The Early History of Protostellar Disks, Outflows, and Binary Stars (Duffin & Pudritz 2009, ApJL)
The ideal MHD outflow: evolution and structure
This movie shows the time evolution of the perfectly coupled outflow over a period of 57 years after onset. The positive z-axis is given by the blue arrow. See Figures 1c and d of Duffin & Pudritz 2009 for definition of contours. During the movie, contours are linearly increased to maximal values to reveal the magnetic field lines. As this is done, the structure of the outflow is revealed, including the central region where velocities reach v > 5 km s^(-1).
Structure in the collapse: hydrodynamic
This movie shows the continuous zoom-out from the central region of the hydrodynamic collapse (moderate rotation) to the largest scales (starting from Figure 1a). The dark blue temperature contour represents T = 85 K. Density contours are 1e-12 (black), 1e-13 (gray), 1e-14 (yellow), 1e-15 (turquoise), 1e-16 (red) and 1e-17 g cm^(-3) (dark gray). The positive z-axis is given by the blue arrow.
Structure in the collapse: ambipolar diffusion
This movie shows the continuous zoom-out from the central region of the ambipolar diffusion collapse (moderate rotation) to the largest scales (starting from Figure 1b). Contours are defined above. The blue lines represent the magnetic field and the positive z-axis is given by the blue arrow.
Structure in the collapse: ideal MHD
This movie shows the continuous zoom-out from the central region of the perfectly coupled collapse (moderate rotation) to the largest scales (starting from Figure 1c). Contours are defined above. The blue lines represent the magnetic field and the positive z-axis is given by the blue arrow.
Simulating hydromagnetic processes in star formation: introducing ambipolar diffusion into an adaptive mesh refinement code (Duffin & Pudritz 2008, MNRAS)
Quasi-static collapse
This movie shows the quasi-static collapse of a uniform sphere undergoing ambipolar diffusion. It initially has so much magnetic flux that it is prevented from collapsing due to gravity. However, over time, the mass-to-flux gradually turns over and the freefall collapse takes place. The timescale from thin disk formation to free-fall collapse is about 10 Myr. This was examined in detail in by Fiedler and Mouschovias 1993 (ApJ, 415, 680) and serves as a test of the ambipolar diffusion applied to the FLASH code.
C-shocks
Starting with discontinuous initial conditions in hydrodynamic quantities (a shock), a fluid undergoing ambipolar diffusion will quickly form a smooth transition (a C-shock). These types of shocks represent some of the few analytical tests of a numerical ambipolar diffusion implementation. Quantities are in dimensionless units.
coolstuff
Tilted disk
This tilted disk is a snippet from a new paper we're preparing on early protostellar disk formation. In this Bonnor-Ebert sphere collapse, the magnetic field and axis of rotation were misaligned by 15 degrees, leading to a somewhat skewed disk. Grey contours are density, blue contours are temperature and red contours are outward velocity from the protostellar outflow. Yellow lines represent magnetic field lines.
latest news
12 October 2009
New astroph paper is out! Check it out
here.
19 October 2009
New website! Some actual structure!
key words
This tilted disk is a snippet from a new paper we're preparing on early protostellar disk formation. In this Bonnor-Ebert sphere collapse, the magnetic field and axis of rotation were misaligned by 15 degrees, leading to a somewhat skewed disk. Grey contours are density, blue contours are temperature and red contours are outward velocity from the protostellar outflow. Yellow lines represent magnetic field lines.
New astroph paper is out! Check it out here.
New website! Some actual structure!