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Large field surveys of NH3, C2S, 13CO and C18O in the L1551 dark cloud have revealed a prolate, pre-protostellar molecular core (L1551-MC) in a relatively quiescent region to the northwest of the well-known IRS 5 source. The kinetic…

Astrophysics · Physics 2009-11-10 J. Swift , Wm. J. Welch , J. Di Francesco

We report our observational results of 870 $\mu$m continuum emission and its linear polarization in the massive star formation site W51 e2/e8. Inferred from the linear polarization maps, the magnetic field in the plane of sky (B$_{\bot}$)…

Solar and Stellar Astrophysics · Physics 2009-07-22 Ya-Wen Tang , Paul T. P. Ho , Patrick M. Koch , Josep M. Girart , Shih-Ping Lai , Ramprasad Rao

We attempt to verify recent claims (made using semi-analytic models) that for the collapse of spherical homogeneous molecular clouds, fragmentation of the self-gravitating disc that subsequently forms can be predicted using the cloud's…

Solar and Stellar Astrophysics · Physics 2015-05-30 Duncan Forgan , Ken Rice

We have developed a modified form of the equations of smoothed particle magnetohydrodynamics which are stable in the presence of very steep density gradients. Using this formalism, we have performed simulations of the collapse of magnetised…

Solar and Stellar Astrophysics · Physics 2018-03-29 Benjamin T. Lewis , Matthew R. Bate , Daniel J. Price

The stellar core formation and high speed jets driven by the formed core are studied by using three-dimensional resistive MHD nested grid simulations. Starting with a Bonnor-Ebert isothermal cloud rotating in a uniform magnetic field, we…

Astrophysics · Physics 2009-11-11 Masahiro N. Machida , Shu-ichiro Inutsuka , Tomoaki Matsumoto

In the standard picture of isolated star formation, dense ``starless'' cores are formed out of magnetic molecular clouds due to ambipolar diffusion. Under the simplest spherical geometry, I demonstrate that ``starless'' cores formed this…

Astrophysics · Physics 2009-10-31 Zhi-Yun Li

We present 350 micron polarization observations of four low-mass cores containing Class 0 protostars: L483, L1157, L1448-IRS2, and Serp-FIR1. This is the second paper in a larger survey aimed at testing magnetically regulated models for…

We report results from twelve simulations of the collapse of a molecular cloud core to form one or more protostars, comprising three field strengths (mass-to-flux ratios, {\mu}, of 5, 10, and 20) and four field geometries (with values of…

Solar and Stellar Astrophysics · Physics 2017-08-28 Benjamin T. Lewis , Matthew R. Bate

We report new 350 micron polarization observations of the thermal dust emission from the cores surrounding the low-mass, Class 0 YSOs L1527, IC348-SMM2 and B335. We have inferred magnetic field directions from these observations, and have…

Filaments are considered to be basic structures and molecular clouds consist of filaments. Filaments are often observed as extending in the direction perpendicular to the interstellar magnetic field. The structure of filaments has been…

Astrophysics of Galaxies · Physics 2015-05-13 Kohji Tomisaka

We perform event-driven molecular dynamics simulations of a system composed by uniaxial hard ellipsoids for different values of the aspect-ratio and packing fraction . We compare the molecular orientational-dependent structure factors…

Soft Condensed Matter · Physics 2012-07-06 Cristiano De Michele , Antonio Scala , Rolf Schilling , Francesco Sciortino

In this paper, we review some of the properties of dense molecular cloud cores. The results presented here rely on three-dimensional numerical simulations of isothermal, magnetized, turbulent, and self-gravitating molecular clouds (MCs) in…

Astrophysics · Physics 2008-08-29 Sami Dib , Roberto Galvan-Madrid , Jongsoo Kim , Enrique Vazquez-Semadeni

We present Submillimeter Array 880 $\mu$m dust polarization observations of six massive dense cores in the DR21 filament. The dust polarization shows complex magnetic field structures in the massive dense cores with sizes of 0.1 pc, in…

Astrophysics of Galaxies · Physics 2017-04-05 Tao-Chung Ching , Shih-Ping Lai , Qizhou Zhang , Josep M. Girart , Keping Qiu , Hauyu B. Liu

Under the assumptions that molecular clouds are nearly spatially and temporally isothermal and that the density peaks (``cores'') within them are formed by turbulent fluctuations, we argue that cores cannot reach a hydrostatic (or…

A local magnetic equilibrium solution is sought around the magnetic axis in order to identify the key parameters defining the magnetic-surface's up-down asymmetry in the core of tokamak plasmas. The asymmetry is found to be determined…

Plasma Physics · Physics 2014-10-08 Paulo Rodrigues , Nuno F. Loureiro , Justin Ball , Felix I. Parra

We formulate the problem of the formation of magnetically supercritical cores in magnetically subcritical parent molecular clouds, and the subsequent collapse of the cores to high densities, past the detachment of ions from magnetic field…

Astrophysics · Physics 2011-02-11 Konstantinos Tassis , Telemachos Ch. Mouschovias

We present the first published maps of magnetic fields in pre-stellar cores, to test theoretical ideas about the way in which the magnetic field geometry affects the star formation process. The observations are JCMT-SCUBA maps of 850 micron…

Astrophysics · Physics 2009-10-31 D. Ward-Thompson , J. M. Kirk , R. M. Crutcher , J. S. Greaves , W. S. Holland , P. Andre

When the gas of a magnetized filamentary cloud obeys a polytropic equation of state, gravitational collapse of the cloud is studied using a simplified model. We concentrate on the radial distribution and restrict ourselves to the purely…

Astrophysics · Physics 2009-11-10 Mohsen Shadmehri

We present a study of the relative orientation between the magnetic field and elongated cloud structures for the $\rho$ Oph A and $\rho$ Oph E regions in L1688 in the Ophiuchus molecular cloud. Combining inferred magnetic field orientation…

We present a large-scale view of the magnetic field in the central 2deg * 2deg region of our Galaxy. The polarization of point sources has been measured in the J, H, and Ks bands using the near-infrared polarimetric camera SIRPOL on the 1.4…