A sophisticated new observation of a cool zone on the surface of the sun could help scientists develop a new kind of solar thermometer.
A team of astrophysicists led by researchers from the University of Glasgow are the first to use observations from the ALMA observatory in Chile to estimate the temperature of a solar prominence.
Solar prominences are zones of plasma on the surface of the sun which are contained by its powerful magnetic fields at a temperature much lower than neighbouring areas.
While areas of the sun can exceed a million degrees Kelvin, the centres of solar prominences are usually between 5,000 and 8,000 degrees. They can last for weeks before becoming unstable and erupting outwards into space.
In a paper published in the journal Monthly Notices of the Royal Astronomical Society: Letters, the researchers outline how they harnessed the ALMA observatory’s ability to generate high-resolution images of the sun using data collected from across its array of radio antennas.
This process, known as interferometry, allowed them to make a detailed examination of the temperature of a solar prominence which occurred on 19 April 2018. They examined data from the H-alpha and 3mm regions of the electromagnetic spectrum, allowing them to measure the optical thickness and brightness temperature of the prominence over the course of around two hours.
Those observations allowed them to generate images of the prominence’s spine, outlining barb-like structures on the edges of its plasma sheath. Analysis of its brightness suggested that the temperature of the plasma contained in the spine was between 6,000 and 7,000 degrees Kelvin.
Extract from Glasgow University News - read more here