Abstract
We present a visual determination of the number of bright points (BPs) existing in the quiet Sun, which are structures though to trace intense kG magnetic concentrations. The measurement is based on a 0.1 arcsec angular resolution G-band movie obtained with the Swedish Solar Telescope at the solar disk center. We find 0.97 BPs/Mm^2, which is a factor three larger than any previous estimate. It corresponds to 1.2 BPs per solar granule. Depending on the details of the segmentation, the BPs cover between 0.9% and 2.2% of the solar surface. Assuming their field strength to be 1.5 kG, the detected BPs contribute to the solar magnetic flux with an unsigned flux density between 13 G and 33 G. If network and inter-network regions are counted separately, they contain 2.2 BPs/Mm^2 and 0.85 BPs/Mm^2, respectively.
Highlights
As a part of this movement to characterize the properties of the quiet-Sun magnetism, we discovered the ubiquitous presence of bright points (BPs) in the intergranular lanes of the quiet Sun (Sanchez Almeida et al 2004)
We identify 2380 BPs, which correspond to 0.97 BPs Mm−2
According to the current paradigm, the BPs trace intense magnetic concentrations; so, our observation constrains the fraction of quiet-Sun plasma having kGs
Summary
Our understanding of the quiet-Sun magnetic fields has turned over during the last decade. In agreement with the turbulent dynamo scenario, quiet-Sun magnetic fields come with strengths in the full range from basically zero to 2 kG (Sanchez Almeida & Lites 2000; Domınguez Cerdena et al 2006). Even if they only fill a small fraction of the quiet photosphere, the part having strong kG fields may be important from a physical point of view. In an effort to calibrate with visual detection one of these methods (Bovelet & Wiehr 2001, 2007), we repeated the tedious but otherwise accurate analysis carried out by Sanchez Almeida et al (2004) This time we use a G-band image of much better quality. Our density implies that the quiet Sun has more BPs than granules, and at least 1% of the quiet solar surface is covered by BPs
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