Fall 2025 IfA Colloquia
Talks home
Date
Speaker
Affiliation
IfA Host
Title (click for abstract)
Aug 19 (Tu)
12:00pm
Abe Lerman
Exploratory Sciences
Habbal
Aug 29 (F)
12:30pm
Doug Finkbeiner
Harvard University
Liu
Sep 10 (W)
Thavisha Dharmawardena
NYU
Huber
Oct 8 (W)
Sara Mulas
INAF
Murtas
Oct 15 (W)
Branden Allen
UH SSEI
Hu
Oct 22 (W)
Ezequiel Treister
Universidad de Tarapacá
Sanders
Nov 17 (M)
11:30am
Kelly Fast
NASA PDCO
Simons
Nov 19 (W)
John Silverman
Kavli IPMU
Sanders
Talks are held at 11:45am HST in the IfA Mānoa Auditorium (C-214) unless otherwise noted.
For additional information, please contact Dr. Esther Hu.
An exploratory analysis of the Pan-STARRS data with AI interaction
Abe Lerman
CEO
Exploratory Sciences
Exploratory Sciences website
Extending some publicly available Pan-STARRS analysis to showcase a live dashboard that includes a computer vision model, driven by large-language model (LLM) prompting, and executed over AI Model Context Protocol (MCP).
Opening the Black Box: How We’re Learning to Read the Minds of AI Systems
Douglas Finkbeiner
Professor of Astronomy and of Physics
Harvard University
Website
Neural networks were once impenetrable black boxes, but interpretability research has transformed our understanding. A decade ago, researchers showed we could visualize how CNNs recognize images. Today’s language models at first seemed even more opaque, yet the last two years have brought remarkable breakthroughs—we can now identify specific “circuits,” watch models reason step-by-step, and edit their behavior in real-time.
These advances reveal both impressive capabilities and puzzling limitations. The same model may solve a complex physics problem one moment and then make an amateurish error the next. As AI systems increasingly assist with scientific research, understanding their reasoning (or how they mimic reasoning) becomes crucial.
I will describe the ongoing journey from black boxes to interpretable systems, showcasing recent mechanistic interpretability breakthroughs, and exploring what these “AI minds” reveal about physics reasoning. We’ll conclude with speculation about how AI systems may be used in coming years.
Understanding the origin of metals in giant planets
Yayaati Chachan
Postdoctoral Researcher
UC Santa Cruz
Website
The rate at which giant planets accumulate dust and gas is a critical component of planet formation models, yet it is extremely challenging to predict from first principles. Characterizing the metal content of giant planets provides important clues about their provenance. In this talk, I will describe my observational and modeling efforts to measure the abundance of metals in the interiors and atmospheres of extrasolar giant planets. First, using thermal evolution models, I quantify the bulk metallicity of nearly 150 transiting giant planets. This work reveals key insights into how giant planets assemble and explicitly shows that metals are preferentially accreted during the gas accretion phase. Next, I introduce a framework that links the atmospheric composition of giant planets to the nature of the solids and gas they accrete. By measuring the abundance of both refractory, e.g., silicon, iron, and volatile, carbon, oxygen, species, we can infer each planet’s solid-to-gas accretion ratio, likely accretion location, and the degree of thermal processing of the accreted solids. I will show how this framework is enabling us to make important strides in connecting giant planet composition and formation history at the population level. I will conclude with modeling work that explores the insights that carbon isotopic ratios can offer into the origin of directly imaged giant planets.
A 6D Multiscale Multiresolution view of the Milky Way and its Star Formation
Thavisha Dharmawardena
NASA Hubble Fellow
New York University
Website
The detailed 3D distributions of dust density and extinction in the Milky Way have long been sought after. However, such 3D reconstruction from sparse data is non-trivial, but is essential to understanding the properties of star-formation, large-scale dynamics and structure of our Galaxy. In this work I will introduce our new fast and scalable algorithm for 3D dust modeling. Using advanced ML methods such as sparse Gaussian Processes and Variational Inference, our algorithm maps the Solar Neighbourhood with millions of input sources in parsec scales within short timescales. Using this approach we map the inner 3 kpc of the Solar Neighbourhood down to 1 pc resolution. We identify large-scale structures in the Galaxy and its Molecular clouds, while simultaneously peering into individual molecular clouds. I will also introduce our ongoing work to understand the structure and formation scenarios of the bubbles, cavities and voids taking into account not just the dense structures in the Milky Way but also these large gaps driven by star formation and Galactic dynamics. I will introduce our newly discovered Eos molecular cloud which is the nearest molecular cloud to earth discovered for the first time in UV fluorescence. The Eos cloud consists of 98% CO-dark gas, providing evidence for the missing mass needed to fuel star formation, as theory predicts over 50% of the total mass required remains unobserved.
From Italy to Antarctica: single-dish solar imaging at high radio frequencies with the SunDish & Solaris Projects
Sara Mulas
Postdoctoral Researcher
INAF – Osservatorio Astronomico di Cagliari
Mapping the brightness temperature of the solar atmosphere at high radio frequency (>1 GHz) reveals incoherent free-free emission originating primarily from plasma processes in the local thermodynamic equilibrium, with the addition of sporadic gyromagnetic emission. These relatively simple processes, compared to other frequencies, provide a probe of physical conditions and vertical structure of the Chromosphere up to the Transition Region and the Corona.
The SunDish Project is devoted to solar radio imaging and monitoring the brightness temperature of the solar atmosphere in the radio K band (18-26 GHz) with the Sardinia (64-m) and Medicina (32-m) radio telescopes. These observations represent an effective tool to characterise the vertical structure and physical conditions of the solar Chromosphere both for quiet and active regions during their evolution at different phases of the solar cycle. The Solaris Project is a scientific and technological project devoted to the development of a Solar monitoring system in the radio W-band (70-120 GHz). It combines the implementation of dedicated and interchangeable high-frequency receivers on existing small single-dish radio telescope systems (1.5/2.6-m class) available in our laboratories and in Antarctica, to be adapted for Solar observations.
This extended network can complement other existing ground-based and space-based facilities aimed at the direct monitoring of the solar atmosphere both for Heliophysics science and Space Weather awareness.
University of Hawaiʻi Space Science and Engineering Initiative (SSEI) 13.5-Month Status and Activities
Branden Allen
Engineering Specialist Faculty
-and-
Program Lead, SSEI
University of Hawaiʻi Space Science and Engineering Initiative (SSEI)
The Space Science and Engineering Initiative (SSEI) was created as a joint effort between the UHM College of Engineering (CoE) and the Institute for Astronomy (IfA) for the establishment of a multi-island advanced technology research and development center based in Hilo, which aims to significantly expand technical capabilities to support the space sciences, particularly targeting application for the observatories on Maunakea and Haleakalā and for competitive participation and leadership in future spaceflight opportunities.
Simultaneously, and in collaboration with the UHH College of Health and Natural Sciences (CHNS), the SSEI has established and launched a pre-engineering program to extend engineering education opportunities to residents of the Big Island and establish an education pipeline to build local talent and, ultimately, new career opportunities.
Here, I will discuss the current status of the SSEI and give a brief overview of our current portfolio of activities.
Feeding and Finding Close-Separation Dual AGN: Insights from Multiwavelength SEDs and ALMA Observations
Ezequiel Treister
Professor
Universidad de Tarapacá
Understanding dual active galactic nuclei (AGN) at small nuclear separations (1-10 kpc) is crucial for tracing supermassive black hole growth in major galaxy mergers, yet extreme obscuration (NH > 10²⁴ cm⁻²) makes these systems challenging to identify and characterize. In this talk, I will present a comprehensive multiwavelength study addressing both aspects.
Using SED fitting from hard X-rays to the far-infrared for 72 AGN in mergers, I will show that morphologically-determined merger stage—not projected separation—drives enhanced AGN activity and star formation, with late-stage mergers exhibiting 2-5 times higher values. High-resolution ALMA ¹²CO observations reveal that nuclear molecular gas content is similar between single and dual AGN hosts, suggesting that dual AGN occurrence depends on variability and obscuration rather than gas availability.
This motivates the key question: how do we find heavily obscured dual AGN? I will demonstrate that ALMA continuum observations at ~200 GHz, combined with hard X-ray data, provide a powerful detection method. The millimeter-X-ray luminosity correlation effectively identifies Compton-thick AGN and applies to dual AGN systems, opening a new avenue for expanding the census of close-separation dual supermassive black holes in late-stage mergers.
Status and Future of The James Clerk Maxwell Telescope
Geoffrey Bower
Director
James Clerk Maxwell Telescope (JCMT)
-and-
President
East Asian Observatory (EAO)
I will summarize the current status and future plans for the world’s largest sub millimeter telescope, the JCMT. The JCMT provides a powerful suite of instruments for wide-field mapping, heterodyne spectroscopy, and very long baseline interferometry. These have been used extensively and with high impact including the discovery and characterization of sub millimeter galaxies, studies of star-formation and galaxy evolution, and the first images of the black holes in M87 and Sgr A* with the Event Horizon Telescope. New observing programs in the areas of VLBI, time domain science, and intensity mapping will play key roles in the future of the JCMT and new instrumentation will lead to order of magnitude improvements in capability.
Orbital evolution in the outskirts of planetary systems
Sam Hadden
Postdoctoral Fellow
Canadian Institute for Theoretical Astrophysics
Website
Exoplanet discoveries over the past three decades have revealed an astonishing diversity of planetary systems. While significant strides have been made in understanding the population of close-in planets that dominate survey discoveries to date, we do not have a firm grasp of what other systems look like at wider separations, where our own solar system planets reside. This will change in the near future when NASA’s Roman mission undertakes a micro-lensing census of the low-mass planet population beyond ∼1 AU. In this talk, I will describe how planetary dynamics theory can be applied to interpret micro-lensing planet detections. In particular, dynamics theory can link together the population statistics of bound and free-floating planets to give a comprehensive picture of how orbital evolution shapes the outer regions of planetary systems. Applied to the current results of ground-based micro-lensing surveys, I will show that this theory predicts a substantial population of “detached” Neptune-sized planets orbiting at hundreds of AU on highly eccentric orbits. I will also discuss prospects for better understanding the past orbital evolution of our own outer planets with Rubin LSST set to deliver over an order of magnitude increase in the number of known outer solar system small bodies.
A New Hot Jupiter Census from NASA’s TESS Mission
Sam Yee
51 Pegasi b Postdoctoral Fellow
UCLA
Website
Hot Jupiters — giant planets on short-period (< 10 days) orbits around their host stars — represent the most extreme outcome of planet formation. Even though they were the first type of exoplanet around Sun-like stars to be discovered, their origins remain unclear. One challenge is our limited understanding of hot Jupiter statistics, as most of them were discovered by a heterogeneous collection of ground-based surveys with a variety of biases. NASA’s Transiting Exoplanet Survey Satellite (TESS), a uniform all-sky transit search, presents the opportunity to revolutionize hot Jupiter demographics by unifying these previous planet searches. Over the past few years, I led the TESS Grand Unified Hot Jupiter Survey to confirm and characterize hundreds of planet candidates from TESS with facilities like Keck and Magellan. I will present the 4-sigma detection of a pile-up in the period distribution, the dependence of hot Jupiter occurrence on host star properties, and new evidence that they are found around a kinematically young galactic population. I will also discuss how our survey is enabling new lines of inquiry including the discovery of giant planets in the galactic thick disk, as well as detailed characterization of benchmark systems to test key physical processes like tidal inflation and orbital decay.
A new era for astrobiology studies with JWST
Sara Faggi
Research Assistant Professor
American University
NASA Bio
The importance of studying water and organic molecules in space is related to their astrobiological relevance. The origin of water and pre-biotic organic molecules on Earth is a complex research subject, as well as the search for habitable environments outside Earth, and both are driven by the need for understanding the conditions required for life to emerge. Did the delivery of exogenous organics and water by proto-planetesimals enable the emergence of life on Earth? Do ocean worlds in the outer solar system harbor habitable conditions? This talk will address these studies through spectroscopic investigations of Centaur 29P/Schwassmann-Wachmann 1, and icy moons Enceladus and Europa, with the exquisite sensitivity of JWST.
Investigations of Centaur 29P enabled the exploration of primitive ices from a dynamical class of small bodies that may have a formation history in the protoplanetary disk distinct from that of long-period comets and yet have not suffered the thermal processing experienced by short-period comets. JWST observations uncovered complex heterogenic molecular spatial distributions, pointing to clear heterogeneity on the nucleus, perhaps formed by two chemically different planetesimals.
Investigations of Europa’s Tara Regio chaos terrain and measures of Enceladus’s plume composition allowed to directly study the chemical diversity of their internal oceans. Remote-sensing studies of these ocean worlds with JWST permitted to probe these habitats with unprecedented sensitivity and spatial resolution, revealing unique information regarding the processes acting beneath the moons’ thick ice crusts, and the potential for habitability of the sub-surface oceans.
Defending Earth: Inside NASA’s Planetary Defense Program
Kelly Fast
Acting Planetary Defense Officer
NASA Planetary Defense Coordination Office (PDCO)
PDCO Website
NASA is tasked by Congress with finding and characterizing the asteroids that pose an impact hazard to Earth, and its Planetary Defense Coordination Office carries out that work and more. This is done through a network of NASA-funded astronomers using observatories worldwide, through its centers that process asteroid observations and determine any risk to Earth, through coordination with other U.S. government agencies under a White House strategy, and through international collaborations recommended by the United Nations. NASA successfully tested asteroid deflection with the Double Asteroid Redirection Test (DART) and is currently developing the Near-Earth Object Surveyor mission that will accelerate the discovery of potentially hazardous asteroids.

Bio: Dr. Kelly Fast is the Acting Planetary Defense Officer for NASA’s Planetary Defense Coordination Office, having previously managed its Near-Earth Object Observations Program for a decade. Dr. Fast also led NASA’s Solar System Observations, Planetary Astronomy and Planetary Atmospheres research programs and she served as Program Scientist for the MAVEN mission to Mars. She investigated ozone and atmospheric chemistry on Mars, winds on Titan, and the effects on Jupiter’s stratosphere of small body impacts as an astronomer at NASA’s Goddard Space Flight Center before coming to NASA Headquarters in 2011. She earned her B.S. in Astrophysics from UCLA and her M.S. and Ph.D. in Astronomy from the University of Maryland. Main-belt asteroid 115434 (2003 TU2) was renamed “Kellyfast” in honor of Dr. Fast’s contributions to planetary science.
Supermassive black holes and their host galaxies in the early universe
John Silverman
Professor
Kavli Institute for the Physics and Mathematics of the Universe (IPMU), University of Tokyo
Visiting Professor
Johns Hopkins University
Website
Clues on the formation of supermassive black holes may be found in the properties of their host galaxies and mass relations with cosmic time. We will present results from JWST programs, while focusing on the Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) survey at z > 6. After image and spectral decomposition of NIRCam and NIRSpec data, host detections reveal their stellar masses, morphology, and properties of the stellar population. Coupled with black hole masses, we carry out one of the first assessments of the intrinsic ratio between black hole mass and stellar mass at z > 6. Lastly, the connection with lower mass black holes, including the “Little Red Dot” population, presents new insights into early phases of black hole growth and their seeding.
TBA
Punihei Lipe
Program Officer
UH Mānoa Native Hawaiian Place of Learning (NHPoL) Advancement Office
NHPoL Advancement Office Website
Coming soon.
TBA
Michael Shay
Professor
University of Delaware
Coming soon.
TBA
Diana Scognamiglio
JPL Postdoctoral Fellow
NASA Jet Propulsion Laboratory (JPL)
JPL Bio
Coming soon.
TBA
Chian-Chou (T.C.) Chen
Associate Research Fellow (Tenured)
Academia Sinica Institute of Astronomy and Astrophysics (ASIAA)
Website
Coming soon.
TBA
Mario Jurić
Professor
-and-
Senior Data Science Fellow, eScience Institute
University of Washington
Website
Coming soon.