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 […]
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 […]
Microwave solar polarization observations give us information about the magnetic field of the solar atmosphere. They are important for understanding the various solar activity phenomena and emission mechanisms related to them. Polarization properties of solar active regions have been studied previously mainly at lower radio frequencies. Here we present solar radio polarization observations that were made at Aalto University Metsähovi Radio Observatory (MRO) in Finland with the 13.7-metre radio telescope, […]
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$^{-1}$ […]
There are many challenges in inferring the spatially and temporally varying temperatures of the dynamic solar chromosphere. The principal problem has been the complex formation of the spectral lines in the UV, visible, and infrared that have been the prime diagnostics to probe this region of the atmosphere. The Atacama Large Millimeter Array (ALMA), which became available for solar observations in 2016, promises to help address this issue by observing […]
Content by CESRA | WordPress theme mh-magazine-lite
