Detection and in-depth analyses of quiet-Sun IRIS Bright Points

Llŷr Dafydd Humphries

Hosted by Aberystwyth University, United Kingdom on May 30, 2024


Observations of small-scale brightenings in the low solar atmosphere can provide valuable constraints on possible heating and heat transport mechanisms. We present a method for the detection and analysis of bright points (BPs), and demonstrate its application to time-series imagery of the Interface Region Imaging Spectrograph (IRIS) in the extreme ultraviolet. The method is based on spatio-temporal band-pass filtering, adaptive thresholding and centroid tracking, and records an event’s spatial position, duration, speed, total brightness, maximum brightness, and intrinsic brightness. Spatial area, brightness, and position are also recorded as functions of time throughout the event’s lifetime. Detected brightenings can fragment, or merge, over time – thus the number of distinct regions constituting a brightening event is recorded over time, and the maximum number of regions recorded as Nfrag, which is a simple measure of an event’s coherence or spatial complexity. The method is first tested on synthetic data based on Poisson statistics before being applied to real IRIS data. We present statistical characteristics of brightenings from the application of this method to 1330, 1400, and 2796 Å IRIS slit-jaw image time series. Several thousand events are recorded that coexist in all three channels, giving high confidence that they are real. Finally, we will also present continuing applications of this detection method to analyse a large set of BPs and their characteristics – over 12,000 BPs in total – and compare those that are found within ‘Active’ and ‘Quiet’ domains within a QS region, as well as possible future applications of the detection method.

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