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 talk in Room 311

Coordinator: Elizabeth Lada


Spring 2017 Schedule

JANUARY 12HOST: Desika Narayanan
Speaker
Charley Conroy,
Harvard University
Title
Unraveling Galaxy Formation Histories with Semi-Resolved Stellar Populations

Abstract

The analysis of stellar populations has traditionally been pursued in two limiting cases: spatially-resolved stellar populations in the color-magnitude diagram, and integrated light observations of distant systems. In between these two extremes lies a rich and relatively unexplored realm of observational phenomena. In this talk I will describe our efforts to develop techniques and analyze datasets exploiting the “semi-resolved” stellar population regime, both spatially and temporally. We have used these techniques to unravel the stellar populations of nearby galaxies, which has offered new insights into their formation histories. These new tools will play an important role in maximizing the science returns from next generation ground and space-based facilities.

JANUARY 19
JANUARY 26
FEBRUARY 2HOST: Charlie Telesco
Speaker
Jamie Foster,
University of Florida
Title
Stromatolites: Windows into the Ancient Earth

Abstract

Stromatolites are the oldest known ecosystems on Earth, with fossils that date back more then 3700 million years. These ancient ecosystems once dominated the planet and dramatically changed the Earth’s atmosphere and landscape. In this seminar, Dr. Jamie Foster of the University of Florida will talk about the formation of these ancient ecosystems and how the study of modern stromatolites, with state-of-the-art molecular biology tools, can help inform us about how the microbial world adapts to a continuously changing environment.

FEBRUARY 9HOST: Charlie Telesco
Speaker
Marcia Rieke,
University of Arizona
Title
NIRCam for JWST: Your Next Near–Infrared Camera in Space

Abstract

The combination of NIRCam and The James Webb Space Telescope will provide astronomers with another huge leap in sensitivity and spatial resolution. NIRCam's characteristics, operating modes, and performance predictions will be reviewed both in the context of deep field extragalactic surveys and in the context of exoplanet observations. The design drivers for JWST and NIRCam will be examined and how these performance requirements have driven the NIRCam design will be presented. Sample observing programs in the guise of the NIRCam Instrument Team GTO program will also be presented.

FEBRUARY 16HOST: Robert Wilson
Speaker
Ed Sion,
Villanova University
Title
Recurrent Novae as Progenitors of Type Ia Supernovae

FEBRUARY 23HOST: Elizabeth Lada
Speaker
Uma Gorti,
SETI
Title
The Evolution of Gas and Dust in Protoplanetary Disk

Abstract

Protoplanetary disks, as the name implies, form planetary systems within their short lifetimes of a few million years. Understanding how the disk material evolves in time and space is central to our understanding of planetary system formation, with the physical and chemical conditions in the protoplanetary disk affecting not only formation processes, but also planetary compositions and dynamical evolution. In this talk, I will discuss disk evolution mainly from a theoretical perspective. I will describe recent models that consider photoevaporation, or the driving of thermal winds due to stellar heating, as the chief agent of disk dispersal. I will also discuss observational constraints on some of the key physical processes, including gas and dust diagnostics from optical to sub-millimeter wavelengths.

MARCH 2HOST: Elizabeth Lada
Speaker
Sean Andrews,
CFA
Title
Observing the Evolution of Solids in Protoplanetary Disks

Abstract

The canonical model for the formation of terrestrial planets and giant planet cores relies on an early and very efficient phase of planetesimal growth in a gas-rich circumstellar disk. But, as theorists have known for decades now, there are some formidable obstacles to meeting that requirement. Many of these problems, and potentially their solutions, are associated with the growth and migration of "pebbles" (mm/cm-sized particles) in the first few million years of a disk's lifetime. That is fortuitous, since the continuum emission from these particles in nearby disks can be readily detected and resolved with long-baseline radio interferometers (e.g., ALMA, VLA). In this talk, I will describe what we are learning about the evolution of solids from such data, including: (1) the signatures of particle growth and migration; and (2) the mounting evidence that small-scale substructures in the (gas) disk play fundamental - and perhaps mandatory - roles in the planet formation process.

MARCH 16HOST: Desika Narayanan
Speaker
Peter Behroozi,
University of California, Berkeley
Title
The Connection between Galaxy Growth and Dark Matter Halo Assembly from z=0–10

Abstract

We present a short review of the connection between galaxies and dark matter halos, followed by a new method to flexibly and self-consistently infer individual galaxies' star formation rates as a function of their host halos' potential well depths, assembly histories, and redshifts. The method is able to match galaxies' observed stellar mass functions, star formation rates (specific and cosmic), quenched fractions, UV luminosity functions, autocorrelation functions and lensing shear (including for quenched and star-forming subsamples), and quenching dependence on environment; each observable is reproduced over the full redshift range available, up to 0<z<10. We discuss physical implications for galaxy quenching, the connection between halo and galaxy assembly, revised stellar mass-halo mass relations, and predictions for higher-redshift galaxy correlation functions and weak lensing signals.

MARCH 23HOST: Anthony Gonzalez
Speaker
Lou Strolger,
STScI
MARCH 30HOST: Anthony Gonzalez
Speaker
Allison Kirkpatrick,
Yale University
Title
Dusty Star Forming Galaxies in the Distant Universe

APRIL 6HOST: Anthony Gonzalez
Speaker
Greg Dobler,
NYU
APRIL 13HOST: Jian Ge
Speaker
Xiaohui Fan,
University of Arizona
Title
The Most Luminous Quasars in the Early Universe