Geophysics and Tectonics Seminar - winter-2017

Jan. 20, 2017
noon - 1 p.m.
Geology 3814

Presented By:

• Margaret Pan - MIT

Eccentric rings and disks

I’ll describe two observationally-motivated projects on eccentric systems of colliding particles. First, I’ll discuss a derivation for the mass of the rings orbiting the minor planet Chariklo, and some implications for how those rings formed; second, I’ll discuss azimuthal brightness variations in eccentric debris disks in the context of the very well observed Fomalhaut disk.

Jan. 27, 2017
noon - 1 p.m.
Geology 3814

Presented By:

• Quan-Zhi Ye - Caltech

Probing The Comet-Asteroid Continuum

The era of modern astronomy is unfortunately not long enough to cover the typical lifetime of comets. However, comets produce dust which is potentially detectable as meteor activity at the Earth. Here I discuss the effort to understand cometary aging by examining different parts of the evolution spectrum of Jupiter-family comets (JFCs) by combining telescopic and meteor observations.

Feb. 3, 2017
noon - 1 p.m.
Geology 3814

Presented By:

• Ian Wong - Caltech

Middle and Outer Solar System Bodies As Probes of Solar System Evolution

Many current theories posit a period of dynamical chaos throughout the middle and outer Solar System, during which the orbital architecture of the gas and ice giants changed drastically and the remnant planetesimals were scattered. Using photometry, spectroscopy, and magnitude distribution analysis to study the present-day minor bodies that occupy this region namely, Jupiter Trojans, Hilda asteroids, Kuiper Belt objects and Centaurs we can compare the properties of the various populations and begin to evaluate our understanding of Solar System evolution.

Feb. 10, 2017
noon - 1 p.m.
Geology 3814

Presented By:

• Thomas Prettyman - PSI

Evidence for aqueous alteration and ice-rock fractionation on (1) Ceres

Analyses of data acquired by the NASA Dawn mission show that the surface of large asteroid Ceres is rich in hydrogen in the form of phyllosilicates, water ice, and perhaps organic matter. Differences between Ceres` surface elemental composition and that of the primitive CI chondrites suggest that Ceres underwent ice-rock fractionation or formed from a reservoir other than the CI parent body. Composition data acquired by Dawn provide further constraints on Ceres’ origins, hydrothermal evolution, and present state, placing Ceres in context with other icy, solar system bodies.

Feb. 17, 2017
noon - 1 p.m.
Geology 3814

Presented By:

• Dan Cziczo - MIT

Ice Nucleation: From The Earth To Mars And Beyond

Ice nucleation in the Earth’s atmosphere is known to be an important factor in climate, chemistry, and precipitation. By mimicking that planet’s atmosphere, we can leverage tools for terrestrial studies of ice clouds to understand the Martian water and carbon cycles. Recent observations show clouds to be present around exoplanets as well. Although measurements are much more uncertain, these technologies can help elucidate the atmospheres of these distant planets.

Feb. 24, 2017
noon - 1 p.m.
Geology 3814

Presented By:

• David Jewitt - UCLA

Rotationally Disrupting Bodies

I will present observations of a disrupting asteroid and a disrupting comet nucleus, and argue that the mechanism in both cases is rotational disruption of a nearly strengthless (~100 M/m^2) aggregate.

Feb. 24, 2017
noon - 1 p.m.
Geology 3814

Presented By:

• Danielle Hastings - UCLA

The Rotation Period of Hi’iaka, Haumea’s Largest Satellite

Using relative photometry from the Hubble Space Telescopeand Magellan, we have found that Hi’iaka, the largest satellite of the dwarf planet Haumea, has a rotation period of ~9.8 hours. This surprisingly short period, ~120 times faster than its orbital period, creates new questions about the formation of the Haumea system and possible tidal evolution.

March 3, 2017
noon - 1 p.m.
Geology 3814

Presented By:

• Eric Mamajek - JPL

A Transiting Extrasolar Ring System

I’ll discuss the discovery and characterization of the “J1407” (V1400 Cen) system and its eclipsing complex ring system. J1407 is an otherwise unremarkable ~15 Myr-old pre-main sequence solar-mass star lacking infrared excess. The disk/ring system transiting J1407 is tenths of an AU in size with mass similar to that of the Earth, and the best models thus far require dozens of rings. The system is intermediate in size and mass between Saturn’s rings and circumstellar disks, and may represent the first example of a protoexosatellite disk and indirect evidence of exomoon formation.

March 10, 2017
noon - 1 p.m.
Geology 3814

Presented By:

• Roger Fu - Harvard University

Meteorite Paleomagnetism

Magnetic fields permeated the partially ionized gas of the solar nebula and may have also been generated by metallic core dynamos in early-forming planetesimals. I will talk about paleomagnetic experiments on meteorites that yield information on the evolution of the protoplanetary disk and the accretion of planetary bodies.

March 17, 2017
noon - 1 p.m.
Geology 3814

Presented By:

• Zhaohuan Zhu - UNLV

Young Planets in Protoplanetary Disks: Theory Confronts Observations

Recently commissioned telescopes and instruments (e.g., Subaru, GPI, VLA, ALMA, EVLA) are now finally able to resolve the protoplanetary disk down to the AU scale, and a rich variety of disk features have been revealed. In this talk, I will discuss how these observations can constrain protoplanetary disk dynamics and planet formation theory.