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Seminars

Chad Trujillo (Northern Arizona University)

June 09, 2017: Planet X to be Discovered This Fall? Observational and Dynamical Constraints

Posted on Mar 31, 2017 in Seminars

Talk Title: Planet X to be Discovered This Fall? Observational and Dynamical Constraints Abstract: An undiscovered ~10 Earth mass planet in our solar system has been hypothesized to explain the orbital characteristics of about a dozen of the most distant Kuiper Belt Objects (KBOs) and Inner Oort Cloud Objects (IOCs). I’ll present the observational evidence for the planet and explain why the evidence is unlikely to be due to observational bias. I’ve used the known KBOs and IOCs as an input for over two thousand dynamical simulations run on the Northern Arizona University High...

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June 02, 2017: Snow Lines in Gas Rich Protoplanetary Disks and the Delivery of Volatiles to Planetary Surfaces

Posted on Mar 31, 2017 in Seminars

Talk Title: Snow Lines in Gas Rich Protoplanetary Disks and the Delivery of Volatiles to Planetary Surfaces Abstract: Compared to the Sun and to the gas+dust composition of the interstellar medium from which the solar system formed, the Carbon and Nitrogen content of the bulk silicate Earth (mantle+hydrosphere+atmosphere) is reduced by several orders of magnitude, relative to Silicon. Evidence from primitive bodies as a function of distance from the Sun suggests that at least part of this depletion must occur early in the process of planetesimal assembly. With pioneering infrared and (sub)mm...

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May 26, 2017: P/2010 A2: Impact Shattering on an Asteroid

Posted on Mar 31, 2017 in Seminars

Talk Title: P/2010 A2: Impact Shattering on an Asteroid Abstract: I present a new dust modeling analysis on active asteroid P/2010 A2, which was successful to reproduce the morphological evolution of the dust cloud over seven years. Interestingly, no object has been detected at the dust ejection point of this model in any observations. This result suggests that the precursor asteroid was shattered by an impact, leaving only the debris cloud.

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May 12, 2017: Lurking in the Shadows: Long Period Gas Giant Planets as Tracers of Planet Formation

Posted on Mar 31, 2017 in Seminars

Talk Title: Lurking in the Shadows:  Long Period Gas Giant Planets as Tracers of Planet Formation Abstract: Over the past decade surveys using a variety of techniques have uncovered a diverse array of exoplanet systems.  Many of these new systems are difficult to explain within the framework of standard planet formation theories, and have forced theorists and observers alike to re-evaluate their narratives for planet formation and migration.  For example, direct imaging surveys have discovered a growing population of extremely young, planetary-mass companions at separations of > 100 AU,...

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May 05, 2017: Understanding Mars and Venus with a Global Climate Model

Posted on Mar 31, 2017 in Seminars

Talk Title: Understanding Mars and Venus with a Global Climate Model Abstract: A Global Climate Model (GCM) is a convenient and powerful tool for studying any planetary atmosphere. I will give three examples of its application for Mars and Venus. First, I will explain how the modeling of water ice clouds unravels the water cycle on Mars, today and in its recent past. Then, I will present techniques to reconcile a GCM with observations, in particular inside Martian dust storms. Finally, I will tackle the modeling of mysterious gigantic gravity waves recently seen on...

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April 28, 2017: Challenges in computational planet formation; from disk instability to planetesimal formation.

Posted on Mar 31, 2017 in Seminars

Talk Title: Challenges in computational planet formation; from disk instability to planetesimal formation. Abstract: I will discuss recent progress in modeling a number of important regimes in planet formation.  First I will report on recent developments in the disk instability model for giant planet formation, which is attractive to explain extrasolar gas giants on wide orbits. I will show how new Lagrangian hydrodynamical techniques can solve the long standing issue of non-convergence of the critical cooling for disk fragmentation. The same hydro method allows to study the combination...

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April 21, 2017: A Young K-Ar Age of Jarosite in the Mojave 2 Sample at Gale Crater, Mars

Posted on Mar 31, 2017 in Seminars

Talk Title: A Young K-Ar Age of Jarosite in the Mojave 2 Sample at Gale Crater, Mars Abstract: Although the relative timing of surface processes on Mars is relatively well constrained, the absolute timing of these events remains uncertain due to the inherent limitations of crater counting geochronology. The Curiosity rover has the demonstrated ability to measure the bulk K-Ar ages of rocks; an age of 4.21±0.35 Ga was measured early in the mission. A recent sample collected by Curiosity contains a relatively large proportion of jarosite, so a two-step heating experiment was conceived to allow...

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April 14, 2017: Generating Magnetic Fields in Earth, Venus, and Super-Earth Exoplanets

Posted on Mar 31, 2017 in Seminars

http://web.gps.caltech.edu/~jorourke/index.html 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.    

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April 07, 2017: Elusive Earths: Taking the Galactic Exoplanet Census

Posted on Mar 31, 2017 in Seminars

http://web.ipac.caltech.edu/staff/christia/ Talk Title: Elusive Earths: Taking the Galactic Exoplanet Census Abstract: 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...

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The iPLEX Spring 2017 Guest Speaker Schedule

Posted on Mar 31, 2017 in 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...

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March 17, 2017: Young Planets in Protoplanetary Disks: Theory Confronts Observations

Posted on Jan 18, 2017 in Seminars

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.

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January 20, 2017: Eccentric rings and disks

Posted on Jan 15, 2017 in Seminars

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.

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February 24 2017: The Rotation Period of Hi’iaka, Haumea’s Largest Satellite & Rotationally Disrupting Bodies

Posted on Jan 12, 2017 in Seminars

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.

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March 10 2017: Meteorite Paleomagnetism

Posted on Jan 4, 2017 in Seminars

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

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March 03 2017: A Transiting Extrasolar Ring System

Posted on Jan 4, 2017 in Seminars

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...

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February 17, 2017: Ice Nucleation: From The Earth To Mars And Beyond

Posted on Jan 4, 2017 in Seminars

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.

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February 10, 2017: Evidence for aqueous alteration and ice-rock fractionation on (1) Ceres

Posted on Jan 4, 2017 in Seminars

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.

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February 03, 2017: Characterizing Middle And Outer Solar System Minor Bodies As Probes For Solar System Evolution

Posted on Jan 4, 2017 in Seminars

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.

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January 27, 2017: Probing The Comet-Asteroid Continuum

Posted on Jan 4, 2017 in Seminars

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.

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The iPLEX Winter 2017 Guest Speaker Schedule

Posted on Dec 27, 2016 in Seminars

The iPLEX Winter 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. The first and last days of classes for the Winter 2017 are January 9th 2017 and March 17th 2017, respectively.   Jan 13: No speaker/talk this week Jan 20: 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...

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