Paper detail

Tracing the magnetic field topology of the quiet corona using propagating disturbances

The motion of faint propagating disturbances (PD) in the solar corona reveals an intricate structure which must be defined by the magnetic field. Applied to quiet Sun observations by the Atmospheric Imaging Assembly (AIA)/Solar Dynamics Observatory (SDO), a novel method reveals a cellular network, with cells of typical diameters 50\arcsec\ in the cool 304Å channel, and 100\arcsec\ in the coronal 193Å channel. The 193Å cells can overlie several 304Å cells, although both channels share common source and sink regions. The sources are points, or narrow corridors, of divergence that occupy the centres of cells. They are significantly aligned with photospheric network features and enhanced magnetic elements. This shows that the bright network is important to the production of PDs, and confirms that the network is host to the source footpoint of quiet coronal loops. The other footpoint, or the sinks of the PDs, form the boundaries of the coronal cells. These are not significantly aligned with the photospheric network - they are generally situated above the dark internetwork photosphere. They form compact points or corridors, often without an obvious signature in the underlying photosphere. We argue that these sink points can either be concentrations of closed field footpoints associated with minor magnetic elements in the internetwork, or concentrations of upward-aligned open field. The link between the coronal velocity and magnetic fields is strengthened by a comparison with a magnetic extrapolation, which shows several general and specific similarities, thus the velocity maps offer a valuable additional constraint on models.