Mapping solar magnetic fields from the photosphere to the base of the corona

Routine ultraviolet imaging of the Sun’s upper atmosphere shows the spectacular manifestation of solar activity; yet, we remain blind to its main driver, the magnetic field. Here, we report unprecedented spectropolarimetric observations of an active region plage and its surrounding enhanced network, showing circular polarization in ultraviolet (Mg iih & k and Mn i) and visible (Fe i) lines. We infer the longitudinal magnetic field from the photosphere to the very upper chromosphere. At the top of the plage chromosphere, the field strengths reach more than 300 G, strongly correlated with the Mg iik line core intensity and the electron pressure. This unique mapping shows how the magnetic field couples the different atmospheric layers and reveals the magnetic origin of the heating in the plage chromosphere.

A HAWAII-2RG infrared camera operated under fast readout mode for solar polarimetry

Polarimetry is a crucial method to investigate solar magnetic fields. From the viewpoint of space weather, the magnetic field in solar filaments, which occasionally erupt and develop into interplanetary flux ropes, is of particular interest. To measure the magnetic field in filaments, high-performance polarimetry in the near-infrared wavelengths employing a high-speed, large-format detector is required; however, so far, this has been difficult to be realized. Thus, the development of a new infrared camera for advanced solar polarimetry has been started, employing a HAWAII-2RG (H2RG) array by Teledyne, which has $$2048~\times 2048$$ 2048 × 2048 pixels, focusing on the wavelengths in the range of $$1.0\;{-}\;1.6\;~\mu {\text{m}} $$ 1.0 - 1.6 μ m . We solved the problem of the difficult operation of the H2RGs under “fast readout mode” synchronizing with high-speed polarization modulation by introducing a “MACIE” (Markury ASIC Control and Interface Electronics) interface card and new assembly codes provided by Markury Scientific. This enables polarization measurements with high frame-rates, such as 29–117 frames per seconds, using a H2RG. We conducted experimental observations of the Sun and confirmed the high polarimetric performance of the camera.

A HAWAII-2RG infrared camera operated under fast readout mode for solar polarimetry

Polarimetry is a crucial method to investigate solar magnetic fields. From the viewpoint of space weather, the magnetic field in solar laments, which occasionally erupt and develop into interplanetary flux ropes, is of particular interest. To measure the magnetic field in laments, high-performance polarimetry in the near-infrared wavelengths employing a high-speed, large-format detector is required; however, so far, this has been difficult to be realized. Thus, the development of a new infrared camera for advanced solar polarimetry has been started, employing a HAWAII-2RG (H2RG) array by Teledyne, which has 2048 x 2048 pixels, focusing on the wavelengths in the range of 1.0{1.6 um. We solved the problem of the difficult operation of the H2RGs under "fast readout mode" synchronizing with high-speed polarization modulation by introducing a "MACIE" (Markury ASIC Control and Interface Electronics) interface card and new assembly codes provided by Markury Scientific This enables polarization measurements with high frame-rates, such as 29{117 frames per seconds, using a H2RG. We conducted experimental observations of the Sun and confirmed the high polarimetric performance of the camera.