DAO Astronomy Colloquium


DAO Colloquium Schedule

We have a mixture of fully remote and in person talks. In person talks will take place in the LCR and will also be streamed live online via Zoom.

Tuesdays at 11am unless otherwise indicated with (***)

Archive of previous seminar schedules (2010-)

 

Fall 2024

Tues. September 10: Jenny Greene (Princeton), virtual Recording

The Nature of “Little Red Dots” 
One of the most surprising results from JWST has been the discovery of a large population of compact red sources at z>4, with very red rest-frame optical colors, blue UV slopes, and broad Balmer lines. The compact sizes and luminous broad lines strongly suggest these objects are powered by accreting supermassive black holes, but their lack of evidence for X-ray emission or hot dust in the mid-infrared calls that conclusion into question. Regardless, their high number densities (~5% of the galaxy population) makes them an important new contribution to the high-redshift galaxy zoo. I will discuss our ongoing efforts to understand the nature of this population, and what they may teach us about the growth of black holes and galaxies.

Tues. September 17: Rebecca Jensen-Clem (UCSC), virtual Recording

Exoplanet Imaging with Extremely Large Telescopes
The last three decades have been marked by the discovery of over 5000 exoplanets orbiting nearby stars. Unraveling these planets’ compositions, climates, and formation histories requires spectra of their thermal emission and reflected starlight; direct imaging is the only path forward for obtaining high signal-to-noise, high-resolution spectra of diverse exoplanet atmospheres. Today, only a handful of massive super-Jupiters have been imaged, while faint Earth-sized planets remain hidden in the glare of their host stars. My work combines adaptive optics (AO) technology development with high contrast observations to advance the state-of-the-art in exoplanet imaging. In this talk, I will discuss (1) the limits of today’s high contrast imaging systems and the AO technology development efforts at UC Santa Cruz and W. M. Keck Observatory that aim to address these limitations, including primary mirror segment phasing, multi-stage wavefront sensing, and astrophotonics; (2) the new high contrast science enabled by these technology development activities with today’s 10-meter-class telescopes and the next generation of 30-meter-class telescopes.

Tues. September 24: Danny Horta (Flatiron), in person Recording
 
A glimpse into the Milky Way’s distant past: unravelling the Galaxy’s early assembly history with large stellar surveys
Unravelling galaxy formation theory requires understanding galaxies both at high and low redshifts. A possible way to connect both realms is by studying the oldest stars in the Milky Way (i.e., the proto-Galaxy). Our ability to resolve individually millions of stars in the Galaxy provides us with the opportunity to decipher the intricate processes of galaxy formation in a detail that is unmatched by any other galaxy in the Cosmos. Therefore, the time is ripe to study the oldest parts of the Milky Way, and from them unravel its early mass assembly history. Such results, in addition to placing strong constraints on how our Galaxy formed, are also complementary to the new exciting results of the high-redshift Universe delivered by the JWST telescope. In this talk, I will present new findings aiming to piece together the earliest stages of formation of the Milky Way by examining the chemistry, kinematics, and orbits of the oldest stars in the Galaxy. I will also show fresh results concerning the structure and mass of the Milky Way’s proto-galactic fragments. I will then place these observational findings in the wider context of the many possible assembly histories by comparing with expectations from cosmological simulations. The findings I will present help answer (but raise more) fundamental questions on the genesis of our Galaxy.

Tues. October 22nd: Matthew Lehner (ASIAA), in person Recording

The Transneptunian Automated Occultation Survey (TAOS II)

The TAOS II survey is designed to measure the size distribution of small Trans-Neptunian Objects (TNOs), critical for understanding the formation and evolution of our Solar System. These objects are too faint for direct detection, so TAOS II will search for rare and brief occultations of stars by TNOs, requiring high-cadence observations across three telescopes at San Pedro Martir Observatory in Mexico. With cutting-edge CMOS imagers, TAOS II will collect an unprecedented dataset, offering rich opportunities for both core occultation science and additional research.

TAOS II is a collaboration between ASIAA (Taiwan), NRC (Canada), IA-UNAM (Mexico), and the CfA (USA). Members of the four collaborating institutes will have first access to this dataset. As such, members from these institutes are strongly urged to contribute to the scientific output of this survey, preferably in collaboration with members of other collaborating institutes.

In this presentation, I will outline the survey’s key science objectives, the unique capabilities of the TAOS II facility, and collaborative opportunities within the international team. I will also preview the upcoming TAOS II science workshop next spring.

 

Tues. October 29th: Mike Brown (Caltech), remote Recording

Planet Nine from Outer Space
Astronomers have been predicting and searching for planets beyond Neptune for almost 180 years. In all previous cases the predictions were based on bad data, bad physics, or both, and the predictions turned out to be wrong. In 2016, we joined this inglorious group and declared that orbital alignments of the most distant objects in the solar system demand the presence of a distant giant planet on an eccentric and inclined orbit. I’ll describe the mounting evidence for this planet, discuss the counter-proposals, and talk about the ongoing search for what would be the fifth largest planet of our solar system.