Category: Seminars

The iPLEX Spring 2017 Guest Speaker Schedule:

Please join us on Fridays from 12 to 1pm in UCLA Geology Building (Room 3-814), followed by lunch 1 to 2pm.

 

Apr 07: Jessie Christiansen (Caltech/JPL) – Taking the Galactic Exoplanet Census

Measuring the occurrence rate of extrasolar planets is one of the most fundamental constraints on our understanding of planets throughout the Galaxy. By studying planet populations across a wide parameter space in stellar age, type, metallicity, and multiplicity, we can inform planet formation, migration and evolution theories. The NASA Kepler mission was a space-based survey for transiting exoplanets, primarily focussed on measuring the occurrence rates of Earth-like planets orbiting Sun-like stars. I will describe our ongoing efforts to catalogue the exoplanets in the Kepler field, including characterizing the survey completeness and reliability, and summarize our progress towards measuring robust occurrence rates. I will also describe the opportunity afforded by the NASA K2 mission, the successor to the Kepler mission, to expand occurrence rate calculations into a wider stellar parameter space.

Apr 14: Joseph O’Rourke (Caltech) – Generating Magnetic Fields in Earth, Venus, and Super-Earth Exoplanets

Earth’s global magnetic field has survived for at least 3.5 billion years, yet Venus lacks a dynamo today. I will explore possible explanations for this dichotomy and discuss related implications for the internal structure and evolution of massive, rocky exoplanets.

Apr 21: Peter Martin (Caltech) – A Young K-Ar Age of Jarosite in the Mojave 2 Sample at Gale Crater, Mars

Abstract TBA

Apr 28: Lucio Mayer (University of Zurich) – Talk Title and Abstract TBA

May 05: Thomas Navarro (UCLA) – Talk Title and Abstract TBA

May 12: Marta Bryan (Caltech) – Talk Title and Abstract TBA

May 19: Geoff Blake (Caltech) – Talk Title and Abstract TBA

May 26: Yoonyoung Kim (Seoul National University) – Talk Title and Abstract TBA

Jun 02: TBA

Jun 09: Chad Trujillo (Northern Arizona University) – Talk Title and Abstract TBA

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.

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.

Danielle Hastings (UCLA): Using relative photometry from the Hubble Space Telescope and 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.

David Jewitt (UCLA): I will present observations suggesting the role of rotational disruption in the solar system.

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

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 approximate 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.

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.

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 Ceres underwent ice-rock fractionation or formed from a different reservoir 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.

Many current theories posit a period of chaotic dynamical alterations throughout the middle and outer Solar System, during which the orbital architecture of the gas and ice giants changed drastically and the remnant planetesimals from planet formation 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.

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.