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Magnetic fields (B-fields) play an important role in molecular cloud fragmentation and star formation, but are very difficult to detect. The temporal correlation between the field strength (B) and gas density (n) of an isolated cloud has…

Astrophysics of Galaxies · Physics 2023-04-26 Zhuo Cao , Hua-bai Li

We (Li et al. 2009; Paper-I) compared the magnetic field directions inferred from polarimetry data obtained from 100-pc scale inter-cloud media (ICM) and from sub-pc scale molecular cloud cores. The highly correlated result led us to…

Astrophysics of Galaxies · Physics 2019-08-10 Y. Zhang , Z. Guo , H. H. Wang , H-b Li

Observations of magnetic field strengths imply that molecular cloud fragments are individually close to being in a magnetically critical state, even though both magnetic field and column density measurements range over two orders of…

Astrophysics · Physics 2007-05-23 Shantanu Basu

One of the key problems in star formation research is to determine the role of magnetic fields. Starting from the atomic inter-cloud medium (ICM) which has density nH ~ 1 per cubic cm, gas must accumulate from a volume several hundred pc…

Astrophysics of Galaxies · Physics 2015-05-13 Hua-bai Li , C. Darren Dowell , Alyssa Goodman , Roger Hildebrand , Giles Novak

The orientations of filamentary molecular clouds in the Gould Belt and their local ICM (inter-cloud media) magnetic fields are studied using near-infrared dust extinction maps and optical stellar polarimetry data. These filamentary clouds…

Astrophysics of Galaxies · Physics 2015-06-17 Hua-bai Li , Min Fang , Thomas Henning , Jouni Kainulainen

The characterization of magnetic fields within molecular clouds is fundamental to understanding star formation processes. Accurately gauging the three-dimensional structure of these fields presents a challenge, as observational techniques…

Astrophysics of Galaxies · Physics 2024-11-18 Brandon Shane , Blakesley Burkhart , Laura Fissel , Susan E. Clark , Philip Mocz , Michael M. Foley

We have carried out an extensive survey of magnetic field strengths toward dark cloud cores in order to test models of star formation: ambipolar-diffusion driven or turbulence driven. The survey involved $\sim500$ hours of observing with…

Astrophysics · Physics 2009-11-13 Thomas H. Troland , Richard M. Crutcher

Magnetic fields of molecular clouds in the Central Molecular Zone (CMZ) have been relatively underobserved at sub-parsec resolution. Here we report JCMT/POL2 observations of polarized dust emission in the CMZ, which reveal magnetic field…

(Abridged) We present a series of decaying turbulence simulations that represent a cluster-forming clump within a molecular cloud, investigating the role of magnetic fields on the formation of potential star-forming cores. We present an…

Astrophysics · Physics 2007-11-07 David A. Tilley , Ralph E. Pudritz

We revisit the relation between magnetic-field strength ($B$) and gas density ($\rho$) for contracting interstellar clouds and fragments (or, cores), which is central in observationally determining the dynamical importance of magnetic…

Astrophysics of Galaxies · Physics 2015-05-22 A. Tritsis , G. V. Panopoulou , T. Ch. Mouschovias , K. Tassis , V. Pavlidou

We present the results of an extensive Arecibo observational survey of magnetic field strengths in the inter-core regions of molecular clouds to determine their role in the evolution and collapse of molecular clouds as a whole. Sensitive 18…

Astrophysics of Galaxies · Physics 2019-10-16 K. L. Thompson , T. H. Troland , C. Heiles

During the star formation process, the interplay between gravity, turbulence, and B-fields is significant, with B-fields apparently serving a regulatory function. However, the extent to which B-fields are decisive relative to turbulence and…

Star formation is primarily controlled by the interplay between gravity, turbulence, and magnetic fields. However, the turbulence and magnetic fields in molecular clouds near the Galactic Center may differ substantially from spiral-arm…

The magnetic field strength in molecular clouds is a fundamental quantity for theories of star formation. It is estimated by Zeeman splitting measurements in a few dense molecular cores, but its volume--averaged value within large molecular…

Astrophysics · Physics 2009-11-10 Paolo Padoan , Raul Jimenez , Mika Juvela , Aake Nordlund

Recent measurements of the Zeeman effect in dark-cloud cores provide important tests for theories of cloud dynamics and prestellar core formation. In this Letter we report results of simulated Zeeman measurements, based on radiative…

Astrophysics of Galaxies · Physics 2016-08-14 Tuomas Lunttila , Paolo Padoan , Mika Juvela , Åke Nordlund

We perform ideal MHD high resolution AMR simulations with driven turbulence and self-gravity and find that long filamentary molecular clouds are formed at the converging locations of large-scale turbulence flows and the filaments are…

Astrophysics of Galaxies · Physics 2019-04-10 Pak Shing Li , Richard I. Klein

(abridged) Together with gravity, turbulence, and stellar feedback, magnetic fields (B-fields) are thought to play a critical role in the evolution of molecular clouds and star formation processes. We aim to map the morphology and measure…

The magnetic field of molecular clouds (MCs) plays an important role in the process of star formation: it determins the statistical properties of supersonic turbulence that controls the fragmentation of MCs, controls the angular momentum…

Astrophysics of Galaxies · Physics 2017-12-12 Paolo Padoan

This review summarizes the argument for molecular clouds being dominated by turbulence, most likely super-Alfvenic turbulence. Five lines of observational evidence are given: molecular linewidths and line shapes, nonequilibrium chemical…

Astrophysics · Physics 2007-05-23 Mordecai-Mark Mac Low

The question whether magnetic fields play an important role in the processes of molecular cloud and star formation has been debated for decades. Recent observations have revealed a simple picture that may help illuminate these questions:…

Astrophysics of Galaxies · Physics 2015-06-19 Hua-bai Li , Alyssa Goodman , T. K. Sridharan , Martin Houde , Zhi-Yun Li , Giles Novak , Kwok Sun Tang
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