Events Daily

Friday, March 24, 2023

Exoplanet Atmospheres and the Search for Signs of Life Beyond Earth
Sara Seager, Massachusetts Institute of Technology
Event Type: Special Seminar
Time: 11:00 AM - 12:30 PM
Location: Speaker: Zoom; Audience: 940 or Zoom
Abstract: Thousands of exoplanets are known to orbit nearby stars and small rocky planets are established to be common. The ambitious and lofty goal of identifying a habitable or inhabited exoplanet is within reach—by the new James Webb Space Telescope’s (JWST) capability for observations of exoplanet atmospheres for water vapor and gases that might be attributed to life. The JWST uses transmission spectroscopy, a technique that relies on disentangling the host star and planet signals, and for atmospheres of rocky planets orbiting in the habitable zone of their host stars is limited to small red dwarf host stars. Yet now that we are faced with the unprecedented quality of JWST data, the community faces two major challenges. The first is that low-level host star variability caused by stellar surface inhomogeneity from magnetic fields can dominate the exoplanet atmosphere signal. The second challenge comes from significant inconsistencies when applying intricate inverse-problem algorithms to retrieve atmospheric parameters from data. Can we overcome these challenges or will the identification of a habitable or inhabited exoplanet have to wait for the next generation of “direct imaging” space-based telescopes.

Link to the Event Video

What's in a phase, or how the topology of the QCD vacuum influences the spin of the proton
Raju Venugopalan, Brookahaven
Event Type: Informal HEP Talk
Time: 2:00 PM - 3:00 PM
Location: 726 Broadway, 940, CCPP Seminar
Abstract: We now understand the proton to be a complex many-body system of quarks and gluons described by quantum chromodynamics. How does this symphony of ``partons" determine the proton's spin? We focus here on the proton's helicity and argue that it is determined by the topological susceptibility of the QCD vacuum. A key role is played by a Wess-Zumino-Witten term for a primordial eta-prime Goldstone with the dynamics of the proton's helicity described by the corresponding axion-like effective action. We show that the proton's helicity measured by a very high energy probe is quenched by a drag force determined by the rate of topological (sphaleron) transitions. We argue that first evidence for such sphaleron transitions in nature can be obtained from polarized deeply inelastic scattering experiments at the Electron-Ion Collider under construction at Brookhaven National Laboratory.

Link to the Event Video

Event Type: HEP Discussion Sessions
Time: 3:30 PM - 5:30 PM
Location: 726 Broadway, 901, Sm Conf