ASD Colloquium Series - Spring 2026
ASD Colloquium Series - Spring 2026
The Astrophysics Science Division colloquia occur on Tuesdays at 3:45 pm in a Hybrid format. For in person attendees, the colloquia will be held in building 34, room W150 (unless otherwise noted), with an opportunity to meet the speaker at 3:30 pm. Virtual attendees should use connection information in the calendar invites.
Below is the list of scheduled talks for this period. Confirmed speakers are shown in bold face, while tentatively scheduled speakers are listed in normal face.
Schedules from past colloquium seasons are available.
Contact: Scott C. Noble
| March | |
|---|---|
| Mar 24 | Special Location: B34, W130 Standardized Space Telescopes for the Future of Scientific Discovery Aaron Tohuvavohu (Resident of the Astera institute) |
| Mar 31 | Exploring stellar activity with Sun as the template: On the missing signatures of flare-accelerated electron beams Atul Mohan (NASA-GSFC & National Astronomical Observatory of Japan) |
Abstract
Dr. Aaron Tohuvavohu is a physicist, astronomer, and explorer designing the next generation of space telescopes. He has designed missions and experiments across the electromagnetic and multi-messenger spectrum, with expertise spanning black holes, relativistic explosions, UV and X-ray instrumentation, and space systems engineering. Most recently, he led an 11-month sprint from clean sheet to launch of the highest-performance UV detector in orbit, and drove major upgrades to NASA’s Swift Observatory, significantly expanding its scientific reach, impact, and efficiency.
Abstract
Solar-stellar flares release a portion of the stored magnetic free energy in their outer atmosphere. Strong flares can accelerate particles to very high energies and produce large-scale coronal mass ejections (CMEs), both of which can destabilize planetary atmospheres and impact habitability. Unlike the Sun, stellar observations lack both spatial resolution to probe the physical scales of the active region and a means to directly probe the space-weather impacts of major flares, namely energetic particle events (EPEs) and CMEs. Decades of solar observations offer a means to explore multi-waveband sun-as-a-star parameters with high space weather diagnostic potential. Of the various multi-waveband sun-as-a-star observables, radio burst types (type-II, III, and IV) form the direct diagnostics of flare-accelerated electron beams, fundamental to the standard flare model. The occurrence of different solar burst types is very closely linked to that of EPEs and CMEs propagating into the interplanetary space. However, the detection of these bursts has been quite rare in other stars, despite several hours to days of monitoring in multiple active stars. In my talk, I will present the comprehensive sun-as-a-star catalogs of the three radio burst types using simultaneous data from multiple spacecraft in the decameter-hectometric (DH) band sensitive to EPEs and CMEs in interplanetary space heights. I will present the results on the impact of the line-of-sight effects in burst detection and the resultant impact on space weather diagnostics. I will discuss how insights from the Sun help choose the targets for stellar radio burst monitoring. I will also present our discovery of the first type-III and IV bursts in a young active M-dwarf, AD Leo.