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Astrophysics Luncheon Seminar

Insights on the Structure and Dynamics of Magnetized Interstellar Filaments
Presented by Gina Panopoulou
California Institute of Technology

Monday, August 13, 2018
12:00 noon in 169-336

Filamentary structures host most of the star forming activity in nearby molecular clouds. Thus, a complete understanding of the onset of star formation relies on studying the formation and evolution of such structures. I will discuss, from an observational perspective, two particularly interesting properties of filaments: their connection to the magnetic field and their apparent "constant" width.

Filament orientations appear to be closely related to the morphology of the magnetic field within dense star-forming clouds. The observed connection suggests that the field is dynamically important in such systems. However, it is unclear at what stage(s) of a cloud's life and at what range of lengthscales the magnetic field plays a critical role in the shaping of cloud material. I will present our investigation of the situation in the poorly studied regime of cloud formation. We have mapped the (plane-of-sky) magnetic field morphology of a nearby translucent molecular cloud, the Polaris Flare, using starlight polarimetry. We combine this map with Herschel observations of dust filaments to infer the importance of the magnetic field relative to other forces in the cloud.

Dust filaments in the Polaris Flare and other nearby clouds are reported to have a "characteristic" width of 0.1 pc, irrespective of their column density. However, a robust theoretical explanation for this characteristic scale has proved elusive. I will highlight discrepancies between this result and other observational evidence. By revisiting the analysis of filament widths, we have found that the origin of the typical width can be traced back to biases in the previously adopted analysis.

JPL Contact: Jorge Pineda (4-3347)

SVCP Astrophysics

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