Evidence for a Transition Region response to penumbral microjets in sunspots
Abstract
Penumbral microjets are short-lived, fine-structured and bright jets that are generally observed in chromospheric imaging of the penumbra of sunspots. Here we investigate their potential transition region signature, by combining observations with the Swedish 1-m Solar Telescope (SST) in the Ca II H and Ca II 8542{\AA} lines with ultraviolet imaging and spectroscopy obtained with the Interface Region Imaging Spectrograph (IRIS), which includes the C II 1334/1335{\AA}, Si IV 1394/1403{\AA} and Mg II h & k 2803/2796{\AA} lines. We find a clear corresponding signal in the IRIS Mg II k, C II and Si IV slit-jaw images, typically offset spatially from the Ca II signature in the direction along the jets: from base to top, the penumbral microjets are predominantly visible in Ca II, Mg II k and C II/Si IV, suggesting progressive heating to transition region temperatures along the jet extent. Hence, these results support the suggestion from earlier studies that penumbral microjets may heat to transition region temperatures.
Cite
@article{arxiv.1509.01402,
title = {Evidence for a Transition Region response to penumbral microjets in sunspots},
author = {Gregal J. M. Vissers and Luc H. M. Rouppe van der Voort and Mats Carlsson},
journal= {arXiv preprint arXiv:1509.01402},
year = {2015}
}
Comments
Accepted for publication in the Astrophysical Journal Letters. 6 pages, 5 figures