Sunspots

(ESO) ALMA Starts Observing the Sun

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Roman Brajsa
Hvar Observatory, University of Zagreb
Croatia

Ivica Skokic
Astronomical Institute of the Czech Academy of Sciences
Ondrejov, Czech Republic

 

This image of the entire Sun was taken in the red visible light emitted by iron atoms in the Sun’s atmosphere. Light at this wavelength originates from the visible solar surface, the photosphere. A cooler, darker sunspot is clearly visible in the disc, and as a visual comparison is shown alongside the image from ALMA at a wavelength of 1.25 millimetres. The full-disc solar image was taken with the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). Credit: ALMA (ESO/NAOJ/NRAO), NASA.

 

Astronomers have harnessed the Atacama Large Millimeter/submillimeter Array (ALMA)s capabilities to image the millimetre-wavelength light emitted by the Sun’s chromosphere — the region that lies just above the photosphere, which forms the visible surface of the Sun. The solar campaign team, an international group of astronomers with members from Europe, North America and East Asia [1], produced the images as a demonstration of ALMA’s ability to study solar activity at longer wavelengths of light than are typically available to solar observatories on Earth.

Astronomers have studied the Sun and probed its dynamic surface and energetic atmosphere in many ways through the centuries. But, to achieve a fuller understanding, astronomers need to study it across the entire electromagnetic spectrum, including the millimetre and submillimetre portion that ALMA can observe.

 

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