NuSTAR observations of a repeatedly microflaring active region

Jul 8, 2021, 6:35 PM


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Working Group 1: Flare thermal response Working Group 1: Flare thermal response


Kristopher Cooper (University of Glasgow)


The Nuclear Spectroscopic Telescope Array (NuSTAR) is an astrophysical X-ray telescope capable of observing the Sun with direct imaging spectroscopy providing a unique sensitivity >2.5 keV. We use NuSTAR to investigate highly frequent and weak flares (microflares) thought to contribute to heating the Sun's atmosphere particularly in active regions. I will present several X-ray microflares from a recently emerged active region, AR12721, that were observed on 2018 September 9-10 with NuSTAR. In combination with SDO/AIA, I describe the temporal, spatial, and spectral evolution of these GOES sub-A class microflares that reach temperatures above those of the surrounding active region (>5 MK). One of the microflares presented is the faintest non-thermal microflare so far observed with NuSTAR with an equivalent GOES class of A0.1. Using SDO/HMI, I also present evidence of photospheric magnetic flux cancellation/emergence at the footpoints in 8 of the NuSTAR microflares.


Primary author

Kristopher Cooper (University of Glasgow)


Dr Iain G. Hannah (University of Glasgow) Dr Brian W. Grefenstette (California Institute of Technology) Dr Lindsay Glesener (University of Minnesota Twin Cities) Dr Säm Krucker (University of Applied Sciences and Arts Northwestern Switzerland & Space Sciences Laboratory University of California, Berkeley ) Dr Hugh S. Hudson (University of Glasgow & Space Sciences Laboratory University of California, Berkeley) Dr Stephen M. White (Air Force Research Laboratory, Space Vehicles Directorate) Dr David M. Smith (Santa Cruz Institute of Particle Physics and Department of Physics) Ms Jessie Duncan (University of Minnesota Twin Cities)

Presentation materials