Quiet Sun magnetic fields are thought to significantly contribute to the energy and heating of the solar atmosphere. The question is: how much? A post written by Rebecca Robinson, from the Rosseland Centre for Solar Physics/Institute of Theoretical Astrophysics (Norway).
The quiet Sun at disk center measured by Hinode on 10 March 2007, 11:37 UT. Credit: ISAS/JAXA, NAOJ, NASA, STFC, ESA.
The quiet Sun (usually shortened as QS) is represented by the regions of the Sun's photosphere that have relatively weak magnetic field when compared to the strong fields found in active regions and sunspots. Even though the quiet Sun is not as locally energetic as active regions, the majority of the Sun's photosphere is quiet most of the time. This makes the quiet Sun an important area to study.
The image illustrating this article shows the continuum intensity and saturated Stokes V polarisation of the quiet Sun as measured by Hinode at the center of the solar disk on 10 March 2007, 11:37 UT.
Because of their consistent and relatively ubiquitous presence across the photosphere, quiet Sun magnetic fields are thought to significantly contribute to the energy and heating of the solar atmosphere. The question is: how much? While active regions contribute to atmospheric heating over short timescales, QS magnetic fields are expected to contribute over long-term scales. In fact, the total flux content of the QS has been measured to be slightly larger than the flux content of all active regions during solar maximum, suggesting that the QS is likely a significant contributor to the atmospheric energy budget!
To understand the importance of the quiet Sun to the upper layers of the solar atmosphere, we need extremely high resolution observations of the magnetic field in such regions. By means of observations using the spectropolarimetric instrumentation on the European Solar Telescope, we will better understand the strength, distribution, and energy of the magnetic field in the QS. This will allow us to get a better grasp on the link between the ubiquitous quiet Sun and the energetic solar atmosphere.