ALMA have started to observe the Sun

This ALMA image of an enormous sunspot was taken at a wavelength of 1.25 millimetres. Credit: ALMA (ESO/NAOJ/NRAO)

ALMA have started to observe the closest star, our sun, astronomers are using ALMA's capabilities to image the millimetre-wavelength light emitted by the Sun’s chromosphere, that is the region that lies just above the photosphere, which forms the visible surface of the Sun, revealing stunning details of our Sun, including an evolving sunspot which nearly twice the diameter of the Earth. 

This was done by an international group of astronomers with members from Europe, North America and East Asia, producing 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.

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. Credit: ALMA (ESO/NAOJ/NRAO), NASA.

ALMA typically observes faint objects but the Sun is many billions of times brighter so the antennas were designed so they could image the Sun without being damaged by the intense heat of the focused light. The obtained results show the capacity that the observatory can achieve and it is an important expansion of the range of observations that can done with ALAMA.

A map of the whole disc of the Sun was also made with a single ALMA antenna, using a technique called fast-scanning, at a wavelength of 1.25 millimetres. The accuracy and speed of observing with a single ALMA antenna make it possible to produce a map of the entire solar disc in just a few minutes. These maps show the distribution of temperatures in the chromosphere over the whole disc at low spatial resolution and therefore complement the detailed interferometric images of individual regions of interest. Credit: ALMA (ESO/NAOJ/NRAO)

Sources: ALMA, ESOS, Wikipedia