体物理学 · 物理学 2008-11-07 A. Lazarian

Located in the Large Magellanic cloud and mostly irradiated by a massive-star cluster R$\,$136, 30 Doradus is an ideal target to test the leading theory of the grain alignment and rotational disruption by RAdiative Torques (RATs). Here, we…

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…

星系天体物理 · 物理学 2021-06-02 Joonas Herranen , A. Lazarian , Thiem Hoang

Optical and infrared continuum polarization from the interstellar medium is known to generally be due to irregular dust grains aligned with the magnetic field. This provides an important tool to probe the geometry and strength of those…

星系天体物理 · 物理学 2019-03-20 Ilija Medan , B-G Andersson

Polarization arising from aligned dust grains presents a unique opportunity to study magnetic fields in the diffuse interstellar medium and molecular clouds. Polarization from circumstellar regions, accretion disks and comet atmospheres can…

星系天体物理 · 物理学 2016-06-21 A. Lazarian , B-G Andersson , Thiem Hoang