Astrophysics & Planetary Sciences Colloquia

Multi-messenger Astrophysics: Probing Compact Objects with Cosmic Particles

The study of compact objects such as black holes and neutron stars is an important component of modern astrophysics. Recent detections of astrophysical neutrinos, gamma-rays, ultrahigh energy cosmic rays, and gravitational waves open up opportunities to study compact objects with multi-messengers. In this talk, we first review the latest progress in Astroparticle Physics, including some surprising puzzles revealed by new observations. We demonstrate that the key to Multi-messenger Astrophysics is to understand and establish the link between the messengers.

The Sun, the stars and Jupiter Aswirl

Fluid dynamics pervades the physics of stellar interiors and planetary atmospheres. Our Sun and Jupiter are at first glance very different from each other, and even more different from the other stars. However, by studying fundamental processes in one system we sometimes learn surprising things about the others. In this talk, I will summarize advances made at CU in studying these objects. I will start with fundamental studies of the fluid dynamics within rotating stratified systems motivated by outstanding problems in Solar convection.

New Insights into Plasma Turbulence

Many plasmas of interest – in astrophysical applications, in space, and in the laboratory – exhibit very large Reynolds numbers, implying that they are invariably found to be in a turbulent state. This pervading turbulence thus becomes a critical element in the understanding of phenomena such as energy dissipation, particle acceleration, magnetic field generation and dynamics, transport properties, etc. Because these plasmas are magnetized, theoretical descriptions of plasma turbulence have to take into account the dynamic interaction between the plasma and the magnetic field.

Using Debris Disks to Trace the Dynamics of Planetary Systems

Debris disks are signposts of mature planetary systems, and millimeter-size dust is an excellent tracer of the gravitational landscape around planets. I will describe observations using the Atacama Large Millimeter/Submillimeter Array (ALMA) that leverage the presence of debris disks to explore the dynamics of planetary systems. For example, we can use the vertical puffiness (or lack thereof) to hunt for otherwise invisible Uranus and Neptune analogs, and in systems with directly imaged companions we can use the chaotic zone extent as a measurement of the dynamical mass of the companion.

Reflections from 50 Years of Teaching Astronomy

I’ve had the opportunity to teach astronomy off and on for 50 years. In this colloquium, I’ll describe and share the most valuable, useful, and surprising lessons I’ve learned. Particular emphasis will be on the results of experiments conducted on large numbers of university students and faculty: What can be better than a clear, well-explained, interesting lecture? Is it true that student mistakes are not random (yes) and how should faculty respond to this? What technology increases learning, and what decreases it?