Physics and Astronomy Colloquium

All future

Thursday, November 29th 2018
3:35 pm:
Speaker: Marco Velli, UCLA
Subject: Parker Solar Probe: Understanding Coronal heating and Solar Wind acceleration
Refreshments in atrium after the Colloquium.

The magnetic field is fundamental to solar activity and shapes the inter-planetary environment, as shown by the full three dimensional monitoring of the heliosphere provided by measurements from many past and present interplanetary and remote sensing spacecraft. Magnetic fields are also the source for coronal heating and the very existence of the solar wind; produced by the sun’s dynamo and emerging into the corona, magnetic fields become a conduit for waves, act to store energy, and then propel plasma into the Heliosphere in the form of Coronal Mass Ejections (CMEs). Magnetic fields are also at the heart of the generation and acceleration of Solar Energetic Particle (SEPs) that modify the space weather environment of the Earth and other planets.

Parker Solar Probe (PSP) was launched in August 2018 to carry out the first in situ exploration of the outer solar corona and inner Heliosphere. Direct measurements of the plasma in the closest atmosphere of our star should lead to a new understanding of the questions of coronal heating, solar wind acceleration, and the generation, acceleration and propagation of SEPs.

In this lecture I will start from an introduction to our present knowledge of the magnetized solar corona and wind before describing the PSP scientific objectives, orbit, and instrument suites, and perhapse showing a glimpse from initial data. Emphasis will be on how PSP will confirm or falsify present models as well as the potential new discoveries stemming from the first exploration of the space inside the orbit of Mercury. I will also discuss how synergies with Solar Orbiter might lead us to accurately understand the state of the solar wind all the way from the corona into interplanetary space, a stepping stone
for understanding the dynamics of active magnetized plasmas throughout the universe.

Faculty Host: Robert Lysak

Thursday, December 6th 2018
3:35 pm:
Speaker: Stacy McGaugh, Case Western
Subject: Dynamical Regularities in Galaxies and their Implications for Dark Matter
Refreshments in atrium after the Colloquium.

The flat rotation curves of galaxies were a surprising observation that helped establish the dark matter paradigm. Flat rotation curves are only the first of a series of striking regularities in the dynamics of galaxies. The amplitude of the flat rotation speed is not random; it correlates strongly with the mass observed in stars and gas (the baryonic Tully-Fisher relation). At the centers of galaxies, the dynamical surface density correlates with the observed surface brightness of stars (the central density relation). At all observed radii, the observed centripetal acceleration correlates with the acceleration predicted by the observed distribution of baryons (the radial acceleration relation). These empirical relations inform our thinking about the missing mass problem in ways that were not available when the current paradigm was established.

Faculty Host: J. Woods Halley

Thursday, January 31st 2019
3:35 pm:
Speaker: Roger Steuwer, U of Minnesota
Subject: From tFrom the Old to the New World of Nuclear Physics, 1919-1939he Old to the New World of Nuclear Physics, 1919-1939
Refreshments in atrium after the Colloquium.
Faculty Host: Michel Janssen

Thursday, May 2nd 2019
3:35 pm:
Speaker: Jack Harris (Yale University)
Subject: TBD
Refreshments in atrium after the Colloquium.
Faculty Host: Paul Crowell

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