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1 | CIPS - Planetary Science SEMINARS - Fall 2024 | |||||||
2 | Campus and bay-area speakers will present in person. Remote speakers will present over Zoom. | |||||||
3 | Wednesdays 1:10-2:00 PM. In-person talks will be in 131 Campbell Hall. Typically we will provide a simple lunch from 12:45-1:05 | |||||||
4 | For a Zoom link to the meeting please contact: militzer @ berkeley . edu | |||||||
5 | Recordings from past presentations can be found here: https://drive.google.com/drive/folders/1it7b0Z_QRXCAktz-szIShkR1-2L0oO72?usp=sharing | |||||||
6 | Date | Speaker | Zoom/In person | Affiliation | Title | Abstract | Host | |
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8 | 28-Aug | Phil Marcus | In person | UCB Engineering | 3D Models and Solutions to the Equations of Motion of Jupiter's Great Red Spot | Ever since the Voyager fly-bys in the late 1970’s, there have been models and 2D numerical simulations of the Great Red Spot (GRS). Although much has been learned from these studies about vortices embedded in east-west, zone-belt flows, it has never been clear how much of the physics in these studies is applicable to the 3D, stratified and convective Jovian atmosphere. (After all, in 2D, the patterns of a flow’s streamlines are extremely limited in their possible appearances and always tend to look like vortices in zonal flows – just like the grain and knot-hole patterns in a piece of plywood.) Here, we present well-resolved solutions to the equations of motion in a realistic Jovian atmosphere (equivalent to 6000 X 6000 X 6000 finite difference points). We also present a simple analytic model based on the solutions that explain most features of the numerical solutions. The solutions to the equations of motion are not unique, and we found that a wide range of vortices with different strengths, vertical thicknesses, and depths, and with different heights of the Jovian convection zone can quantitatively reproduce Hubble Space Telescope (HST) observations of the GRS wind field, including the fact that its center is quiet with almost no vorticity. However, when the solutions are also constrained to agree with recent temperature observations from the James Webb Space Telescope (JWST), the possible range of stable vortices that agree with the HST winds are severely reduced, and in fact, are nearly unique. The calculations give extremely specific heights for the bottom, top, and middle of the Great Red Spot with little freedom for changes in these heights without the simulation becoming unstable or differing qualitatively from the temperature observations. Although our numerical simulation was constrained to agree with the observations of the HST winds and the JWST temperatures, it also agrees with winds measured by JWST, and the temperatures and gravity anomaly observed by Juno, which measure dynamics in the lower part of the GRS. | Phil Marcus | |
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10 | 4-Sep | June Wicks | In person | John Hopkins | Thermodynamic and dynamic measurements of planet-forming materials at the extremes of pressure and temperature | Recent advances in laser technology and diagnostics has enabled experimental access to unprecedented pressures and temperatures. How do these experiments, lasting a matter of nanoseconds, inform the phase diagram of minerals in planetary interiors? In this seminar, I’ll focus on MgO, one of the building blocks of rocky mantles, and describe different experiments that give insight into the kinetics of phase transformation and melting. By utilizing decaying shocks, steady shocks, and varying crystallographic orientation, we can probe at the shock front or behind the shock front, or access different phase assemblages. I’ll also describe novel experiments to measure the viscosity of MgO, which is expected to drop by two orders of magnitude across the B1-B2 phase boundary. Deformation of MgO may control mantle convection of super-earths and other large rocky planets, and dynamic experiments may inform the next generation of exoplanetary interior models. | Victor Naden Robinson | |
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12 | 11-Sep | Mei-Yun Lin | in person | SSL | Heavy Ion Outflow in the Earth-Moon System | The discovery of magnetospheric heavy ions in the 1970s led to a widespread belief that low-charge state heavy ions in Earth’s magnetosphere must originate from Earth’s ionosphere, although this may not be the case for all species. Oxygen ions, the dominant species in the magnetosphere, are primarily sourced from Earth’s atmosphere through chemical reactions or photoionization. Metallic ions, on the other hand, are mostly deposited in Earth’s atmosphere from the ablation of meteoroids. In addition to their terrestrial origin, both oxygen and metallic ions can also be created from the ionization of the lunar exosphere, making them common species in the lunar pickup ions. This presentation compares the production and transport of heavy ion outflow by various species within Earth’s magnetosphere. Different strategies are developed to evaluate the contributions of heavy ions from the ionosphere and the Moon across different solar and geomagnetic conditions. The Polar Wind Outflow Model (PWOM), a physics-based model solving the transport of ionospheric outflow, is adopted to estimate the ionospheric contribution. On the other hand, in-situ THEMIS-ARTEMIS observations of ion and electron fluxes are utilized to properly calculate the ionization rates of the lunar-originating ions when the Moon passes through the upstream solar wind, magnetosheath, and magnetotail. The simulation results suggest that the ionosphere is the primary source of heavy ions to the magnetospheric plasma. However, the supply of heavy ions from the ionosphere differs by species and is regulated by the timescale of production and loss at lower altitudes, as well as the composition of the ionospheric plasma. Conversely, the lunar pickup ions are quite consistent within the cis-lunar environment, except when the Moon is passing within Earth’s magnetosphere. Consequently, certain ion species, such as metallic ions, are predominantly produced by the lunar source rather than the ionosphere. This research provides a deeper understanding of the complex interactions between the Moon, solar wind, and Earth's magnetosphere, which could offer insights into the atmospheric evolution of the Earth-Moon system. | Phil Marcus | |
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14 | 18-Sep | Murti Nauth & Melissa Marquette | 20 minutes each; in person | SSL and EPS | Energized Electrons in the Martian Magnetotail & Building more robust models of the Martian nightside ionosphere | Energized Electrons in the Martian Magnetotail The Sun's magnetic field creates a flared wake behind Mars when it drapes about the planet, and this region is called the "magnetotail." When solar wind electrons enter this region, they can become energized by various plasma processes. These electrons can precipitate towards Mars and lead to auroral emissions. But, the exact mechanisms that energize these electrons is not fully understood. We are unraveling the mysteries of Martian aurora, and the electron dynamics at play are a key piece of this puzzle. Our previous work analyzed a case study which constrained one electron acceleration mechanism, and now we've built upon this by analyzing 10 years of MAVEN data to statistically determine these mechanisms. Building more robust models of the Martian nightside ionosphere Electron impact ionization is the most significant source of ionization in the nightside ionosphere of Mars. However, up until recently, it had not been characterized sufficiently well to enable its incorporation as an ionization source in Martian Global Ionosphere-Thermosphere Models (GITMs). With the MAVEN mission's 10 years (hooray!) of observations at Mars, we have sufficient data to build an empirical model characterizing electron impact ionization on the nightside. This empirical model has in turn been incorporated into state of the art GITMs, resulting in more realistic ionospheric simulations. | Paul Szabo | |
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16 | 25-Sep | Michael Manga | in person | UCB EPS | Water in the Martian subsurface | Large volumes of liquid water transiently existed on the surface of Mars more than 3 billion years ago. Much of this water is hypothesized to have been sequestered in the subsurface or lost to space. We use rock physics models and Bayesian inversion to identify combinations of lithology, liquid water saturation, porosity, and pore shape consistent with the constrained mid-crust (∼11.5 to 20 km depths) seismic velocities and gravity near the InSight lander. A mid-crust composed of fractured igneous rocks saturated with liquid water best explains the existing data. Our results have implications for understanding Mars’ water cycle, determining the fates of past surface water, searching for past or extant life, and assessing in situ resource utilization for future missions. | ||
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18 | 2-Oct | Loren Matilsky | in person | UCSC | The role of non-axisymmetric dynamo magnetic fields in solar tachocline confinement | In the solar interior, strong latitudinal differential rotation persists throughout most of the convection zone (CZ). At the base of the CZ, this differential rotation transitions across a narrow layer (called the "tachocline") to solid-body rotation in the stably stratified radiative zone (RZ) below. The dynamical confinement of the tachocline against diffusive spread is a long-standing, still unsolved issue in stellar astrophysics. In 2022, we explored a 3-D MHD simulation of a CZ-RZ system in which the nonaxisymmetric magnetic field from a dynamo was self-excited in the CZ, spread into the RZ, and confined a tachocline via magnetic torque. We have more recently shown that a skin effect well describes the amplitude of poloidal field strength in the RZ for several CZ-RZ dynamo simulations at different magnetic Prandtl numbers, even when the cycle is aperiodic. Our results suggest that the solar tachocline can be confined by the nonaxisymmetric and aperiodic modes of the solar cycle, with each frequency of the dynamo separately penetrating to its own skin-depth. Furthermore, any component of a nonaxisymmetric field corotating with the solid-body RZ should penetrate far deeper than any skin depth. We thus argue for an additional source of magnetic field deep below the CZ (in addition to a primordial remnant) that could confine the tachocline. | Phil Marcus | |
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20 | 9-Oct | No Seminar (DPS conf.) | Phil Marcus | |||||
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22 | 16-Oct | No Seminar (BAPS Conf.) | ||||||
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24 | 23-Oct | Mohammad Farhat | in person | UCB | The dynamical history of the Earth-Moon system: a Telltale of a Tidal Waltz | Ever-since the Moon formed close to the Earth, it has been forced by tidal interactions to drift away through orbital angular momentum pumping, depleting the Earth’s rotational angular momentum budget. Consequently, the evolving Earth-Moon dynamics, over geological timescales, have impacted the Earth’s past climate, leaving behind archival traces in the geological strata. Interestingly, proxies in these strata are used as an observatory to provide snapshots of the history of the lunar orbit and the Earth’s rotation, the earliest registered to-date at ~3.2 billion years ago! However, a complete theoretical reconstruction of the lunar orbit, which traces its evolution from the present state to a post-impact nosy neighbor some 4.5 billion years ago was yet to be established. The latter presents a 60-year old problem in astronomy known as the “timescale problem of the Lunar origin”. In this talk, I will delve into the rich dynamical history of the Earth-Moon system, bridging between fluid mechanics in the Earth’s paleo-oceans, atmospheric dynamics, the orbital and rotational dynamics of the Earth-Moon system, and the climatic and geological impact of the evolving system; all coming together to solve the 60-year old paradox; while unraveling, perhaps as expected, more challenging ones. | Mei-Yun Lin / Paul Szabo | |
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26 | 30-Oct | John Brewer | in person | San Francisco State University | Planetary System Architectures: How Rare is the Solar System? | The Solar System seemed like the ideal primer on planet formation; widely spaced planets with rocky (refractory) planets close to the star and more massive gas giants (volatiles) further out. The first exoplanet discovery clearly demonstrated that things would not always be straight forward. Nearly 6,000 planetary systems have been discovered in the past few decades, with almost 1,000 of those having more than one detected planet. To date none of them look like the Solar System. The most common type of planet we have found is not present around the Sun and most multi-planet systems are tightly packed, close to the star, with little variation in size. A new class of extreme precision radial velocity (EPRV) instruments are pushing to detect lower mass planets at longer period orbits. The EXtreme PREcision Spectrometer (EXPRES) is one such instrument and the EXPRES 100 Earths Survey now has almost five years of EPRV data. I will present some early results and discuss some of the challenges that still lie ahead. | J. J. Zanazzi | |
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28 | 6-Nov | Robert Lillis | in person | SSL at UCB | Serpents in the Night: Mars' Enigmatic Electron Aurora | Electron aurorae are an intrinsic feature of the Martian nightside upper atmosphere and unique hybrid magnetosphere. They occur in regions where the crustal magnetic fields are very weak and/or vertical and where Mars' magnetotail topology connects the atmosphere to sources of suprathermal electrons, which cascade into the upper atmosphere, causing UV emission. First detected in 2005 and through subsequent sporadic detections by the Mars Express and MAVEN spacecraft over the following 16 years, our understanding of these has grown exponentially since 2021 when the Emirates Mars Mission began making whole-disk observations of Mars in the Far ultraviolet, showing that that FUV electron auroral emission is a) primarily from oxygen at 130.4 nm and 135.6 nm and b) observed in a range of morphologies. Crustal field aurora and enigmatic 'sinuous' aurora have well-defined edges, while most emission away from strong crustal fields is fainter and 'patchy' with less-defined edges. This presentation will review the current state of understanding of Mars electron aurora and point to future investigations. | Phil Marcus | |
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30 | 13-Nov | Anna Milillo | Virtual | Institute of Space Astrophysics and Planetology (IAPS), INAF, Rome, Italy | Mercury’s environment observed by BepiColombo mission and SERENA experiment | Mercury’s environment is a complex system where the magnetosphere, the exosphere and the surface are inherently coupled and interact with the interplanetary medium that is particularly extreme for its close proximity to the Sun. Mercury lacks a thick atmosphere, and it possesses a weak internal magnetic field which is not able to effectively shield the planet. Previous explorations of this innermost planet include Mariner 10 and the NASA’s MESSENGER mission. Ground-based observations allowed to observe few exospheric elements. Now we know that Mercury’s environment is highly dynamic. The magnetosphere can be fully reconfigured in a few minutes, and the exosphere shows a variability down to 10s minutes. But the new results have opened new unsolved questions about the functioning of this dynamic system, how the magnetosphere responds to the solar activity, and how the exosphere is connected to the surface and to the magnetosphere. For discriminating between space-time variations and for investigating the effects of external drivers to the planet, two spacecraft are needed. BepiColombo ESA-JAXA mission is en route to Mercury. Two spacecraft will be inserted in orbits around the planet, MPO-Mercury Planetary Orbiter and Mio-Mercury Magnetospheric Orbiter, respectively. BepiColombo includes a comprehensive payload for the investigation of the environment, the surface and the interior of the planet; moreover, it includes fundamental physics experiments. SERENA particle package on board MPO is a key experiment since it links the observations of near-planet particles both at the surface and at the magnetosphere. During the cruise phase, SERENA ion sensors, PICAM and MIPA, have collected interesting measurements during the swing-bys at Mercury. The BepiColombo orbit insertion will be performed in November 2026, and the scientific operations will start in 2027. We expect many fantastic results after this very long journey! | Mei-Yun Lin | |
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32 | 20-Nov | Patrice Le Gal | Cancelled | IRPHE CNRS U Marseille | Phil Marcus | |||
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34 | 27-Nov | No seminar | ||||||
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36 | 4-Dec | Arcelia Hermosillo Ruiz | in person | University of California, Santa Cruz | Constraining Dynamical Processes in the Outer Solar System and the AU Mic Debris Disk | Orbital distributions of the small bodies in debris disks (dust/planetesimal belts left over from planet formation) provide important information regarding the dynamical history of a planetary system. In our solar system, Transneptunian populations–particularly those in mean motion resonance with Neptune–hint towards an early chaotic planetary migration. In extrasolar systems, dust structure hints at the presence of undetected planets and various dynamical processes. It remains an open question if the planet architecture of a system is predestined from the initial star and protoplanetary disk or if the gravitational interactions between planets and planetesimals during the “teenage” years of a system are the determining factor. Motivated by this question, I will discuss work in constraining the evolution of the outer solar system and understanding planet-disk interactions in the AU Mic debris disk. First, I will present published and ongoing work in constraining the migration of the giant planets in our solar system due to planetesimal-driven migration and an upheaval such as the “Nice Model.” Recent well-characterized surveys made this work possible, providing a method to make strong statistical comparisons between Nbody simulations and observations. The upcoming Vera Rubin Observatory’s LSST will observe ~10 times more objects for the outer solar system, making this an exciting time to be doing this work. Lastly, I will show how an inclined, eccentric planet perturbs dust from an exterior debris disk to create dust clouds ejected primarily from one side of the disk. My Nbody simulations produce similar structure as seen in the scattered light images of the AU Mic debris disk. This system provides a unique opportunity to observe time-evolving morphology at yearly timescales. | J. J. Zanazzi | |
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38 | 11-Dec | No seminar - AGU | ||||||
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