Monday

We present 10 microflares from a recently emerged active region, AR12721, that were observed on 2018 September 9-10. Using both the Nuclear Spectroscopic Telescope Array (NuSTAR) and the Solar Dynamics Observatory’s Atmospheric Imaging Assembly (SDO/AIA) the temporal, spatial, and spectral evolution of the microflares can be studied to determine the energy released, and the associated heating of the solar atmosphere. NuSTAR is an astrophysical X-ray telescope, with direct imaging spectroscopy providing a unique sensitivity for observing the Sun above 2.5 keV. The active region microflares were below GOES A1 equivalent level with energies of 10^26–10^28 erg. From the NuSTAR X-ray spectra, we find that temperatures up to 10 MK are reached with one microflare identified to be the faintest non-thermal X-ray microflare on record. We also present evidence of photospheric magnetic flux cancellation/emergence at the footpoints in 8 of the 10 microflares using the Solar Dynamics Observatory’s Heliospheric and Magnetic Imager (SDO/HMI).