Relation of transition region blinkers to the low chromosphere

Kiepenheuer-Institut für Sonnenphysik, Schöneckstr. 6, 79104 Freiburg, Germany

Corresponding author: A. Brković, alen@kis.uni-freiburg.de

Received: 12 March 2003
Accepted: 12 May 2003

Abstract

We investigated the coupling between the low chromosphere, lower and upper transition region through the study of blinkers. Blinkers are extreme ultraviolet (EUV) small-scale transient brightenings best detected in transition region lines showing an intensity enhancement on the % level on average. We analysed time-series spectra of the C II,1037 Å ( K, lower transition region) and O VI, 1038 Å ( K, upper transition region) lines, as well as the C I, continuum at 1042 Å formed about 1 Mm above the solar surface, obtained with the Solar Ultraviolet Measurement of Emitted Radiation (SUMER) spectrometer on SOHO. Blinkers detected in C II, and O VI, have similar enhancement levels. We found a modest space-time overlap between blinkers in the two lines and a small correlation between C II, or O VI, blinkers and the corresponding light curve in the chromospheric continuum. This suggests a relation of EUV blinkers to the chromosphere, which could support the idea that blinkers are the consequence of granular collisions. The average duration of O VI, blinkers amounts to 10.0 min and of C II, blinkers to 6.7 min.