The iPLEX Spring 2017 Guest Speaker Schedule

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

Emmanuel Masongsong’s Artwork Makes The Cover of Journal of Geophysical Research

UCLA Staff and Researcher, Emmanuel V. Masongsong’s artwork has made the cover of the Journal of Geophysical Research (JGR) which is a major AGU publication journal.
UCLA EPSS research findings are featured on the February 2017 cover of the Journal of Geophysical Research: Space Physics. The study describes the properties of a newly discovered form of the northern lights, called throat aurora, on the dayside of Earth facing the sun (upward, out of frame). Using observations on the ground and in interplanetary space, the aurora are postulated to form through a novel combination of plasma flows inside and outside of the Earth’s magnetic field (the magnetosphere). Under certain conditions, solar wind interactions at the bow shock (~2 Earth widths upstream of the magnetosphere) can produce fast jets of hot plasma that perturb the outer boundary of the magnetosphere, as shown by previous UCLA EPSS studies. Sometimes cooler plasma “fingers” within Earth’s magnetosphere extend outward towards this boundary. The interaction of these two plasmas manifests as throat aurora, with radial spokes uniquely aligned along the north-south longitudinal axis.
MasongsongJGRcover

Picture caption: “Observational properties of a newly discovered auroral form near local noon, called throat aurora, revealing combined contributions for its generation from inside and outside of the magnetosphere. The image gives a schematic summarizing the physical process leading to the formation of throat aurora. From Han et al. [pp. 1853–1870, doi: 10.1002/2016JA023394 ]. Image credit: E. Masongsong, H. Hietala (UCLA EPSS), D.-S. Han (Polar Research Institute of China).”
[pp. 1853–1870, doi: 10.1002/2016JA023394].

UCLA Professor Jonathan Arnou In The News

Experiment resolves mystery about wind flows on Jupiter

Using a spinning table and a massive garbage can, UCLA geophysicist leads team in simulating the planet’s atmosphere

Jupiter+south+pole,+credit,+Jonathan+Aurnou_mid

Views Jupiter’s south pole (upper left and lower right) and images from the lab experiment to re-create the planet’s winds (upper right and lower left). Image Credit: Jonathan Arnou

Jupiter’s colorful, swirling winds known as “jets” have long puzzled astronomers.

One mystery has been whether the jets exist only in the planet’s upper atmosphere — much like the Earth’s own jet streams — or whether they plunge into Jupiter’s gaseous interior. If the latter is true, it could reveal clues about the planet’s interior structure and internal dynamics.

Now, UCLA geophysicist Jonathan Aurnou and collaborators in Marseille, France, have simulated Jupiter’s jets in the laboratory for the first time. Their work demonstrates that the winds likely extend thousands of miles below Jupiter’s visible atmosphere.

This research is published online today in Nature Physics.

“We can make these features in a computer, but we couldn’t make them happen in a lab,” said Aurnou, a UCLA professor of Earth, planetary and space sciences, who has spent the past decade studying computer models of swirling winds. “If we have a theoretical understanding of a system, we should be able to create an analog model.”

The challenge to re-creating swirling winds in the lab was building a model of a planet with three key attributes believed to be necessary for jets to form: rapid rotation, turbulence and a “curvature effect” that mimics the spherical shape of a planet. Previous attempts to create jets in a lab often failed because researchers couldn’t spin their models fast enough or create enough turbulence, Aurnou said.

The breakthrough for Aurnou’s team was a new piece of laboratory equipment. The researchers used a table built on air bearings that can spin at 120 revolutions per minute and support a load of up to 1,000 kilograms (about 2,200 pounds), meaning that it could spin a large tank of fluid at high speed in a way that mimics Jupiter’s rapid rotation.

The scientists filled an industrial-sized garbage can with 400 liters (about 105 gallons) of water and placed it on the table. When the container spun, water was thrown against its sides, forming a parabola that approximated the curved surface of Jupiter.

“The faster it went, the better we mimicked the massively strong effects of rotation and curvature that exists on planets,” Aurnou said. But the team found that 75 revolutions per minute was a practical limit: fast enough to force the liquid into a strongly curved shape but slow enough to keep water from spilling out.

While the can was spinning, scientists used a pump below its false floor to circulate water through a series of inlet and outlet holes, which created turbulence — one of the three critical conditions for the experiment. That turbulent energy was channeled into making jets, and within minutes the water flow had changed to six concentric flows moving in alternating directions.

“This is the first time that anyone has demonstrated that strong jets that look like those on Jupiter can develop in a real fluid,” Aurnou said.

The researchers inferred that the jets were deep because they could see them on the surface of the water, even though they had injected turbulence at the bottom.

The researchers are looking forward to testing their predictions with real data from Jupiter, and they won’t have to wait long: NASA’s Juno space probe is orbiting Jupiter right now, collecting data about its atmosphere, magnetic field and interior. Initial results from the Juno mission were presented at the American Geophysical Union meeting in December in San Francisco, and Aurnou was there.

“The Juno data from the very first flyby of Jupiter showed that structures of ammonia gas extended over 60 miles into Jupiter’s interior, which was a big shock to the Juno science team,” Aurnou said. “UCLA researchers will be playing an important role in explaining the data.”

This year, Aurnou and his team will use supercomputers at Argonne National Laboratory in Argonne, Illinois, to simulate the dynamics of Jupiter’s interior and atmosphere. They’ll also continue their work at the laboratory in Marseilles to make the spinning table simulation more complex and more realistic.

One goal is to add a thin, stable layer of fluid on top of the spinning water, which would function like the thin outer layer of Jupiter’s atmosphere that’s responsible for the planet’s weather. The researchers believe this will help them simulate features like Jupiter’s famous Great Red Spot.

The research was funded by the National Science Foundation Geophysics Program, the French Agence Nationale pour la Recherche and the Aix-Marseille University Foundation.

The full article appeared in the UCLA Newsroom here: http://newsroom.ucla.edu/releases/ucla-geophysicist-models-jupiters-swirling-winds

 

 

 

 

January 20, 2017: 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.

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

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.

March 10 2017: 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

UCLA Meteorite Hunter Jason Utas In Finnish Magazine Tähdet Ja Avaruus

UCLA Meteorite Hunter and Graduate Student Jason Utas Appears In Finnish Magazine Tähdet Ja Avaruus
utas

Known for being a meteorite hunter extraordinaire, UCLA Earth, Planetary, and Space Sciences Graduate Student Jason Utas has appeared in the Finnish magazine Tähdet Ja Avaruus discussing meteorites. You may find some of the samples he has recovered or has put up at the UCLA Meteorite Museum which is FREE and open to the public in UCLA Geology Building, Room 3-697 open M-F 9AM-4PM and Sunday 1PM-4PM

You can download the article here: ta0716_meteoriitti

March 03 2017: 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 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.

February 17, 2017: 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.