About this Research Topic
Magnetism defines the complex and dynamic solar corona. The energy necessary to drive eruptive phenomena in the corona originates primarily from the magnetic field. Eruptions in the form of coronal mass ejections (CMEs) are transient in the ever-outflowing solar wind, which itself possesses a three-dimensional morphology shaped by the global coronal magnetic field. Coronal magnetism is thus at the heart of any understanding and predictive capability of how the Sun affects the Earth.
Such an understanding will ultimately require the specification of the time-evolving global solar coronal magnetic field. Given this knowledge, it becomes possible to determine where magnetic free energy is stored, what triggers the eruptive events that release this energy, where solar energetic particles are accelerated and how they propagate, and how CME internal magnetic structure evolves in response to interactions with the surrounding corona and solar wind.
Until recently, our knowledge of magnetism in the corona was primarily limited to what we could infer from solar surface observations. However, current and planned polarimetric observations of the corona itself have made the development of coronal magnetometric techiques a priority. Coronal magnetometry is a subject that would benefit from a concerted effort to draw together the different strands of research happening around the world. The purpose of this Frontiers Research Topic on Coronal Magnetometry is to provide a forum for comparing and coordinating these research methods.
In particular, we welcome papers with relevance to one or more of the following general areas.
1) Observations: A key development of recent years has been the availability of coronal polarimetric measurements at visible and infrared wavelengths (CoMP, OFIS, CorMag). Telescopes under construction will take these observations to the next level of resolution/sensitivity (DKIST), and to radio wavelengths (EOVSA, CSRH). Future proposed ground-based telescopes have the potential to comprehensively observe the global coronal field at wavelengths from radio through infrared to visible (COSMO, FASR, MWA), and, with the extension to satellite observations, into the ultraviolet and extreme ultraviolet (MASC). Papers are welcomed that analyze current data or define capabilities of future observations.
2) Diagnostics: A broad range of physical processes can yield information about the coronal magnetic field, including but not limited to the Zeeman and Hanle effects, gyroresonance, gyrosynchrotron and bremstrahllung radiation, Faraday rotation, and coronal seismology. Papers are welcomed that examine the physical underpinnings and assumptions of these processes, and their application as diagnostics to different regions of the corona (active region, quiet sun, on-disk, limb, etc.)
3) Models and methodologies: The ultimate goal is to build a 3D global coronal magnetic field. To do so will necessarily draw upon the observations and diagnostics described above, but also is likely to require the explicit utilization of boundary-driven numerical models. Methodologies for drawing together models and observations in an efficient fashion need to be developed, including forward and inverse techniques. Papers are solicited that describe and apply numerical models and extrapolations, and techniques for constraining models with multiwavelength observations.
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.