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Differences in physical properties of coronal hole and quiet Sun coronal bright points and their ALMA counterparts

Coronal bright points (CBPs) are a fundamental class of solar activity phenomenon. They represent a set of small-scale loops in the low corona that have an enhanced ultraviolet (UV)/extreme- ultraviolet (EUV) and X-ray emissions. CBPs are found in- and outside of coronal holes (CHs), and with that can be used as proxy to investigate low coronal characteristics of CHs, especially their magnetic field topology. As CHs are the primary sources of high-speed solar wind streams, CBPs might serve as important input for solar wind models. Using EUV 193 Å and magnetogram data obtained by Solar Dynamics Observatory (SDO) and full-disk Band 6 (λ = 1.21 mm) radio data by Atacama Large Millimeter/submillimeter Array (ALMA), we report measurements of the intensity and area of coronal bright points within five CHs observed at different times near the centre of the solar disk and in the quiet Sun (QS) regions. CBPs were identified based on EUV and magnetogram data and measurements of the mean intensity and area of the detected CBPs were conducted for both SDO EUV and ALMA Band 6 images. Then, an unequal variances t- test was conducted on randomly chosen CBP samples using a bootstrap technique to determine if CH and QS CBPs show any differences in the measured physical properties. Statistical analysis of the measured physical properties revealed that CBPs within CHs have on average a significantly lower mean intensity as well as a lower area than the QS CBPs. This was the case for both SDO and ALMA data. Future study will follow the evolution of the physical properties (intensity, morphology and magnetic field) of both CBPs and CHs in order to determine the true causes of the observed CBP differences with a focus on the magnetic field and morphology of the CHs as one of those possible causes.

corona ; coronal bright point ; UV radiation ; plasma ; radio radiation

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