Astronomy Colloquium

Colloquium meetings are held in the Bryant Space Science Center Building (BRT) in Room 217 from 12:45–1:45 pm every Thursday of the Fall and Spring semesters.

Refreshments will be served after the talk in Room 311

Coordinators: Elizabeth Lada, Anthony Gonzalez, Rafael Guzman, Desika Narayanan


Fall 2017 Schedule

AUGUST 31HOST: Department
Speaker
Title
Welcome Back: Total Solar Eclipse 2017 Recap

SEPTEMBER 21HOST: Elizabeth Lada
Speaker
Andrew Mann,
University of Texas
Title
Observing Planetary Evolution from Formation to Maturity

Abstract

Planets are not born in their final state; before reaching a more mature and stable phase, young planets are significantly altered and reshaped by their environment. The first few hundred million years are thought to be the most formative, but planets in this age range are also the most difficult to identify and characterize. Instead, research has focused on inferring the history of exoplanets through patterns in the population of older systems. I will discuss how this paradigm is shifting, as novel search techniques and new missions have enabled our discovery of Earth- to Neptune-size transiting planets as young as 10 Myr. These discoveries have enabled new constraints on how close-in exoplanets form and migrate, and provided unique insight into how planets lose atmosphere. However, the current sample of young, transiting planets is too small to make conclusions about the bulk properties of their structures and atmospheres. The upcoming TESS mission, however, is expected to discover dozens or hundreds more young planets, including analogues of a young Earth, and planets orbiting bright stars ideal for detailed study. In the long term, JWST and 30m-class telescopes can eventually be used to probe the atmospheres of young, rocky planets, providing direct information on the history precursor of potentially habitable planets.

SEPTEMBER 22HOST: Department
Speaker
Graduate Students
Title
Grad Student Jamboree

SEPTEMBER 28HOST: Stephen Eikenberry
Speaker
Saida Caballero,
Florida Institute of Technology
Title
The Young and the Massive: Stars at the upper end of the IMF

Abstract

The upper mass limit of stars remains an open question in astrophysics. We will discuss observations of the most massive stars (greater than 100 solar masses) in the local universe and how the observations fit in with theoretical predictions. In particular, the Large Magellanic Cloud plays host to numerous very massive stars, making it an ideal template to study the roles that environment, metallicity, and multiplicity play in the formation and evolution of the most massive stars. We will discuss the work that is instrumental in laying the groundwork for interpreting future observations by James Webb of starburst regions in the high redshift universe.

OCTOBER 5HOST: Desika Narayanan
Speaker
Paul Torrey,
Massachusetts Institute of Technology
Title
Probing Galaxy Formation with Modern Cosmological Simulations

Abstract

Cosmological simulations are among the most powerful tools available to probe the non-linear regime of cosmic structure formation. They also provide a clear test-bed for understanding the impact that hydrodynamics and feedback processes have on the evolution of galaxies. I will present an overview of modern galaxy formation simulations that couple a novel moving mesh computational method with explicit baryon feedback prescriptions. This approach results in detailed galaxy formation models that reproduce fundamental observations such as the galaxy stellar mass function, cosmic star formation rate density, and galaxy morphological diversity. In turn, we are able to leverage these simulations to derive physical knowledge on a wide range of science questions, including the importance of supernova and black hole feedback on galaxy growth, the impact of environment on galaxy properties, the origin of diverse morphological types, and much more. I will discuss some of the most interesting insights gained from these simulations as well as ongoing efforts to improve the physical fidelity of our models.

OCTOBER 12HOST: Desika Narayanan
Speaker
Karin Sandstrom,
University of California, San Diego
Title
Interstellar Dust at Low Metallicity

Abstract

Dust plays critical roles in many of the processes occurring in the interstellar medium and dust’s infrared emission serves as a tracer for the ISM and star formation from the nearby universe out to high redshift. While most of our knowledge of dust is built from observations of the local area of the Milky Way, it is clear that dust properties change dramatically in low metallicity conditions which may be prevalent at high redshift and in nearby dwarf galaxies. I will discuss what we know about how dust properties change with metallicity and how this can impact physical processes occurring in the ISM. I will also present new results from studying low-metallicity dust in the Small Magellanic Clouds and other nearby galaxies. Finally, I will describe the exciting prospects for learning more about low metallicity dust with new and upcoming observational facilities like the James Webb Space Telescope.

OCTOBER 19HOST: Stephen Eikenberry
Speaker
Jeremy Darling,
University of Colorado
Title
Real-Time Cosmology

Abstract

Ours is a dynamic universe, so most cosmological observables such as redshift, distance, or flux change over time: given enough time or enough precision, these quantities will be observed to drift. One can compensate for the short careers of astronomers by seeking high precision, but measurements of parts per billion to parts per trillion are required. Nevertheless, "real-time" cosmology is now possible with precise measurement and monitoring of the locations of objects in the sky. In an accelerating universe, cosmological redshifts of objects will drift. In an expanding universe, objects will appear to shrink as they recede, providing a geometrical distance measurement. Large-scale structures of galaxies can be observed to collapse in real time. The baryon acoustic oscillation will converge, primarily due to cosmic expansion. Gravitational waves will cause distant objects to appear to move in the sky. Anisotropy or violation of the Copernican Principle will manifest as cosmic shear. The acceleration of the Sun's orbit causes distant quasars to appear to stream toward the Galactic Center. The motion of the Sun with respect to the Cosmic Microwave Background provides a means to measure the parallax (and thus distance) of galaxies in the local universe. The proper rotation of other galaxies can be observed (the infamous van Maanen effect), also providing a geometric distance. I present the first theoretical predictions of -- and the first application ofobservations to -- many of these phenomena and demonstrate that we can expect to measure most of these effects within the next decade.

OCTOBER 26
Speaker
Amy Mainzer,
JPL/NASA

NOVEMBER 2HOST: Anthony Gonzalez
Speaker
Anja von der Linden,
SUNY Stony Brook

NOVEMBER 9HOST: Joint with Physics
Speaker
Shane Larson,
Northwestern University

NOVEMBER 16HOST: Desika Narayanan
Speaker
Dan Marrone,
University of Arizona

NOVEMBER 30HOST: Jian Ge
Speaker
Eric Lopez,
NASA Goddard Space Flight Center
Title
Understanding Planet Formation by Studying the Evolution of Small Hot Transiting Exoplanets