Solar spicules were discovered by the Jesuit priest Angelo Secchi in 1877. They are small plasma jets of a few hundred kilometers in diameter that are launched to heights >10 Mm with speeds ranging from a few 10s of km/s to >100 km/s. Individually they have lifetimes of a few minutes. They occur in the chromospheric network over the entirety of the Sun. Early estimates (Beckers 1972) suggested that spicules […]
Polarization, regardless of wavelength, is one of the key observables for understanding the solar atmosphere because it provides information about magnetic fields, and microwave polarization is also one of them. It can reveal magnetism in the chromosphere, transition region, and corona from the microwave polarization dependencies of opacity and emissivity related to magnetic fields. Although observing solar polarization in the microwave range is not easy, it has a long history […]
The (sub)millimeter radiation of solar flares, explosive events detected as brightenings across the electromagnetic spectrum, is poorly understood (Krucker et al. 2013). The major limit of the previous >100 GHz observations was spatial resolution, impeding the combination with observations at other wavelengths. The Atacama Large Millimeter-submillimeter Array (ALMA) offers sufficient resolution for the first time. Shimizu et al. (2021) reported a microflare observed in interferometric mode. However, used as an […]
Filaments (or prominences) are “clouds” of cool (<104 K) material suspended in the solar corona by up to tens of megameters above the photosphere, and they can be broadly divided into quiescent filaments and active region (AR) filaments. Although both of these structures have been observed for a long time, particularly in recent years by NASA’s IRIS telescope, there are open questions on the magnetic topology of filaments and the […]
Observations in the ultraviolet (UV) taken with the Interface Region Imaging Spectrograph (IRIS) have shown that the bright magnetic patches, known as plage, typically feature broader and brighter MgII h and k lines, which suggests that the chromosphere above plage is hotter and denser than in the quiet-Sun (e.g., Carlsson et al. 2015). However, not all line broadening is thermal; a nonthermal broadening component of up to 10 km s$^{-1}$ […]
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