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The Earth and Planets Laboratory hosts free weekly scientific seminars most Mondays and Thursdays. The popular seminar series covers the broad range of topics studied on our campus and are presented by both guest speakers and Carnegie scientists. 

Note: These seminars are designed for a scientific audience and have limited space, so we are not advertising the Zoom links publically. However, you're still welcome to join! Just email Alycia Alexander (adalexander@carnegiescience.edu) for information on how to attend. If you are employed by Carnegie Science you will receive an email reminder and Zoom link automatically. 

General Seminars

  • Monday, November 29, 2021, at 11:00 a.m.
    Ranga Dias, University of Rochester
    Title: Towards Ambient Superconductivity in Hydride-Based Materials
    Abstract: Superconductivity has been one of the profound quantum phases in condensed matter physics. Efforts to identify and develop room-temperature superconducting materials are an intensive area of research, motivated by both fundamental science and the prospects for applications. More than a century of rigorous research has led physicists to believe that the highest Tc that can be achieved is 40K for conventional superconductors. However, the recent discovery of superconductivity in hydrogen sulfide at 203K1 changed the notion of what might be possible for phonon–mediated superconductors. In this talk, I will discuss recent developments on high-pressure room temperature superconductivity.
    Host: Timothy Strobel
  • Monday, December 6, 2021, at 11:00 a.m.
    Michael Thorne, University of Utah
    Title: Global search for ultra-low velocity zones at the core-mantle boundary
    Abstract: Seismic heterogeneity in the deep mantle ranges in scale from 1,000’s of km as represented by the Large Low Velocity Provinces (LLVPs) and imaged in seismic tomography down to 10’s of km as imaged through the scattered seismic wavefield. The origin of the small-scale heterogeneities is still debated yet enigmatic features with scale lengths from 10’s to 100’s of km, and known as ultralow-velocity zones (ULVZs) likely contributes to a large portion of the observed heterogeneity. ULVZs have been known to exist for nearly three decades, although a precise definition of what constitutes a ULVZ is still lacking.  These features are primarily characterized by their low seismic velocities, reported as being decreased by as much as 45% for S-waves and 25% for P-waves with respect to standard 1-D reference Earth models.  ULVZs are typically best modeled as thin features on the order to 10 to 30 km in thickness, although some regions may exhibit greater thicknesses. ULVZ origins remains uncertain, as they have been discovered in a wide variety of settings, from directly underlying hot spot volcanoes and possibly representing the roots of whole mantle plumes, to accumulating near the boundaries of the Large Low-Velocity Provinces, to lying on the boundaries of regions of past subduction. Early interpretations focused on a partially molten origin as this could readily explain the ultra-reduced S-wave velocities. However, recent mineral physics efforts have demonstrated that compositional anomalies such as the Fe-enrichment of the mineral ferropericlase could also produce the required velocity decreases. Furthermore, the development of ULVZ material has also been proposed through many different mechanisms such as by melting of Mid-Ocean Ridge Basalt in down going slabs, through core-mantle reactions, or possibly through remnants of Earth’s early differentiation. Nonetheless, all features with low seismic velocities are collectively referred to as ULVZs and their makeup, compositional or partially molten, and origin could be due to a combination of all of these scenarios.
    In order to understand what these features physically represent, what they are, how they may have originated in the Earth, and what role they play in Earth evolution and dynamics we need to determine where these features exist and what their physical parameters are. Here we report on our efforts to globally map their locations and determine their physical properties using a combination of multiple seismic phases sensitive to the deepest layers of the Earth, 2- and 3-D seismic waveform modeling with the AxiSEM3D approach, and Bayesian inference. We present new maps of probable ULVZ existence covering more than 50% of the CMB by surface area.  We show that as much as 20% of the CMB area may contain ULVZs and that several mega-sized ULVZs with length scales on the order of 1,000 km may exist.  ULVZs are found in all regions of the deep mantle from within LLVPs to regions of inferred past subduction.  Furthermore, we show new details of the ULVZ beneath the Coral Sea and the Samoan mega-ULVZ, demonstrating it to be roughly 2× as large as presently thought and that it may contain a significant compositional component.
    Host: Lara Wagner

  • Monday, December 13, 2021, at 11:00 a.m.
    Ian CzekalaPenn State University
    Title: Opportunities for Imaging the Planet Forming Environment with ALMA
    Abstract: In recent years, spatially resolved observations of protoplanetary disks have delivered stunning images of radial substructures and azimuthal asymmetries, yielding new insights into the planet-forming environment. With its additional capability to spectrally resolve molecular line emission, the Atacama Large Millimeter Array (ALMA) is providing an exciting new dimension with which to study protoplanetary disk dynamics, structures, and astrochemical inventories. In the first part of this talk, we will describe how we use the bulk Keplerian motion of protoplanetary disks to precisely (<5%) constrain the central stellar mass, and, when combined with stellar orbits, how these constraints can unlock the architectures of multiple-star protoplanetary systems. We will discuss our survey of 20 circumbinary systems in the context of the dozen Kepler circumbinary (or "Tatooine") planets, its implications for a coplanar planet/disk population around short-period binaries (periods < 40 days), and the possibility of a set of widely dispersed orbits around wider binary systems (periods > months). Next, we will describe how our advances in Hamiltonian Monte Carlo techniques for high dimensional Bayesian inference (as is necessary for multi-instrument orbital datasets) have enabled us to infer the architecture of the nearby, triple mid-M dwarf system TWA 3, whose circumbinary protoplanetary disk lies in a "transition region" between the coplanar and dispersed populations. In the final section of the talk, I will highlight the upcoming results from the Molecules with ALMA at Planet-forming Scales (MAPS) ALMA Large Program ("The Chemistry of Planet Formation") and identify opportunities to use molecular emission to search for (proto)-planetary kinematic signatures. Central to these efforts are robust, non-parametric imaging methodologies, broadly categorized under the umbrella of "Regularized Maximum Likelihood" (RML) techniques. We will conclude with preliminary results from our open-source "Million Points of Light" RML framework and sketch out potential high-fidelity imaging workflows for ALMA continuum and spectral line datasets.
    Host: Alycia Weinberger

  • Monday, December 20, 2021, at 11:00 a.m.
    Munazza Alam, Earth and Planets Laboratory
    Title: Characterizing Giant Planet Atmospheres with Hubble
    Abstract: With over 4,000 exoplanet discoveries to date, we have caught a glimpse of the broad diversity of planets that span a range of masses, compositions, and orbital configurations. The next chapter in exoplanet exploration will focus on probing the atmospheres of these worlds, and we are now poised to begin large-scale atmospheric studies of exoplanets with current instruments on the Hubble Space Telescope (HST) via transmission spectroscopy. In this talk, I will present precise optical to infrared (~0.3-5.0 microns) transmission spectra taken with HST for four gas giant planets: WASP-52b, HAT-P-32b, WASP-62b, and HIP41378f. I compare the transmission spectra of these planets to a grid of 1D radiative-convective forward models and retrieve the planetary atmospheric properties. Expanding efforts for comparative exoplanetology, these optical to infrared observations constrain the atmospheric and chemical compositions of the most favorable targets well-suited for follow-up with JWST.
    Host: Johanna Teske

  • Monday, December 20, 2021, at 11:00 a.m.
    Yan Zhan, Earth and Planets Laboratory
    Title: Modeling Volcano Breathing: A way to forecast eruptions 
    Abstract: Before most volcanic eruptions, restless behaviors, such as gas emission, surface deformation, temperature changes, and earthquakes, can be observed. It is essential to quantify the subsurface processes leading to the volcanic eruptions. Therefore, we will be able to combine monitoring data and numerical models to forecast eruptions like weather forecasts. In this talk, Yan will show a case study that used a thermo-mechanical model to explain the multiple precursory signals observed before the 2006 explosive eruption of Augustine volcano, Alaska. You will also learn many similarities between a volcano and an espresso maker. The models will show how to build high pressure to trigger eruptions or to create crema in espresso.
    HostHélène Le Mével

View Past Seminars:

We record and publish most seminars on our YouTube Channel.