Joint Physics Dept.–Inst. for Space Weather Sci. Colloquium

October 26, Monday

Millisecond radio bursts from flare stars:

A new type of probes of stellar magnetic fields and plasma dynamics

Jiale Zhang

Peking University

(Solar Physics, Host: Bin Chen)

Room: ECE 202

Time: 11:45 am - 12:45 pm with 11:30 am teatime

Zoom ID for those who cannot attend in-person: 955 9399 6954

(APPROVAL by Prof Ahn REQUIRED for APPH/MTSE PhD students to attend online)

*Password: check email or request from kenahn@njit.edu

Radio observations of nearby flare stars offer a valuable avenue to measuring their magnetic fields and monitoring magnetic activity and space weather events that have potential impacts on the habitability of surrounding exoplanets. Using the high-resolution radio observations taken by the world’s largest single-dish radio telescope, the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we recently discovered a peculiar type of millisecond bursts from a prototypical flare star AD Leo. In this talk, I will present the phenomenology of these bursts and discuss their astrophysical implications (1) radio fine structures as evidence of electron cyclotron maser instabilities; (2) ultrafast frequency-drifting bursts as probes of unresolved, small-scale magnetic field structures near the surface; (3) modulation lanes as tracers of refraction-related propagation effects in stellar coronae. I will conclude by highlighting ongoing efforts to extend these techniques to other radio-active stellar systems and the importance for coordinated multi-wavelength observations in the future.