2002-2003 Colloquium Series
NAU Physical Sciences (Bldg 19, Rm 218), Thursday, 23 January 2003, 6:00 PM
(Pizza/Soda at 5:30 PM, $2.00 contribution requested for food)
ON THE RAGGED EDGE
Stephen C. Tegler , NAU.
Abstract
Between its discovery in 1930, and 1992, Pluto became known as the oddball planet - it is neither small and rocky like the four inner terrestrial planets nor large and hydrogen-rich like the four outer gas giants - Pluto is tiny (diameter 2,400 km) and ice-rich. Starting in 1992, the discovery of ~ 500 icy objects at and beyond the orbit of Neptune has made it possible for us to understand the reason for Pluto's apparent odd nature - it is the largest and brightest known member of an ancient reservoir of icy objects known as the Kuiper belt. It appears the present day belt contains billions of objects ~ 1 km in diameter, hundreds of thousands of objects ~ 100 km in diameter, perhaps ~ 10 objects as large as Pluto, and optimistically, an undiscovered Mars-sized object. Although the total mass in the belt today is about a few tenths of an Earth mass, accretion calculations suggest the primordial belt contained 10 to 30 Earth masses in order to explain the growth of Pluto and its satellite Charon in the 100 million years before the onset of the disruptive influence of Neptune. Once Neptune reached a fraction of its current mass, erosional collisions and resonances sculpted the belt into its present day mass and structure. The Kuiper belt allows us to study a preserved case of interrupted planet formation in the outer Solar System.
In 1995, we began an important, practical and "doable" first step in the exploration of this new region of the Solar System, a survey of the optical magnitudes and colors of known Kuiper belt objects (KBOs) using ground-based telescopes and charge coupled device (CCD) cameras. As a result of over 100 nights on the Vatican Advanced Technology 1.8-m telescope, the University of Arizona 2.3-m telescope, and the Keck I and II 10-m telescopes, we have discovered a number of unexpected KBO properties that we describe here.
In the years ahead, we hope to use the Large Binocular Telescope
and its nulling interferometry capability to look for some of the
same unexpected properties in pre-planetary disks around T-Tauri
stars. By comparing the properties we see in the outer regions of
our Solar System with the properties of disks around T-Tauri stars,
we expect to gain a greater understanding of the formation and
evolution of planetary systems.
Dr. Tegler received his B.S. in Physics in 1984 from the State University of New York at Stony Brook, and his Ph.D. in Physics in 1989 from Arizona State University. He was at post-doctoral fellow at the University of Florida and then at the University of Notre Dame and came to NAU in 1995, where he is currently an Associate Professor.
Dr. Tegler's research interests include Kuiper Belt objects, comets, optical and infrared imaging and spectroscopy. He maintains an active observing program at the 10m Keck telescopes on Mauna Kea, and the telescopes of Steward Observatory on Kitt Peak and Mt. Graham.
Sponsored by the Northern Arizona Astronomy Association