Speaker
Description
First Name: Vratislav
Last Name: Krupar
Affiliation: GPHI/UMBC & NASA/GSFC
All authors: Vratislav Krupar
Abstract: We report a long-lasting hectometric (0.5–3 MHz) Type IV radio continuum that persists for nearly 19 days and corotates with the Sun. The emission is seen in sequence by Solar Orbiter, Wind, and STEREO-A, indicating a stable source that rotates through favorable viewing angles. During the STEREO-A interval it is strongly left-hand circularly polarized (degree of circular polarization above 0.9) and shows 45–60 minute quasi-periodic pulsations, which we interpret as standing fast/Alfvénic MHD modes in a large coronal trap. Using a new single-spacecraft localization method, the wavevector-corrected ray-sphere (WCRS), we place the source near a helmet streamer and estimate a transverse size of about 2.5–3.0 solar radii. The apparent angular width is much larger than this, implying strong interplanetary scattering. Three fast CMEs likely replenished trapped electrons and sustained the continuum, demonstrating a new duration record for Type IV emission and showing how WCRS can enable single-point tracking of heliospheric radio sources for space-weather forecasting.