CIPS Seminar Fall 2018 (public)
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CIPS SEMINARS - Fall 2018
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131 Campbell Hall
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Wednesdays 13:00-14:00 PM
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DateSpeakerAffiliationTitleAbstractHost
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22-AugFirst Instructional Day
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29-AugSteve BrysonNASA AmesGrasping for eta-Earth: Kepler Occurrence Rates Near the Detection LimitEta-Earth, the occurrence rate of terrestrial planets in the habitable zone, is a parameter of broad interest as well as a critical input to the design of future efforts to characterize habitable exoplanets. NASA’s Kepler Space Telescope spent 4 years obtaining high-precision photometry on ~150,000 Sun-like stars to measure exoplanet occurrence rates, with particular focus on Earth-size planets in the habitable zone. With 2,327 confirmed/validated planets and 2,244 planet candidates, Kepler has enabled high-confidence estimates of exoplanet demographics across a wide range of planet sizes and orbital periods. But high-quality statistics describing Earth-size planets in the habitable zone around Sun-like stars has remained elusive, with Kepler-based occurrence rate estimates for such planets spanning two orders of magnitude in the literature. This uncertainty is primarily due to this population of planets being at the Kepler detection limit, where planet-imitating stellar phenomena and instrumental systematics pollute the data. We will discuss how occurrence rates are derived from Kepler data, focusing on the challenge of reliably identifying true planet statistics from this polluted data. We will discuss individual planet and population-based strategies, with a focus on unsolved problems. These challenges must be met because, for the foreseeable future, Kepler data is the only data that can reveal the statistics of Earth-like planets in the habitable zones of Sun-like stars.Courtney Dressing
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5-SeptMatthew PennyOhio State UniversityThe Whole Iceberg: Completing the Census of Exoplanets with the WFIRST Microlensing SurveyThe Wide Field Infrared Survey Telescope (WFIRST) will be NASA's next flagship mission to follow James Webb. Roughly a quarter of WFIRST's primary mission will be spent conducting an exoplanet microlensing survey. The survey will provide a statistical assay of the cold exoplanet population with masses greater than that of Mars and orbits beyond ~1 AU, with a total planet yield comparable to Kepler's. It will also measure the mass function of free-floating planets potentially down into the mass regime of large Kuiper Belt Objects. The WFIRST microlensing survey parameter space spans critical mass and distance scales in planet formation theories, including the ice line, the isolation mass, and the critical mass for runaway gas accretion. After a brief introduction to the microlensing technique I will give an overview of the WFIRST microlensing survey, highlights of its expected results, and introduce various ongoing efforts to ensure its success. I will also describe the legacy value of the WFIRST microlensing data set of high-cadence near-infrared lightcurves of ~200 million stars, which will be useful for guest investigators interested in topics as varied asteroseismology, astrometry, Galactic structure, warm transiting planets, and stellar-mass black holes.Megan Ansdell
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12-SeptJean-Baptiste RuffioKIPAC, Stanford UniversityThe GPI exoplanet survey and statistical tools for exoplanet detection.The Gemini Planet Imager (GPI) is a high-contrast exoplanet imaging instrument mounted on Gemini South, which is equipped with an extreme adaptive optics, a coronograph and an integral field spectrograph. In the past four years, the GPI exoplanets survey (GPIES) has observed more than 500 nearby young stars to search for young massive exoplanets and debris disks. In order to handle the large amount of data, we developed an automated architecture to process observations in real time as well as sophisticated planet detection algorithm based on matched-filtering. First, we will summarize the main results of the campaign. Then, we will present the data processing and planet detection framework required to derive new planet occurence rates for directly imagined planet. To finish, we will discuss the use of Bayesian analysis in the context of non-detections.Becky Jensen-Clem
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19-SeptTom EspositoUC BerkeleyDebris Disks in Scattered Light from the Gemini Planet Imager Exoplanet SurveyI will summarize discoveries and results from our circumstellar debris disk imaging campaign with the Gemini Planet Imager (GPI). This large, uniform survey uses polarimetry and spectroscopy to detect dust-scattered, near-IR light and has produced 27 disk detections out of 83 nearby young stars observed since 2013. For the first time for many of these planetary systems we are probing the ~10--200 au range with spatial resolutions of a few au; regions fundamental to planet formation. We will show images of the GPIES disks, including several for which we achieved the first scattered-light and/or polarized intensity detections. We will also discuss preliminary findings about the bulk properties of our debris disk sample and implications of our observational sensitivity to scattered-light disks for future imaging missions.Megan Ansdell
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26-SeptJustin CreppNotre DameUltra-precise Spectrographs that Operate at the Diffraction Limit The Doppler radial velocity (RV) method continues to inform our understanding of extrasolar planet formation and evolution, orbital architectures, masses and composition, and demographics. Although much progress has been made in generating precise RV time series measurements, basic physics considerations related to the way that spectrographs are designed and built can limit the utility of Doppler observations much below one meter per second. As a result, effects involving stability, image quality and spectral resolution, and consequently the handling of stellar activity, currently preclude the study of Earth-mass analogues orbiting Sun-like stars. In this talk, I will describe a new type of spectrograph that uses “extreme” adaptive optics to inject starlight directly into single mode fibers. By correcting for the image-blurring effects introduced by Earth’s turbulent atmosphere, I will argue that a diffraction-limited instrument should be capable of generating unprecedented RV precision. We are constructing the first-such spectrograph of this kind for the Large Binocular Telescope in Arizona. The instrument, named “iLocater,” will benefit from input images that achieve ~20 times higher spatial resolution than seeing-limited designs, enabling high spectral resolution (R=200,000) observations using an ultra-stable, compact optical design at low cost. With any time remaining, I will explain why the vector nature of light must be considered when building diffraction-limited precision RV instruments. Megan Ansdell
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3-OctMarta Bryan51 Peg Fellow, UC BerkeleyThe Celestial Movers and Shakers: Gas Giants as Tracers of Planet FormationOver the past two decades thousands of planets with an extraordinary diversity of properties have been discovered orbiting nearby stars. Many of these exoplanetary systems challenge our narrative for how planets form and evolve, motivating the search for observational clues to the underlying mechanisms that led to this diversity. In this quest, gas giant analogs to Jupiter and Saturn immediately stand out as the most visible relics of the planet formation process. They are first and foremost a product of their birth environment, with properties that are shaped by divergent disk and host star properties. They also actively shape their surroundings, from altering the structure of the gas disk from which additional planetary bodies may coalesce, to pushing smaller planets around, causing them to migrate or even ejecting them from the system. Thus, to explain the observed diversity of exoplanet systems, we must first understand how gas giant planets form and evolve. In this talk I will describe my work using radial velocity, direct imaging, and high-resolution spectroscopy techniques to explore the impact of outer gas giant planets on inner exoplanet systems, and to probe the origins of super-massive gas giant planets at wide separations. Becky Jensen-Clem
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10-OctJeffrey FungSagan Fellow, UC BerkeleyThe Basics of Circumplanetary DisksPlanets forming in protoplanetary disks capture gas and form envelopes around themselves. Rotating envelopes are called cirumplanetary disks (CPDs). The flow structure and rotation speeds in CPDs directly impact the rates of gas and solid accretion of the planets; while the sizes and temperatures of CPDs determine their luminosities, and therefore the likelihood of detecting protoplanets in observations. Using hydrodynamic simulations of unprecedented resolutions, we produce measurements of CPDs as functions of planet mass under both isothermal and adiabatic conditions. We analyze their rotation speeds, flow patterns, and density structures. We find isothermal CPDs have rotationally supported disks at a size of about 5% of the planets’ Bondi radii, while adiabatic CPDs have rotation rates that approach Keplerian speed as planet mass increases. We will discuss applications of our findings in the context of pebble accretion, runaway gas accretion, and the formation of satellite systems.Ian Czekala
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17-OctBerkeley EPS (Ned Molter, Joshua Tollefson, Michael Wong et al.)UC Berkeley EPSTalk 1: Uranian Rings Probed with ALMA Observations

Talk2: Constraining Opacity Sources on Neptune with ALMA

Talk3: Superstorms on Jupiter: Convection, volatiles, clouds, and lightning near Juno's 4th orbit
A series of three 12-minute talks from members of the Berkeley EPS community. Imke de Pater
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24-OctJason SteffenUNLV, Associate ProfessorChallenging the prevailing assumptions in exoplanet researchI will present the results from three studies that investigate effects that are missed due to prevailing assumptions. The first is the assumption of coplanar systems when investigating dynamical instability in a planetary system. The second is the assumption of equally spaced planets and the proper definition of planet spacing and system compactness. The third is the assumption regarding the architecture of planetary systems when analyzing Doppler data. Each of these assumptions can produce an incorrect interpretation of the histories and properties of planetary systems. These results show that "compact" planetary systems are not as compact as believed and provide a better criteria for classifying these systems. They also show compelling evidence that a sizeable fraction of systems with a single, eccentric planet are in fact multiple planets near mean-motion resonance—implying a significant mischaracterization of these systems and their histories.Howard Isaacson
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31-OctDiogo L. LourençoUC DavisThe influence of melting on the thermo-chemical evolution of rocky planets' interiorsMelting has always been present throughout the history of the Earth, and especially early in its evolution. However, many unknowns still remain regarding its role in the dynamics of our planet. In this presentation I will show results that contribute to the developing understanding of the effects of melting on the thermo-chemical evolution of rocky bodies, with a special focus on the history of Earth. To achieve this, I performed numerical simulations of global mantle convection, and combine the numerical results with insights from scaling analysis to explore some fundamental aspects of the effects of melting on the thermo-chemical evolution of terrestrial bodies. I applied the models to investigate (i) how does melting-induced crustal production affects the interior state and surface behavior of an Earth-like planet, and (ii) the effects of intrusive versus extrusive magmatism on the surface tectonics and mantle cooling of a terrestrial planet.Robert Citron
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7-NovIan CzekalaHubble Fellow, UC BerkeleyThe Alignment of Binary Star Orbits and their Circumbinary DisksOne exciting legacy of the Kepler mission was the discovery of about a dozen transiting circumbinary (CB) planets, despite potential barriers to planet formation in these systems. Determining the CB planet occurrence rate, and thus the efficiency of CB planet formation, depends on assumptions about the sensitivity of Kepler to CB planets as a function of the mutual inclination between the binary and planetary orbits, since it is a key parameter in determining whether and how frequently CB planets transit. To contextualize the known CB planet population, we examine young and intermediate age binary stars that host circumbinary protoplanetary and debris disks and investigate trends in system architecture—namely mutual inclination—with binary orbital parameters. We forward-model new ALMA observations of the pre-main sequence spectroscopic binary UZ Tau E and its CB disk using carbon monoxide J=2-1 emission. UZ Tau E joins V4046 Sgr, DQ Tau, and AK Sco as the fourth system whose stellar orbit and disk parameters are well-known and a direct calculation of the apparent mutual inclination between the stellar and orbital planes is possible. We find that all of these systems, which host short-period (P < 30 days) binary stars, have apparent mutual inclinations less than 3 degrees. The architectural similarity between these systems and those Kepler systems hosting CB planets suggests that the mutual inclinations of planets around short-period binaries are intrinsically low, implying that there does not exist a large population of misaligned CB planets orbiting binaries with these periods. We further extend our analysis to include all known circumbinary disk systems in the literature. This expanded sample includes many longer period binary stars, but suffers from incomplete stellar orbits and/or spatially unresolved disk observations, resulting in significant uncertainty in solutions of system architectures. Given the existing data, however, there are already several longer period (P ≿ 30 days) systems for which coplanarity is highly disfavored, such as KH 15D, GW Ori, and TWA 3A. This suggests that whatever formation mechanism or evolutionary pathway that produced the shorter period binaries tends to bring the binary orbital plane and the CB disk into alignment, and that its influence wanes with increasing binary orbital period.Megan Ansdell
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14-NovArya UdryUNLV, Assistant ProfessorExploring martian magmatism: Understanding Mars' interior using martian meteoritesRovers and orbiters have allowed us to better understand Mars surficial and other geological processes. However, martian meteorites, which are our only samples from this planet, can help constraining magmatic processes that occurred on Mars. Although only 113 meteorites from Mars have been recovered, they have helped us unravel the martian crust and mantle using classic petrological analyses.Robert Lillis
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21-NovNon-Instructional Day
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28-NovHsien ShangASIAAChronology of the Very Early Solar System--What Do We Learn from Meteorites?Chondritic meteorites are treasures preserved from the early Solar System. They carry characteristic yet enigmatic features that puzzle the field of meteoritics for their origins. I will review some key facts about these primitive rocks, and how these facts can be and have been used as constraints for processes that produced them. These facts also serve as clues to the general star formation and evolution that helped shape our own past. Current state of the art for this interdisciplinary field will be briefly touched in various perspectives. Megan Ansdell
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5-DecDarryl SeligmanYaleOumuamua!I will review what is certain, what is speculative, and what is still completely mysterious about the first interstellar object observed to traverse the Solar System. The talk will delve into ‘Oumuamua’s origin, its unusual dynamics, and its physical properties. I will discuss the prospects for detecting additional such objects with LSST, as well as the prospects for in situ explo- ration of future interstellar visitors that are detected with sufficient advance warning.Megan Ansdell
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12-DecExam Week
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