Scientists have spotted a new view of the dark, contorted centre of a sunspot that is nearly twice the diameter of the Earth. It was spotted using Atacama Large Millimetre/submillimetre Array (ALMA) antennas located in Atacama Desert of northern Chile. The discovery is an important expansion of range of observations that can be used to probe the physics of our nearest star.
- Using ALMA antennas capabilities, astronomers imaged the millimetre-wavelength light emitted by the Sun’s chromosphere, the region that lies just above the photosphere that forms the visible surface of the Sun.
- They produced the images to study solar activity at longer wavelengths of light that are typically available to solar observatories on Earth.
- Using two of ALMA’s receiver bands at wavelengths of 1.25 millimetres and three millimetres, scientists were able to observe an enormous sunspot.
- The images captured through it help to reveal differences in temperature between parts of the Sun’s chromosphere and also understanding the heating and dynamics of the chromosphere.
- The Atacama Large Millimetre/submillimetre Array (ALMA) antennas designed so that they could image the Sun in exquisite detail using the technique of radio inter-ferometry.
- It is used to image the millimetre-wavelength light emitted by the Sun’s chromosphere.
- The images demonstrate ALMA’s ability to study solar activity at longer wavelengths of light than are typically available to solar observatories.
They are darker, cooler areas on the surface of the sun in a region called the photosphere (having temperature 5,800 degrees Kelvin). Sunspots can be very large, up to 50,000 kilometers in diameter and have temperatures of about 3,800 degrees K. They are dark in comparison with the brighter and hotter regions of the photosphere surrounding them.