arXiv subjects

Ellen Zweibel

Publications and source records attributed to Ellen Zweibel.

24 records · Page 2Linked to original sources

arXiv2010

An Experimental Plasma Dynamo Program for Investigations of Fundamental Processes in Heliophysics

Plasma experiments in laboratory settings offer unique opportunities to address fundamental aspects of the solar dynamo and magnetism in the solar atmosphere. We argue here that ground-based laboratory experiments have direct connections to NASA based missions and NSF programs, and that a small investment in laboratory heliophysics may have a high payoff. We advocate for broad involvement in community-scale plasma experiments.

astro-ph.SR↗

arXiv2009

Plasma Physics Processes of the Interstellar Medium

We discuss the outstanding issues of the interstellar medium which will depend on the application of knowledge from plasma physics. We particularly advocate attention to recent developments in experimental plasma physics, and urge that the astronomical community consider support of these experiments in the next decade.

astro-ph.GA↗

arXiv2009

Plasma Astrophysics Problems in Star and Planet Formation

The major questions relevant to star and planet formation are: What controls the rate, efficiency, spatial clustering, multiplicity, and initial mass function of star formation, now and in the past? What are the major feedback mechanisms through which star formation affects its environment? What controls the formation and orbital parameters of planets, especially terrestrial planets? These questions cannot be fully addressed without understanding key magnetohydrodynamics (MHD) and plasma physics processes. Although some of these basic problems have long been considered intractable, attacking them through a combination of laboratory experiment, theory, and numerical simulation is now feasible, and would be fruitful. Achieving a better understanding of these processes is critical to interpreting observations, and will form an important component of astrophysical models. These models in turn will serve as inputs to other areas of astrophysics, e.g. cosmology and galaxy formation.

astro-ph.EP↗

arXiv2007

Magnetic Fields in Irregular Galaxies

Magnetic fields are an important component of the interstellar medium, especially in low-mass galaxies like irregulars where the magnetic pressure may be significant. However, few irregular galaxies have observed magnetic field structures. Using the VLA, the GBT, and the ATCA, we have observed several irregular galaxies in the radio continuum to determine their magnetic field structures. Here we report on our results for the galaxies NGC 4214 and NGC 1569.

astro-ph↗

arXiv2004

Dust heating by the interstellar radiation field in models of turbulent molecular clouds

We have calculated the radiation field, dust grain temperatures, and far infrared emissivity of numerical models of turbulent molecular clouds. When compared to a uniform cloud of the same mean optical depth, most of the volume inside the turbulent cloud is brighter, but most of the mass is darker. There is little mean attenuation from center to edge, and clumping causes the radiation field to be somewhat bluer. There is also a large dispersion, typically by a few orders of magnitude, of all quantities relative to their means. However, despite the scatter, the 850 micron emission maps are well correlated with surface density. The fraction of mass as a function of intensity can be reproduced by a simple hierarchical model of density structure.

astro-ph↗

arXiv2003

Turbulence in the Star-forming Interstellar Medium: Steps toward Constraining Theories with Observations

Increasingly sophisticated observational tools and techniques are now being developed for probing the nature of interstellar turbulence. At the same time, theoretical advances in understanding the nature of turbulence and its effects on the structure of the ISM and on star formation are occurring at a rapid pace, aided in part by numerical simulations. These increased capabilities on both fronts open new opportunities for strengthening the links between observation and theory,and for meaningful comparisons between the two.

astro-ph↗