Hot coronal loops associated with umbral brightenings⋆
Department of Physics, University of Ioannina, 45110 Ioannina, Greece
Received: 26 April 2013
Accepted: 21 June 2013
Aims. We aim to investigate the association of umbral brightenings with coronal structures.
Methods. We analyzed AIA/SDO high-cadence images in all bands, HMI/SDO data, soft X-ray images from SXI/GOES-15, and Hα images from the GONG network.
Results. We detected umbral brightenings that were visible in all AIA bands as well as in Hα. Moreover, we identified hot coronal loops that connected the brightenings with nearby regions of opposite magnetic polarity. These loops were initially visible in the 94 Å band, subsequently in the 335 Å band, and in one case in the 211 Å band. A differential emission measure analysis revealed plasma with an average temperature of about 6.5 × 106 K. This behavior suggests cooling of impulsively heated loops.
Key words: sunspots / Sun: corona / Sun: magnetic topology
Two movies are available in electronic from at http://www.aanda.org
© ESO, 2013