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Seminars

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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October 28th, 2016: Bi-stability of Earth and what life may have to do with it

Posted on Sep 5, 2016 in Seminars

We consider a model of the evolution of the Earth including the water cycle and continental growth along with mantle convection and thermal evolution. The water cycle and continental growth and erosion are strongly non-linear feedback cycles that are coupled through the subduction of water carrying sediments and oceanic crust. Mantle viscosity is taken temperature and water concentration dependent. We plot our results in a series of phase planes spanned by mantle water concentration and continental coverage. The system starts with one fixed point in the phase plane and evolves to three fixed...

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December 2nd, 2016: Comet formation theories in the light of the Rosetta mission

Posted on Sep 5, 2016 in Seminars

Measurements from the Rosetta spacecraft at comet 67P show a low density, bilobate body containing volatile gases in addition to water. I will discuss implications of the Rosetta data for comet formation models.

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November 4th, 2016: Early Formation of the Moon 4.52 billion years ago

Posted on Sep 5, 2016 in Seminars

New isotopic measurements of lunar zircons require formation of the Moon within the first ~60 million years of solar system history. This age places the Moon-forming giant impact 100 million years earlier than many recent estimates.

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October 21st, 2016: Debris Disks and Distant Perturbers: The Transient State of the HD 106906 Disk

Posted on Sep 5, 2016 in Seminars

The HD 106906 system harbors an asymmetric disk and a very distant (>650 au) planetary-mass companion. We use collisional and dynamical simulations to investigate the interactions between the disk and the companion, and to use the disk’s observed morphology to place constraint’s on the companion’s orbit.

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October 14th, 2016: Solar System formation and evolution: hints on the origin of the diversity of planetary systems

Posted on Sep 5, 2016 in Seminars

I will present an outline of the major steps in the formation of the Solar System and its evolution towards the current structure. First, the generation of a global dichotomy, with multiple small (~Mars-mass) planetary embryos in the inner part and multi-­Earth-­mass giant planet cores in the outer part. Second, the onset of a dynamical barrier against the drift of icy particles into the inner system, due to the formation of proto-­Jupiter, which allowed the inner solar system to remain ice-­depleted despite the disk cooled during its evolution. Third, the inward migration of Jupiter,...

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October 7th, 2016: Large wind ripples on Mars: A record of atmospheric evolution

Posted on Sep 5, 2016 in Seminars

Large wind ripples on Mars are unlike any wind-blown sedimentary structures found in Earth’s sandy deserts. We propose that they form from the effect of wind drag on sand particles, such that preserved ripple stratification may shed light onto the early evolution of the martian atmosphere.

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September 30th, 2016: Origins of Gas Giant Compositions: The Role of Disk Location and Dynamics

Posted on Sep 5, 2016 in Seminars

The composition of planets is determined by and tightly linked to the composition of the protoplanetary disk in which they form. In the first part of my talk, I will discuss giant planet formation through core accretion. In the second part, I will explore how the composition and evolution of protoplanetary disks may affect the formation and chemical composition of giant planets.

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Academies’ ‘Search for Life Workshop’ Registration Open (5-6 December 2016)

Posted on Aug 26, 2016 in Seminars

No events to display. The Space Studies Board of the National Academies of Sciences, Engineering, and Medicine is hosting a workshop and poster session to explore the current status of activities to detect extraterrestrial life in the solar system and extrasolar planetary systems. The workshop will feature presentations from experts on the environmental limits of life, habitable environments in the solar system and beyond, extraterrestrial biosignatures, and life detection techniques and instrumentation.   The workshop will take place at the Beckman Center in Irvine, CA on December...

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The iPLEX Fall 2016 Guest Speaker Schedule

Posted on Aug 19, 2016 in Seminars

The iPLEX Fall 2016 Guest Speaker Schedule: Please join us on Fridays from 12 to 1pm in the UCLA Geology Building (Room 3-814), followed by lunch 1 to 2pm. Sep 23: No speaker/talk this week Sep 30: Ana Piso (UCLA) “Origins of Gas Giant Compositions: The Role of Disk Location and Dynamics” The composition of planets is determined by and tightly linked to the composition of the protoplanetary disk in which they form. In the first part of my talk, I will discuss giant planet formation through core accretion. In the second part, I will explore how the composition and evolution of...

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March 11th, 2016: From “Honey Planets” to a Geodynamic Origin of Life

Posted on Feb 9, 2016 in Seminars

I present some novel insights based on first principles, parameterized 1D thermal history, and 3D spherical mantle convection evolution models, which raise doubt concerning many crucial assumptions commonly used in planetary geodynamics and allow for a new view on the thermal and tectonic evolution of rocky planets in our solar system and beyond. The new approach leads to massive rocky planets (Earth and bigger) remaining hotter for longer and plate tectonics being ideally initiated early on in the first 0.1-1Gyr driven by core cooling and boosted by a dry mantle and a late delivery of...

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