Short-duration active region brightenings observed in the extreme ultraviolet and Hα by the Solar and Heliospheric Observatory Coronal Diagnostic Spectrometer and Hida Domeless Solar Telescope

We present the first detection of an Halpha counterpart to the EUV blinker. The observations come from a coordinated campaign between the Hida Observatory Domeless Solar Telescope (DST) and the Solar and Heliospheric Observatory Coronal Diagnostic Spectrometer (CDS) conducted in 2002 July and August. Utilizing studies designed for high-cadence observations, many short-duration brightenings (< 3 minutes) were identified in the He I λ584.334 and O v λ629.732 spectral lines in CDS data of active region NOAA 10039/10044. These brightenings show similar characteristics ( increases in intensity, size) to longer duration EUV blinkers previously reported in active regions and the quiet Sun. Focusing on two events that show pronounced emission in the upper chromosphere (He I), we have been able to identify cospatial bright points in the lower chromosphere (Hα center, +/-0.5 &ANGS;) that show enhanced emission during the EUV blinker. These bright features have lifetimes similar to those of their EUV counterparts, and their peak intensities occur nearly simultaneously with the peak blinker intensities in the He I and O v lines. In both cases the He I and O v lines show excess line broadening at the peak of the event (> 15 km s(-1)). Our high-cadence observations also enabled us to examine the dimensions and lifetimes of short-duration active region blinkers in detail. We find that the instrumental spatial and temporal resolution can combine to distort their characteristics: even short-duration blinkers appear to be composed of elementary brightening events. The optical brightenings also appear to closely follow the behavior of the elementary brightenings. The spatial and temporal relationships between the brightenings indicate a causal link between the EUV and Halpha blinkers.