PTYS/LPL Colloquium Schedule 2012/2013

DATE EVENT TIME
Tuesday, Aug 21 2012 LPL Colloquium:
TBA
Thursday, Aug 30 2012 LPL Colloquium: Dr. Rebecca Ghent
Dr. Rebecca Ghent
Associate Professor
Department of Earth Sciences
University of Toronto

"Regolith Accumulation on the Moon: Insights from Radar and Diviner Observations"

Abstract:
In this talk, I investigate the radar and thermal properties of continuous ejecta associated with young lunar craters. New data from Earth-based radar, LRO mini-RF, and the LRO Diviner thermal mapper allow us to constrain the thermophysical properties of the upper ~1m of regolith, and allow determination of the depth of regolith covering ejecta blocks from young craters. This in turn yields new insights into the rate of regolith accumulation.

Host: Shane Byrne

Refreshments served at 3:30p.m.in the Kuiper atrium.

Kuiper Space Sciences: Room 308
3:45 pm
Tuesday, Sep 4 2012 LPL Graduate Student Colloquium:
Kelly Miller
Graduate Student in the Department of Planetary Sciences
A Review of: "Organic Synthesis via Irradiation and Warming of Ice Grains in the Solar Nebula"
Ciesla & Sandford, 2012, Science, vol. 336 no. 6080, pp. 452-454

Sarah Morrison
Graduate Student in the Department of Planetary Sciences
"Long Term Orbital Evolution and Final Destination Within a Planet's Resonance Overlap Chaotic Zone"

Kuiper Space Sciences: Room 308
3:45 pm
Tuesday, Sep 11 2012 LPL Colloquium:
Dr. Brad Hansen
Associate Professor
Department of Physics and Astronomy
University of California, Los Angeles

"Looking for the Connections Between Hot Jupiters, Kepler Candidates and the Solar System"

Host: Isamu Matsuyama

Kuiper Space Sciences: Room 308
3:45 pm
Tuesday, Sep 18 2012 LPL Graduate Student Colloquium:
Sky Beard
Graduate Student in the Department of Planetary Sciences
"40Ar-39Ar Studies of Intermediate Sized Clasts from Lunar Breccia"

James Keane
Graduate Student in the Department of Planetary Sciences
A Review of: "A Rapid Disappearance of a Warm, Dusty Circumstellar Disk" Melis et al. 2012, Nature 487, 74-76


Kuiper Space Sciences: Room 308
3:45 pm
Tuesday, Sep 25 2012 LPL Colloquium: Dr. Sandra Pizzarello
Dr. Sandra Pizzarello
Emeritus Professor and Research Professor
Arizona State University

"On the Rocks: The Organic Materials of Carbonaceous Meteorites"

Abstract:

The soluble and insoluble organic compositions of Carbonaceous Chondrites have been studied and extensively characterized for over forty years now. However, little is still known of whether or how the syntheses of these meteorite organics, which likely spanned solar as well as presolar cosmic environments, might relate to the concomitant evolution of their host mineral phases. Recent results and surprising new data have changed our general assumptions on this topic; they will be presented and discussed.

Host: Tom Zega

Kuiper Space Sciences: Room 308
3:45 pm
Tuesday, Oct 2 2012 LPL Colloquium: Dr. Isamu Matsuyama
Dr. Isamu Matsuyama
Assistant Professor
Lunar and Planetary Laboratory

"Global figure and interior structure of the Moon"

Abstract:
The unusual shape of the Moon given its present rotational and orbital state has been explained as due to a fossil figure preserving a record of remnant rotational and tidal deformation. However, previous studies assume infinite rigidity and ignore deformation due to changes in the rotational and tidal potentials. I will present a physical model that takes into account this deformation.

One of the primary science objectives of the Gravity Recovery and Interior Laboratory (GRAIL) mission is to determine the structure of the lunar interior. In the second part of the talk, I will discuss the use of Bayesian probability theory and multiple geophysical constraints, including the anticipated improvement in the determination of the k2 Love number, to calculate the probability density function of interior structure parameters.

Host: Bill Hubbard

Kuiper Space Sciences: Room 308
3:45 pm
Monday, Oct 8 2012 TAP Colloquium: Prof. Doug Lin
Prof. Doug Lin
University of California, Santa Cruz

"Origin, Evolution, and Destiny of Close-in Super Earths"

Abstract:
Planetary astrophysics is the most exciting and fastest growing branch of astronomy today. New data obtained from systematic radial velocity surveys and Kepler transit surveys have led to the discovery of over 700 planets and 3000 additional candidates, many of which are multiple systems. Although their presence is ubiquitous around nearby stars, their kinematic and structure properties appear to be diverse.

Based on these rich data, I will present some theoretical analyses which may enable us to extract information about their origin, evolution, and structure. I will discuss the process of planet migration in evolving protostellar disks, the interaction of stellar magnetic fields with protostellar disks and close-in planets, tidal evolution of close-in companions, the potential retention of volatile elements and loss of atmosphere. These effects are incorporated into population synthesis models and the construction of scenarios for the retention of close-in planets and the observed obliquity between stellar spins and planet's orbits.


Steward Observatory: Room N210
3:30 pm
Tuesday, Oct 9 2012 LPL Graduate Student Colloquium:
Michelle Thompson
Graduate Student in the Department of Planetary Sciences
A Review of: "Supernova Shock-Wave-Induced Co-formation of Glassy Carbon and Nanodiamond"
Stroud et al. 2011, Apj 738, L27

Donna Viola
Graduate Student in the Department of Planetary Sciences
A Review of: "Survival of Rock-Colonizing Organisms after 1.5 Years in Outer Space"
Onofri et al. 2012, Astrobiology 12, 5


Kuiper Space Sciences: Room 308
3:45 pm
Tuesday, Oct 16 2012 LPL Colloquium: Dr. Ofer Cohen
Dr. Ofer Cohen
Harvard-Smithsonian Center for Astrophysics

"The Extreme Space Environment of Close-in Exoplanets"

Abstract:
Since their first discovery, many exoplanets have been found at a close-in orbit around their parent star, where they essentially reside inside the stellar corona. The current search for Earth-like planets is focused on planets orbiting M-dwarf stars, where the habitable zone, (the distance range where liquid water could be found on the planetary surface) is located at a close distance. However, M-dwarfs stars are magnetically active, so it is necessary to investigate how does the harsh space environment of these close-in planets may play a role in the planet's habitability. I will show a series of numerical simulations to study different aspects of the space environment of close-in planets, and the consequences of star-planet magnetic interaction. I will also show how electromagnetic processes in the upper atmospheres of close-in hot-jupiters can contribute to the atmospheric evaporation.

Host: Joe Giacalone

Kuiper Space Sciences: Room 308
3:45 pm
Monday, Oct 22 2012 TAP Colloquium:
Dr. Rebekah Dawson
Harvard-Smithsonian Center for Astrophysics

"Some Assembly Required: Nature's Instruction Booklet for Planetary Migration"

Abstract:
We once thought planets formed peacefully in situ in their proto-planetary disks and subsequently followed their orbits like clockwork. However, there is growing evidence that the typical planetary system forms with some
assembly required and undergoes a dynamical rearrangement through planetary "migration" processes, which may be smooth or violent.

Here I present two case studies that have enabled progress toward understanding Nature's instruction booklet for planetary migration:
1) searching for supereccentric hot Jupiter progenitors, and
2) reconstructing Neptune's migration history based on orbital eccentricities of Kuiper belt objects.


Steward Observatory: Room N210
4:00 pm
Tuesday, Oct 23 2012 LPL Colloquium: Dr. Lindsay P. Keller
Dr. Lindsay P. Keller
Johnson Space Center

"Cometary Dust: A Window to the Early Solar System"

Abstract:

Comets formed in the Kuiper Belt have long been considered to harbor the best preserved remnants of the Solar System starting materials because they accreted at >30 AU, where temperatures were on the order of 30 K. The small sizes of most comets and their origins in the outermost regions of the Solar System protected them from both significant internal heating by radioactive heat sources and nebular heating. Consequently, comets have escaped the extensive thermal and aqueous processes that have modified or destroyed most of the Solar System starting materials in meteorites. Cometary materials are likely to harbor the best preserved remnants of interstellar silicates and other building blocks of the Solar System.

Cometary dust samples have been the subjects of intensive laboratory study, both in the form of interplanetary dust particles (IDPs) collected in the Earth's stratosphere and direct samples of comet 81P/Wild-2 returned by the Stardust spacecraft. While the specific parent bodies of individual IDPs are unknown, the anhydrous chondritic-porous (CP) subset has been linked directly to cometary sources based on their compositions, dynamical histories, and infrared spectra. Other clear indications of the primitive nature of CP IDPs is their relatively high abundances of presolar materials including circumstellar silicates and preserved molecular cloud organic matter. Coordinated mineralogical, chemical and isotopic studies of these particles are used to establish the origins of their various components.

Host: Tom Zega

Kuiper Space Sciences: Room 308
3:45 pm
Monday, Oct 29 2012 TAP Colloquium:
Dr. Eugene Chiang
University of California, Berkeley

"Close-in Planets: From Hot Jupiters to Super Moons"

Abstract:
The closest-in planets, with periods as short as 10 hours, are now a well-established population, thanks to Doppler and transit surveys. They present a number of challenges: how did they form and achieve their tight orbits, and how do they evolve and survive in the face of intense irradiation from their parent stars? Although orbital migration is often invoked, the possibility of in-situ accretion deserves consideration, and I will review how rocky cores coagulate and acquire gaseous envelopes at the smallest disk radii.

In some cases, gas envelopes are susceptible to evaporation, and I will describe how close-in planets lose mass via thermal winds driven by stellar heating. The curious case of Kepler Input Catalog 12557548 --- which may represent the first example of a geologically active, Moon-sized planet in its final death throes --- is presented.


Steward Observatory: Room N210
4:00 pm
Tuesday, Oct 30 2012 LPL Colloquium: Dr. Candice Hansen
Dr. Candice Hansen
Senior Scientist
Planetary Science Institute

"Probing Enceladus' Plume with Stellar Occultations"

Abstract:
In 2005 Enceladus' water vapor plume was discovered in a collection of observations carried out by Cassini spacecraft instruments. This talk will begin with a short overview of what was learned by all the instruments, then focus on subsequent observations carried out by the UltraViolet Imaging Spectrograph (UVIS). The UVIS instrument has been used to observe 5 occultations of stars by the plume plus one solar occultation. Results include the detection of supersonic jets imbedded within the main plume.

Host: Alfred McEwen

Kuiper Space Sciences: Room 308
3:45 pm
Tuesday, Nov 6 2012 LPL Colloquium: Dr. Matthew Hedman
Dr. Matthew Hedman
Senior Research Associate
Cornell University

"What can Saturn's rings do for you?"

Abstract:
Saturn's rings are among the most picturesque structures in the outer solar system. However, planetary rings are not just pretty ornaments on the giant planets, they are also useful tools for addressing a wide variety of questions in planetary science. This talk will describe how observations of the rings by the Cassini Mission can provide insights into such diverse topics as planet migration in the early solar system, the distribution of small objects in the outer solar system, and the internal structure of giant planets.

Host: Richard Greenberg

Kuiper Space Sciences: Room 308
3:45 pm
Thursday, Nov 8 2012 LPL Colloquium: Dr. Bonnie Buratti
Dr. Bonnie Buratti
Principal Scientist/Senior Research Scientist
Jet Propulsion Laboratory

"The Composition of the Rain on Titan as revealed by Cassini VIMS"

Host: Shane Byrne

Kuiper Space Sciences: Room 308
3:45 pm
Monday, Nov 19 2012 TAP Colloquium:
Dr. Phil Arras
University of Virginia


Steward Observatory: Room N210
4:00 pm
Tuesday, Nov 20 2012 LPL Graduate Student Colloquium:
Gabriel Muro
Graduate Student in the Department of Planetary Sciences

A Review of: "Tectonics on Iapetus: Despinning, Respinning, or Something Completely Different"

K.N. Singer, W.B. McKinnon, Icarus, Vol. 216, Issue 1, pp. 198-211


Kuiper Space Sciences: Room 308
3:45 pm
Tuesday, Nov 27 2012 LPL Colloquium: Dr. Geoff Vallis
Dr. Geoff Vallis
Professor
Atmospheric and Oceanic Sciences Program
Princeton University

"Dynamics of the Ocean and Atmosphere on the Most Interesting Planet of All"

Abstract:
The driving of a planetary atmosphere is usually thermal. However, if the fluid is opaque to solar radiation, as with Earth's ocean, then the heating and cooling only occurs at the top of the fluid and the thermal forcing is very inefficient. On Earth the deep ocean would be virtually stagnant without wind forcing. We'll discuss these issues and offer a new, quantitative, semi-analytic theory for the deep circulation of the ocean.

Host: Adam Showman

Kuiper Space Sciences: Room 308
3:45 pm
Monday, Dec 3 2012 TAP Colloquium:
Dr. Mark Vogelsberger
Harvard University

Steward Observatory: Room N210
4:00 pm
Tuesday, Dec 4 2012 LPL Graduate Student Colloquium:
Cecilia Leung
Graduate Student in the Department of Planetary Sciences
"Mesoscale Meteorological Modeling at Gale Crater"

Ethan Schaefer
Graduate Student in the Department of Planetary Sciences
A Review of: "Hydrological Characteristics of Recurrent Slope Lineae on Mars: Evidence for Liquid Flow through Regolith and Comparisons with Antarctic Terrestrial Analogs"
Levy et al. 2012, Icarus 219 (1), 1-4


Kuiper Space Sciences: Room 308
3:45 pm
Monday, Jan 14 2013 TAP Colloquium:
Dr. Peter Behroozi
Stanford University

"Galaxy Star Formation Efficiency from z=0 to z=8"

Abstract:
We present a robust, self-consistent, semi-empirical model which matches observed galaxy stellar masses and star formation rates over nearly all of cosmic history. Key results include constraints on star formation rates as a function of halo mass, average star formation histories for galaxies from z=0 to z=8, and the buildup of the intracluster light as a function of halo mass and time. We also examine the connections between halo growth and galaxy growth, and we find that the universe's star formation history since z~4 can be explained by a star formation efficiency which is strongly dependent on mass but only weakly dependent on time. We discuss the implications of this latter finding, especially in terms of the impact on black hole/supernova feedback models and the impact on the shape of the cosmic star formation rate for 0 < z < 8.

Host: Desika Narayanan

TAP Colloquia


Steward Observatory: Room N210
4:00 pm
Tuesday, Jan 15 2013 LPL Colloquium: Dr. Victoria Hamilton
Dr. Victoria Hamilton
Section Manager, Planetary Physics
Southwest Research Institute

"Distribution, characteristics, and possible origin of Adirondack-class basalt in Gusev crater as observed from Mini-TES data"

Abstract:
More than 100 unique rock targets belonging to the olivine-rich Adirondack class have been identified using mid-infrared spectra from the Miniature Thermal Emission Spectrometer onboard the Mars Exploration Rover Spirit in Gusev crater. Rare rocks on the West Spur of the Columbia Hills and on the plains east of the Hills also belong to this class. I will present evidence that the Adirondack-class basaltic lavas may have had their origin at Apollinaris Tholus.

Linear modeling of Adirondack-class rock spectra shows only minor variations in mineralogy and the primary phases identified are consistent with olivine basalt having an average olivine composition of ~Fo45. We used factor analysis and target transformation to identify variability within a single class of rocks for the first time, and we find that olivine abundance varies independently of a basaltic matrix. A spectral component attributable to optically thin dust on rocks has a greater effect on Mini-TES spectra than previously recognized leading to the conclusion that spectral mixing is not completely linear. This thin dust coating results in the overestimation of sulfate and olivine fractions and the underestimation of plagioclase feldspar, although linear mixing appears to successfully replicate the majority of the observed signal. Published TES spectra of low albedo, low dust cover, olivine-bearing materials do not exhibit the spectral telltales of non-linear behavior, probably because orbital spectra represent mostly mobile regolith that has not accumulated a sufficient dust cover over ~3 x 6 km areas.

Host: Shane Byrne

Kuiper Space Sciences: Room 308
3:45 pm
Tuesday, Jan 22 2013 LPL Colloquium: Dr. Ilaria Pascucci
Dr. Ilaria Pascucci
Assistant Professor
Lunar and Planetary Laboratory

"The Dispersal of Protoplanetary Disks - Impact on Planetary Architectures"

Abstract:
Astronomical observations have demonstrated that viscous accretion, the dominant driver of early disk evolution, cannot account for the final dispersal of protoplanetary disks. In this talk, I will discuss the physical processes proposed to explain these late stages of disk evolution. I will seek constraints from disk observations and from the Solar System to evaluate their role in clearing protoplanetary material. I will also present new diagnostics to measure the rate at which disks lose their mass. Finally, I will discuss how disk clearing impacts planet migration and shapes planetary architectures.

Kuiper Space Sciences: Room 308
3:45 pm
Monday, Jan 28 2013 TAP Colloquium:
Dr. Konstantin Batygin
Caltech

"The Origin of Orbital Obliquity in Hot Exoplanetary Systems"

Abstract:
The presence of gaseous giant planets whose orbits lie in extreme proximity to their host stars ('hot Jupiters"), can largely be accounted for by planetary migration, associated with viscous evolution of proto-planetary nebulae. Recently, observations of the Rossiter-McLaughlin effect during planetary transits have revealed that a considerable fraction of detected hot Jupiters reside on orbits that are misaligned with respect to the spin-axes of their host stars. This observational fact has cast significant doubts on the importance of disk-driven migration as a mechanism for production of hot Jupiters, thereby reestablishing the origins of close-in planetary orbits as an open question.

In this talk, I will show that misaligned orbits can be a natural consequence of disk migration. The argument rests on an enhanced abundance of binary stellar companions in star formation environments, whose orbital plane is uncorrelated with the spin axes of the individual stars. I will construct a conservative model for the dynamical evolution of a self-gravitating proto-planetary disk under perturbations from a distant stellar companion and demonstrate that the gravitational torques of the binary companion act to misalign the orbital plane of the disk relative to the spin pole of the star.

Host:
Tami Rogers, tami@lpl.arizona.edu

TAP Colloquia



Steward Observatory: Room N210
4:00 pm
Tuesday, Jan 29 2013 LPL Colloquium: Dr. Nathaniel Putzig
Dr. Nathaniel Putzig
Southwest Research Institute

"CAT scans of Mars: Three-dimensional imaging of the polar layered deposits with SHARAD"

Abstract:
Orbital sounding radar investigations typically acquire data along a ground track and display it as a radargram, an image format with distance along track on the X axis and returned-signal power as a function of range delay (sometimes converted to depth) along the Y axis. Where coverage is sufficiently dense, collections of such two-dimensional (2-D) cross-sectional views can be used to map out subsurface features in three dimensions, which has been done with some success for the Martian polar layered deposits. However, individual radargrams are often obfuscated by returns from off-nadir features from nearby topography such as craters or polar troughs. I will present an alternative approach, where the collection of 2-D data is binned into a horizontal grid over a given surface area, transforming it into a 3-D volume. Once the data are properly co-registered and adjusted for any orbit-to-orbit power or timing differences, advanced 3-D image-correction processing can be applied to the volume, largely correcting off-nadir returns and greatly enhancing interpretability of the data. My presentation will include an overview of results obtained from the conventional approach, first results from the 3-D approach applied to Planum Boreum, and arguments for extending the 3-D approach to Planum Australe.

Host: Shane Byrne

Kuiper Space Sciences: Room 308
3:45 pm
Tuesday, Feb 5 2013 LPL Graduate Student Colloquium:
Davin Flateau
Graduate Student in the Department of Planetary Sciences
Mapping Extrasolar Storms: Spitzer Exploration of Brown Dwarf Variability

Jess Vriesema
Graduate Student in the Department of Planetary Sciences
A Review of: "Time-Distance Seismology of the Solar Corona with CoMP"
Tomczyk and McIntosh 2009, ApJ 697, 1384


Kuiper Space Sciences: Room 308
3:45 pm
Tuesday, Feb 12 2013 LPL Graduate Student Colloquium:
Sky Beard
Graduate Student in the Department of Planetary Sciences
A Review of: "A Sawtooth-like Timeline for the First Billion Years of Lunar Bombardment" Morbidelli et al. (2012) Earth Planet Sci Lett 355-356, 144-151


Sarah Morrison
Graduate Student in the Department of Planetary Sciences
A Review of: "Can Planetary Instability Explain the Kepler Dichotomy?"
Johansen et al. (2012) ApJ 758, 39


Kuiper Space Sciences: Room 308
3:45 pm
Thursday, Feb 14 2013 LPL Colloquium:
Dr. Catherine Neish
Postdoctoral Fellow
NASA Goddard Space Flight Center

"Titan's Crater Makeover"

Abstract:
When Cassini arrived at Titan in 2004, it revealed a varied and active world previously unseen. Unique among the icy satellites, Titan's surface shows evidence for extensive modification by fluvial and aeolian processes. Erosion likely contributes to the noticeable lack of craters on Titan, complicating age dating of its surface. Indeed, many of the craters that have been identified on Titan's surface appear to be altered by fluvial erosion, mass wasting, burial by dunes and/or submergence in seas. In this talk, I present our current understanding of the crater population on Titan, and discuss how we are using these celestial scars to quantify the amount and types of erosion occurring on its surface. Understanding erosion on Titan will have implications for our understanding of the evolution of its atmosphere, since the presence of hydrocarbons in the atmosphere is necessary for both fluvial and aeolian landscape modification. The present inventory of methane in Titan's atmosphere would be depleted photochemically on timescales of millions of years, so resupply from endogenic or exogenic sources may be needed to explain the observed amount of erosion.

Host: Shane Byrne

Kuiper Space Sciences: Room 308
3:45 pm
Friday, Feb 15 2013 Brown Bag Colloquium:
Dr. Catherine Neish
Postdoctoral Fellow
NASA Goddard Space Flight Center

Radar Love: Mini-RF Observes the Moon

Synthetic aperture radar (SAR) represents a unique way to observe the surface of planets. Using ground-based and orbital platforms, radars have provided new information about the topography, composition, and surface roughness of our planetary neighbors, as well as our own world. In June 2009, NASA launched the Lunar Reconnaissance Orbiter (LRO) carrying the Mini-RF synthetic aperture radar. Since then, Mini-RF has imaged two-thirds of the Moon at 30 m resolution, in both polar and non-polar regions. In this talk, I will summarize the discoveries made by Mini-RF in its first three years of operations. In particular, I will discuss (a) how the unusual radar properties of ice may lead to its detection in the permanently shadowed regions at the poles of the Moon, and (b) how new observations of lunar impact melts are leading to a better understanding of the impact cratering process.


Kuiper Space Sciences: Room 309
12:00 pm
Monday, Feb 18 2013 Brown Bag Colloquium:
Dr. Travis Barman
Assistant Astronomer
Lowell Observatory

Characterizing the Atmospheres of Transiting Planets

Abstract

Planets are now routinely found orbiting a variety of stellar hosts and a small fraction of these are amenable to atmospheric study. Theoretical models of giant planet atmospheres are evolving in tandem with the observations and are playing an ever increasing role in giant planet characterization. I will discuss how these models and precise observations of planet radii and fluxes are combined to obtain information about the chemical composition and thermal structure of transiting planets. Observations from Spitzer, Hubble, and several large ground-based telescopes have led to useful limits on important atmospheric constituents like water, methane, carbon monoxide for a few systems. I will describe how these observations compare with model predictions and how improvements might be achieved through new modeling endeavors and dedicated ground-based efforts.

Kuiper Space Sciences: Room 309
12:00 pm
Tuesday, Feb 19 2013 LPL Colloquium:
Dr. Travis Barman
Assistant Astronomer
Lowell Observatory

Host: Caitlin Griffith

Direct Imaging and Spectroscopy of Extrasolar Planets

Abstract

Gas giants in wide orbits (> 5 AU) have now been directly imaged around young nearby stars. This, however, is just the beginning. New instruments, tailor made for high-contrast imaging, are coming online this year and will reveal dozens of young planets. These instruments will also provide low resolution near-IR spectra of each new planet, revealing a wealth of information across a wide range of planet masses and ages. To illustrate the great potential of direct imaging, this talk will focus on recent near- infrared photometry and spectroscopy of the planets orbiting the young (~ 30 Myr) star HR8799. Ground-based observations have allowed the characterization of the planets' bulk properties along with their atmospheric structure. New spectroscopic data of HR8799c will be presented that contain numerous, well-resolved, molecular lines. These data reveal the chemical composition of the planet's atmosphere
(in particular the carbon and oxygen abundances) and may help distinguish between core-accretion and gravitational instability as the most likely formation mechanism.

Kuiper Space Sciences: Room 308
3:45 pm
Thursday, Feb 21 2013 LPL Colloquium:
Dr. Matthew Hedman
Senior Research Associate
Cornell University

Host: Renu Malhotra

Studying Saturn's Structure with Resonances in the Rings

Abstract:

Saturn's rings possess a wide array of structures and patterns sculpted by various combinations of particle interactions and outside forces. While the origin of many ring features remain obscure, certain distinctive patterns appear to be generated by asymmetries or oscillations within Saturn itself. Periodic brightness variations in two tenuous rings appear to be coupled to variations in Saturn's radio emissions, and thus probably track asymmetries in Saturn's magnetosphere. Meanwhile, spiral patterns in the innermost parts of Saturn's dense main rings have the right morphologies and motions to be generated by normal mode oscillations within the planet. These structures provide new avenues for exploring the internal structure of giant planets.

Kuiper Space Sciences: Room 308
3:45 pm
Friday, Feb 22 2013 Brown Bag Colloquium:
Dr. Matthew Hedman
Senior Research Associate
Cornell University

Host: Renu Malhotra

Examining Enceladus' Emissions in the Near-Infrared

Abstract:

The plumes of water vapor and ice grains spewing out from cracks near Enceladus' south pole are one of Cassini's most remarkable discoveries. The Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini Spacecraft has observed the near-infrared light scattered by Enceladus' plumes multiple times under a relatively wide range of viewing conditions. These spectral data reveal that particles of different sizes have different spatial distributions within the plume, which provides clues about how the particles are being accelerated beneath the moon's surface. Furthermore, the plume's total brightness varies as Enceladus moves around its eccentric orbit, indicating that tidal forces play a role in controlling the moon's geological activity.

Kuiper Space Sciences: Room 309
12:00 pm
Tuesday, Feb 26 2013 LPL Graduate Student Colloquium:
James Keane
Graduate Student in the Department of Planetary Sciences
"From Classical Disks to Transition Disks: An Increasing Dust to Gas Ratio?"


Ethan Schaefer
Graduate Student in the Department of Planetary Sciences
A Review of: "Gasa Impact Crater, Mars: Very Young Gullies Formed from Impact into Latitude-Dependent Mantle and Debris-Covered Glacier Deposits?"
Schon and Head (2012), Icarus, 218, 459-477


Kuiper Space Sciences: Room 308
3:45 pm
Monday, Mar 4 2013 TAP Colloquium: Dr. Charlie Conroy:
Dr. Charlie Conroy
University of California, Santa Cruz

Our understanding of the stellar populations of unresolved galaxies is fundamentally limited by our lack of knowledge of the stellar initial mass function (IMF), and its variation with environment and epoch. In this talk I will present a technique that provides direct measurements of the low-mass IMF (~0.1-1 Msun) in unresolved stellar systems. When this technique is applied to high-quality optical-NIR spectra of nearby early-type galaxies, evidence is found for an IMF that is substantially more "bottom-heavy" than the Galactic IMF. I will also discuss ongoing work aimed at measuring elemental abundances (including C, N, O, Na, Mg, Ca, Ti, Cr, Mn, Fe, Sr, and Ba) of these galaxies, with the goal of constraining their formation histories.

Steward Observatory: Room N210
4:00 pm
Monday, Mar 4 2013 Brown Bag Colloquium: Dr. Christopher Hamilton:
Dr. Christopher Hamilton

Planetary Geodynamics Laboratory, NASA Goddard Space Flight Center
Department of Astronomy, University of Maryland, College Park

Host: Shane Byrne

Volcanism on Jupiter's Moon Io

Io is the most volcanically active body in the Solar System, but unlike the Earth, Io does not exhibit evidence of plate tectonics and its internal heating comes primarily from tidal dissipation rather than radiogenic sources. Nonetheless, volcanic systems on Io exhibit some similarities to mantle-plume fed hotspots on Earth. Here, volcanism on Io is compared to the Hawaiian hotspot and then the spatial distributions of Ionian hotpots are examined in detail to test predictions from a range of interior tidal heating models. Results show a statistically significant eastward offset between locations of enhanced volcanism and predicted surface heat flux maxima. Possible explanations for this offset are explored along with implications for other tidally heated bodies.

Kuiper Space Sciences: Room 309
12:00 pm
Tuesday, Mar 5 2013 LPL Colloquium: Dr. Christopher Hamilton
Dr. Christopher Hamilton

Planetary Geodynamics Laboratory, NASA Goddard Space Flight Center
Department of Astronomy, University of Maryland, College Park

Host: Shane Byrne

Volcano-Ice Interactions on Earth and Mars

Volcanism is a fundamental planetary process that provides insight into the thermal, surficial, and atmospheric evolution of terrestrial bodies. Interactions between volcanoes and their near-surface water or ice can also produce distinctive landforms that are indicative of environments at the time of the eruption. Here, the products of explosive lava-water interactions in Iceland are compared to analogous structures on Mars to infer martian paleoenvironmental conditions, including ground ice depths and obliquity constraints. The broader implications of Amazonian-age flood lavas in Elysium Planitia are also considered to better constrain the volcanic history of Mars.

Kuiper Space Sciences: Room 308
3:45 pm
Thursday, Mar 7 2013 LPL Colloquium: Dr. Amaya Moro-Martin
Dr. Amaya Moro-Martin
Ramon y Cajal Fellow
Center for Astrobiology (INTA-CSIC)

"Seeing Worlds in Grains of Sand"

Abstract:
Debris disks are disks of dust that surround mature stars. From lifetime arguments it is inferred that the dust is not primordial but must originate from the collision/sublimation of planetesimals (that could be similar to the asteroids, comets and KBOs in our solar system). The presence of debris around stars of a wide range of masses (from the progenitors of white dwarfs to M dwarfs) indicates that planetesimal formation is a robust process that can take place under a wide range of conditions. Debris disks can help us learn about the diversity of planetary systems shedding light on the frequency and timing of planetesimal formation, their dynamical evolution, in some cases the parent bodies properties, the location of the dust-producing planetesimals and give hints on the presence of perturbing planetary companions. Of particular interest is the study of debris around stars known to harbor planets, the search for giant planets in debris disks systems and the exchange of debris between planetary systems.

Host: Ilaria Pascucci

Kuiper Space Sciences: Room 308
3:45 pm
Friday, Mar 8 2013 Special LPL Colloquium: Dr. Amaya Moro-Martin:
Dr. Amaya Moro-Martin
Ramon y Cajal Fellow
Center for Astrobiology (INTA-CSIC)

Host: Ilaria Pascucci

Topic: Debris Disks

Kuiper Space Sciences: Room 309
3:30 pm
Monday, Mar 18 2013 TAP Colloquium: Dr. Lars Hernquist:
Dr. Lars Hernquist
Harvard University

Steward Observatory: Room N210
4:00 pm
Monday, Mar 25 2013 TAP Colloquium:
TBA

Steward Observatory: Room N210
4:00 pm
Monday, Mar 25 2013 Brown Bag Colloquium: Dr. Vladimir Florinski:
Dr. Vladimir Florinski
Assistant Professor
University of Alabama, Huntsville

Host: Randy Jokipii

The Physics of the Heliopause

The heliopause is a plasma boundary separating the region of space controlled by the Sun's expanding atmosphere (the solar wind) from the interstellar cloud surrounding our star. It is likely that the plasmas on each side of the boundary have vastly different bulk properties and are in very different states of turbulent agitation. Last year Voyager 1 reported a series of energetic particle dropout events followed by a crossing of a sharp plasma boundary, that may have been the heliopause, or another, yet unknown interface. The plasma on the far side of the boundary was much less turbulent than what was observed previously in the heliosheath. Coincident with the boundary crossing was an almost complete disappearance of energetic particles produced in the heliosphere (such as anomalous cosmic rays), and a simultaneous increase in galactic cosmic-ray intensity. I will discuss these new results and suggest possible theoretical interpretations of the particle dropout events.

Kuiper Space Sciences: Room 309
12:00 pm
Tuesday, Mar 26 2013 LPL Colloquium: Dr. Vladimir Florinski
Dr. Vladimir Florinski*
Assistant Professor
University of Alabama, Huntsville

Host: Randy Jokipii

Exploring the boundary of the solar system

A momentous event is unfolding some 123 astronomical units from the Sun. For the first time a space probe is leaving the confines of the heliosphere and entering interstellar space. Over the past decade the twin Voyager probes have confirmed experimentally the existence of the solar wind termination shock and the region of compressed and heated plasma beyond, known as the heliosheath. Voyager results have also challenged previously accepted theories of the origin, properties, and acceleration mechanism of energetic charged particle populations in the outer heliosphere. A classic example is the theory anomalous cosmic rays (ACRs) which underwent a substantial revision following Voyager discoveries.

In this talk I will present an overview of the physics of the heliospheric interface from a theoretical and modeling perspective. I will discuss the plasma flow structure and magnetic field topology inside the heliosheath and beyond, and their imprint on the anomalous and galactic cosmic-ray populations. I will also review recent modeling activities and computational infrastructure development by my research team at the UA Huntsville.

*Contributions to this work by X. Guo, F. Alouani-Bibi and U. Senanayake is acknowledged.

Kuiper Space Sciences: Room 308
3:45 pm
Monday, Apr 1 2013 TAP Colloquium: Dr. Yoram Lithwick:
Dr. Yoram Lithwick
Northwestern University



Steward Observatory: Room N210
4:00 pm
Monday, Apr 1 2013 Brown Bag Colloquium: Dr. Edwin Kite:
Dr. Edwin Kite
Postdoctoral Scholar
California Institute of Technology

Host: Alfred McEwen

Climate instability on tidally locked exoplanets (& closer to home?)



Kuiper Space Sciences: Room 309
12:00 pm
Tuesday, Apr 2 2013 LPL Colloquium: Dr. Edwin Kite
Dr. Edwin Kite
Postdoctoral Scholar
California Institute of Technology

Host: Alfred McEwen

Mars and the problem of planetary habitability

It is not known whether Earth's long-term climate stability is rare or common. Kepler data suggest many Earth-radius habitable-zone planets lie within reach of JWST. The fraction of these that are habitable depends on the unknown processes that regulate long-term environmental stability. Mars' sedimentary record is the only known archive of a major planetary habitability transition. No rivers flow on today's Mars, but rovers and orbiters have found >3 Ga-old sedimentary rocks, dry rivers and paleolakes, and aqueous minerals. The nature of the early wet era, the processes that allowed surface liquid water, and the cause of climate deterioration are all unknown.

In this talk, I will use a snowmelt model (ISEE-Mars) to understand the global environmental context of sedimentary rock formation on Mars. Greenhouse models struggle to maintain annual mean temperatures >273K on Early Mars, making snowmelt an attractive candidate water source for sedimentary-rock cementation. Snowmelt predicts that Mars never had a stable multibar atmosphere, consistent with results from our new paleobarometer. The "Curiosity" rover is currently exploring the moat encircling a 5km-high sedimentary rock mound in Gale Crater. This moat-and-mound pattern is common in Mars craters and canyons, but its origin is unknown. I will set out the evidence that moats and mounds grew together, shaped by slope winds down the crater and mound flanks. If time allows, I will discuss (rare) fluvial sediments that are anomalously recent. Results from a mesoscale model show these deposits may record transient, localized conditions, rather than a global return to wet conditions. Taken together, data and models hint at an early Martian climate comparable to the Antarctic Dry Valleys. The "Curiosity" rover will soon be in a position to test this hypothesis.

In combination, we now have the tools and the data to recover quantitative information about trends, rhythms and aberrations in Early Mars habitability. Billion-year-baseline time series from Mars and Earth are complementary to "snapshots" of exoplanet climates...and both will be needed to develop a science of habitability on planets-in-general.

Kuiper Space Sciences: Room 308
3:45 pm
Thursday, Apr 4 2013 LPL Colloquium: Dr. Kevin Walsh
Dr. Kevin Walsh
Research Scientist
Southwest Research Institute

Host: Dante Lauretta

The Grand Tack: Jupiter's migration to 1.5 AU, and how it shaped the inner solar system

A persistent difficulty in terrestrial planet formation models is creating Mars analogs with the appropriate mass: Mars is typically an order of magnitude too large in simulations. A recent study found that a small Mars can be created if the planetesimal disk from which the planets form has an outermost edge at 1.0 AU. However, that work and no previous work, can explain such a truncation of the planetesimal disk and preserve the asteroid belt. We show that gas-driven migration of Jupiter inward to 1.5 AU, before its subsequent outward migration, can truncate the disk and repopulate the asteroid belt. This dramatic migration history of Jupiter suggests that the dynamical behavior of our giant planets was more similar to that inferred for extra-solar planets than previously thought, as both have been characterized by substantial radial migration.

Kuiper Space Sciences: Room 308
3:45 pm
Friday, Apr 5 2013 Brown Bag Colloquium: Dr. Kevin Walsh: Disrupting Asteroids - forming satellites and families
Dr. Kevin Walsh
Research Scientist
Southwest Research Institute
Host: Dante Lauretta

Disrupting Asteroids - forming satellites and families




Kuiper Space Sciences: Room 309
12:00 pm
Monday, Apr 8 2013 TAP Colloquium:
TBA

Steward Observatory: Room N210
4:00 pm
Monday, Apr 8 2013 Brown Bag Colloquium: Dr. Nikku Madhusudhan:
Dr. Nikku Madhusudhan
Postdoctoral Fellow
Yale University

Host: Ilaria Pascucci

Super-Earth Interiors

Abstract:

Latest exoplanet surveys are revealing an abundance of low mass exoplanets in the galaxy. Besides hundreds of candidates discovered by the Kepler space telescope, masses and radii have been measured for about ten confirmed `super-Earths', exoplanets with masses between 1 and 10 Earth masses. Being closest analogs to rocky planets in the solar system, detailed characterization of super-Earths is one of the frontier areas of exoplanet science today. In this talk, I will present the latest constraints emerging on the interior structures and formation environments of currently known super-Earths. Their interiors span a wide range of compositions, from water worlds with thick volatile envelopes to super-Mercuries, lava planets, and diamond planets, testing the limits of our understanding of mineralogies and equations of state under exotic conditions. These constraints are made possible by precise measurements of masses, radii, and spectra of super-Earths, and elemental abundances of their host stars, together with new modeling techniques. I will discuss a new and comprehensive modeling approach which includes hybrid models of super-Earth interiors and non-gray atmospheres, as well as cosmochemistry of their formation environments. I will present a comparative analysis of several transiting super-Earths and will focus particularly on two super-Earths (GJ 1214b and 55 Cancri e) which represent distinct end-members in the thermo-chemical phase space. The implications of our results for the diversity of geochemical, geophysical, and astrobiological conditions on super-Earths will be discussed. I will outline key questions that define the future of super-Earth characterization, along with new avenues for theoretical, observational, and experimental efforts.

Kuiper Space Sciences: Room 309
12:00 pm
Tuesday, Apr 9 2013 LPL Colloquium: Dr. Nikku Madhusudhan
Dr. Nikku Madhusudhan
Postdoctoral Fellow
Yale University

Host: Ilaria Pascucci

Exoplanetary Atmospheres

Abstract:

Recent advances in exoplanet observations and theoretical methods are leading to unprecedented constraints on the physicochemical properties of exoplanetary atmospheres. Atmospheric properties derived from exoplanetary spectra provide critical clues regarding not only their chemical diversity and various atmospheric processes, but also their interior compositions and formation mechanisms. In this talk, I will present many of the latest results in this field, both in observations and theory, and will discuss the promising outlook for the future. I will present constraints on the elemental abundances, non-equilibrium chemistry, temperature inversions, atmospheric dynamics, and the presence of clouds/hazes, for a sizable ensemble of extrasolar planets---both transiting and directly imaged, and including gas giants, ice giants, and super-Earths. These constraints result from detailed theoretical modeling and interpretation of spectral data from extensive observational efforts using major ground-based and space-borne infrared instruments, a survey of which will be presented. I will also discuss how these atmospheric constraints are being used to develop new classification schemes for exoplanets, and to constrain conditions of their formation and subsequent evolution. The emerging picture of exoplanetary atmospheres and formation will be discussed vis-a-vis our understanding of planets in the solar system. The exciting prospects of characterizing exoplanetary atmospheres using current, upcoming, and future observational facilities will be discussed, along with several open questions of fundamental nature in the field.

Kuiper Space Sciences: Room 308
3:45 pm
Monday, Apr 15 2013 TAP Colloquium:
TBA

Steward Observatory: Room N210
4:00 pm
Tuesday, Apr 16 2013 LPL Colloquium: Dr. Channon Visscher
Dr. Channon Visscher
Research Scientist
Southwest Research Institute

Host: Adam Showman

Chemistry in impact-generated disks and planetary atmospheres

Chemical processes play a key role in shaping the observational and geochemical properties of planetary objects. Moreover, better understanding these processes may yield important clues about planetary formation and evolution. In this two-part talk, I will discuss new chemical models exploring 1) the chemistry of the impact-generated proto-lunar disk and 2) chemical processes in the upper atmospheres of giant planets inside and outside of the solar system. For both cases, the model results will be discussed in light of recently available observational constraints by exploring the physical and chemical processes that produced the elemental and isotopic abundance patterns observed in lunar materials, and the coupled photochemical, thermochemical, and dynamical processes that are responsible for the observational properties of planetary atmospheres.

Kuiper Space Science: Room 308
3:45 pm
Monday, Apr 22 2013 TAP Colloquium - Zhi-Yun Li: Protostellar Disk Formation in Magnetized Clouds
Zhi-Yun Li
University of Virginia

Protostellar Disk Formation in Magnetized Clouds

The formation of stars and planets are connected through disks. Disk formation, once thought to be a trivial consequence of angular momentum conservation, is greatly complicated by the magnetic field that is observed to be present in the dense, star-forming cores of molecular clouds. Indeed, in the simplest case of perfect coupling between the magnetic field and bulk neutral core material (the ideal MHD limit), both analytic work and numerical simulations have shown that the formation of rotationally supported disks is suppressed by excessive magnetic braking in dense cores magnetized to the observed level. The disk suppression leads to the so-called ``magnetic braking catastrophe'' in star formation. I will discuss possible resolutions to this problem proposed to date, including non-ideal MHD effects, misalignment between the magnetic field and rotation axis, turbulence-enhanced magnetic reconnection, and outflow stripping of the slowly rotating protostellar envelope. The conclusion is that how protostellar disks form and grow remains an open question.

Tap Colloquia

Steward Observatory: Room N210
4:00 pm
Tuesday, Apr 23 2013 LPL Graduate Student Colloquium:
Kelly Miller
Graduate Student in the Department of Planetary Sciences
"Trace Element Distribution in Meteoritic Sulfides via Laser Ablation ICP-MS"


Michelle Thompson
Graduate Student in the Department of Planetary Sciences
"Microstructural and Chemical Analysis of Soils from Itokawa: Evidence for Space Weathering"



Kuiper Space Sciences: Room 308
3:45 pm
Monday, Apr 29 2013 TAP Colloquium - Herve Dole: Latest Planck Cosmology Results: Galaxies and Clusters
Herve Dole
IAS Orsay

Latest Planck Cosmology Results: Galaxies and Clusters

I'll give an overview the latest Planck cosmology results (out in early April). In the 2nd half, I will focus on some selected topics about the "foregrounds", mainly galaxies (including high-redshift sources followed-up by Herschel), but also SZ clusters.

TAP Colloquia
4:00 pm
Tuesday, Apr 30 2013 LPL Graduate Student Colloquium:
Ali Bramson
Graduate Student in the Department of Planetary Sciences

A Review of: "A New Method to Determine the Direction of Impact: Asymmetry of Concentric Impact Craters as Observed in the Field (Lokne), on Mars, in Experiments, and Simulations"
Ormo, Rossi & Housen (2013), Meteoritics & Planetary Science, 48(3): 403-419


Donna Viola
Graduate Student in the Department of Planetary Sciences

"Distribution of Expanded Secondary Craters, Arcadia Planitia, Mars"



Kuiper Space Sciences: Room 308
3:45 pm
Wednesday, May 1 2013 LPL Colloquium: Surface Compositions of Kuiper Belt Objects
Emily Schaller, Cal Tech, will discuss: “Surface Compositions of Kuiper Belt Objects.”

Abstract
Unlike main-belt asteroids, Kuiper Belt Objects (KBOs) are not easily categorized into compositional classes by their spectroscopic signatures. While some KBOs are large enough to retain volatile ices on their surfaces and can possess thin atmospheres (such as on Pluto), the vast majority of KBOs have surfaces dominated by involatile water ice and/or dark, spectrally featureless material. Recently, however, new spectroscopic observations have provided insight into the formation and evolution of many of these objects.

In this talk, I will discuss our recent spectroscopic observations of KBOs and what they have revealed about how giant collisions, UV photolysis, and atmospheric escape have shaped the surfaces of these bodies.

Refreshments will be served at 3:15 p.m. in the north corner of the atrium.

Please contact Ann Barringer if you wish to meet with the speaker.

Kuiper: Room 308
3:30 pm