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2020-09-25 Abstract

Title: From large-scale molecular clouds to filaments and cores: Unveiling the role of the magnetic fields in star formation
 
Speaker:  Dr. Sayantan Auddy (ASIAA)
 
Date: September 25 at 14:30
 
Location: R521, General Building II
 
Abstract: 
The role of the magnetic fields in star formation is an area of active research. However, direct magnetic field measurements, for example, using the Zeeman effect are rarely successful. Thus the alternative is to look for indirect signatures and find a link between the observed structural properties of molecular clouds and the ambient magnetic field strength (or mass-to-flux ratio). In this talk, I will discuss some of our recent studies on the influence of the strong magnetic fields in characterizing the structure of molecular clouds. We run three-dimensional turbulent non-ideal magnetohydrodynamic simulations (with ambipolar diffusion) to see the effect of magnetic fields on the evolution of the column density probability distribution function (PDF). Our results indicate a systematic dependence of the column density PDF of molecular clouds on magnetic field strength and turbulence, with observationally distinguishable outcomes between supercritical (gravity dominated) and subcritical (magnetic field dominated) initial conditions. I will also present a scenario for the formation of oscillatory quasi-equilibrium magnetic ribbons in turbulent subcritical molecular clouds. The synthetic observed relation between apparent width in projection versus observed column density is relatively flat, similar to observations of molecular cloud filaments, and unlike the simple expectation based on a Jeans length argument. Additionally, I will introduce a new “core field structure” (CFS) model to predict the magnetic field strength and magnetic field fluctuation profile of dense cores using gas kinematics.
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