Periodicities in an active region correlated with Type III radio bursts observed by Parker Solar Probe

Abstract

Context. Periodicities have frequently been reported across many wavelengths in the solar corona. Correlated periods of ~5 minutes, comparable to solar p-modes, are suggestive of coupling between the photosphere and the corona. Aims. Our study investigates whether there are correlations in the periodic behavior of Type III radio bursts, indicative of non-thermal electron acceleration processes, and coronal EUV emission, assessing heating and cooling, in an active region when there are no large flares. Methods. We use coordinated observations of Type III radio bursts from the FIELDS instrument on Parker Solar Probe (PSP), of extreme ultraviolet emissions by the Solar Dynamics Observatory (SDO)/AIA and white light observations by SDO/HMI, and of solar flare x-rays by Nuclear Spectroscopic Telescope Array (NuSTAR) on April 12, 2019. Several methods for assessing periodicities are utilized and compared to validate periods obtained. Results. Periodicities of about 5 minutes in the EUV in several areas of an active region are well correlated with the repetition rate of the Type III radio bursts observed on both PSP and Wind. Detrended 211A and 171A light curves show periodic profiles in multiple locations, with 171A peaks lagging those seen in 211A. This is suggestive of impulsive events that result in heating and then cooling in the lower corona. NuSTAR x-rays provide evidence for at least one microflare during the interval of Type III bursts, but there is not a one-to-one correspondence between the x-rays and the Type-III bursts. Our study provides evidence for periodic acceleration of non-thermal electrons (required to generate Type III radio bursts) when there were no observable flares either in the x-ray data or the EUV. The acceleration process, therefore, must be associated with small impulsive events, perhaps nanoflares.

References in corpus (22)

• Key Aspects of Coronal Heating
• 25 Years of Self-Organized Criticality: Solar and Astrophysics
• Advances in Observing Various Coronal EUV Waves in the SDO Era and Their Seismological Applications (Invited Review)
• Evidence of Non-Thermal Particles in Coronal Loops Heated Impulsively by Nanoflares
• Magnetic connectivity of the ecliptic plane within 0.5 AU : PFSS modeling of the first PSP encounter
• Quasi-periodic pulsations in solar and stellar flares: an overview of recent results
• Quasi-periodic pulsations in solar and stellar flares: re-evaluating their nature in the context of power-law flare Fourier spectra
• Three-dimensional oscillatory magnetic reconnection
• Observational Signatures of Simulated Reconnection Events in the Solar Chromosphere and Transition Region
• Generation of quasi-periodic waves and flows in the solar atmosphere by oscillatory reconnection
• Statistical Study of GOES X-ray Quasi-Periodic Pulsations in Solar Flares
• Density Fluctuations in the Solar Wind Based on Type III Radio Bursts Observed by Parker Solar Probe
• Accelerated electrons observed down to <7 keV in a NuSTAR solar microflare
• Broadband Quasi-Periodic Radio and X-ray Pulsations in a Solar Flare
• Statistics and Polarization of Type III Radio Bursts Observed in the Inner Heliosphere
• IRIS observations of short-term variability in moss associated with transient hot coronal loops
• Quasi-Periodic Radio Bursts Associated with Fast-mode Waves near a Magnetic Null Point
• Detection and Interpretation Of Long-Lived X-Ray Quasi-Periodic Pulsations in the X-Class Solar Flare On 2013 May 14
• Relationship of type III radio bursts with quasi-periodic pulsations in a solar flare
• The active region source of a type III radio storm observed by Parker Solar Probe during Encounter 2
• Small electron acceleration episodes in the solar corona
• Properties of local oscillations in the lower sunspot atmosphere

Cited by in corpus (9)

• Parker Solar Probe: Four Years of Discoveries at Solar Cycle Minimum
• Upflows in the upper solar atmosphere
• Constraining Global Coronal Models with Multiple Independent Observables
• Oscillatory Reconnection of a 2D X-point in a hot coronal plasma
• The active region source of a type III radio storm observed by Parker Solar Probe during Encounter 2
• Tracking a beam of electrons from the low solar corona into interplanetary space with the Low Frequency Array, Parker Solar Probe and 1 au spacecraft
• Oscillatory reconnection as a plasma diagnostic in the solar corona
• Coronal Diagnostics of Solar Type-III Radio Bursts Using LOFAR and PSP Observations
• The independence of oscillatory reconnection periodicity from the initial pulse