Spectroscopic and imaging observations of small-scale reconnection events

Abstract

We present spectroscopic and imaging observations of small-scale reconnection events on the Sun. Using Interface Region Imaging Spectrograph (IRIS) observations, one reconnection event is first detected as IRIS jets with fast bidirectional velocities in the chromosphere and transition region, which are identified as non-Gaussian broadenings with two extended wings in the line profiles of SiIV, C II andMgIIk. Themagnetograms under the IRIS jets from helioseismic and magnetic images simultaneously exhibit magnetic flux cancellation, supporting the idea that the IRIS jets are driven by magnetic reconnection. Atmospheric Imaging Assembly images also show an extreme ultraviolet (EUV) brightening shortly after the underlying IRIS jets, i.e. in the 131-, 171-, 193-, 211-and 94-Å channels, implying that the overlying EUV brightening in the corona is caused by the IRIS jets in the chromosphere and transition region. We also find another three reconnection events, which show the same features during this IRIS observation. Our observational results suggest that small-scale reconnection events might contribute to coronal heating. A new result is that the process of magnetic reconnection is detected from the photosphere through the chromosphere and transition region to the corona.