Steps toward a high precision solar rotation profile: Results from SDO/AIA coronal bright point data

Abstract

Coronal bright points (CBP) are ubiquitous small brightenings in the solar corona associated with small magnetic bipoles. We derive the solar differential rotation profile by tracing the motions of CBPs detected by the Atmospheric Imaging Assembly (AIA) instrument aboard the Solar Dynamics Observatory (SDO). We also investigate problems related to detection of coronal bright points resulting from instrument and detection algorithm limitations. To determine the positions and identification of coronal bright points we used a segmentation algorithm. A linear fit of their central meridian distance and latitude versus time was utilised to derive velocities. We obtained 906 velocity measurements in a time interval of only 2 days. The differential rotation profile can be expressed as ${\omega }_{rot}=(14.47\pm 0.10+(0.6\pm 1.0){\sin }^2(b)+(-4.7\pm 1.7){\sin }^4(b))$\degr day${}^{-1}$. Our result is in agreement with other work and it comes with reasonable errors in spite of the very short time interval used. This was made possible by the higher sensitivity and resolution of the AIA instrument compared to similar equipment as well as high cadence. The segmentation algorithm also played a crucial role by detecting so many CBPs, which reduced the errors to a reasonable level. Data and methods presented in this paper show a great potential to obtain very accurate velocity profiles, both for rotation and meridional motion and, consequently, Reynolds stresses. The amount of coronal bright point data that could be obtained from this instrument should also provide a great opportunity to study changes of velocity patterns with a temporal resolution of only a few months. Other possibilities are studies of evolution of CBPs and proper motions of magnetic elements on the Sun.

References in corpus (2)

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Cited by in corpus (6)

• Measurements of Solar Differential Rotation and Meridional Circulation from Tracking of Photospheric Magnetic Features
• A Relationship between the Solar Rotation and Activity Analysed by Tracing Sunspot Groups
• Solar differential rotation in the period 1964 - 2016 determined by the Kanzelhöhe data set
• On the variation of solar coronal rotation using SDO/AIA observations
• The rotation rate of solar active and ephemeral regions -- I. Dependence on morphology and peak magnetic flux
• Differential rotation of the solar transition region from STEREO/EUVI 30.4 nm images