New Delhi: Scientists from Aryabhatta Research Institute of Observational Sciences (ARIES) and Indian Institute of Astrophysics (IIAP), autonomous institutes under the Department of Science & Technology (DST), have probed the evolution of solar prominences over the last century.
Solar prominence is an index of solar magnetism, and its mapping can help predict solar cycles. Mapping spatio-temporal pattern of solar prominence – a large, bright, gaseous feature extending outward from the Sun’s surface for the last 10 solar cycles, the scientists have found a clear trend of poleward migration.
Dr Subhamoy Chatterjee from IIA, led by Professor Dipankar Banerjee, Director, ARIES, used the digitized data archive from Kodaikanal Solar Observatory (KoSO).
The team used KoSO digitized disc-blocked dataset, spanning over 1906-2002, to detect solar prominence locations through an automated image processing algorithm and found a clear trend of pole-ward migration. To make the detection recent, they supplemented KoSO data with those from Meudon and Kanzelhohe Observatories in Europe.
Solar prominences are anchored to the Sun’s surface in the photosphere, and extend outwards into the Sun’s hot outer atmosphere, called the corona. A prominence forms over timescales of about a day, and stable prominences may persist in the corona for several months, looping hundreds of thousands of miles into space. Scientists all across the globe are still researching how and why prominences are formed.
This study, for the first time, presents the spatio-temporal pattern of prominence for the last 10 solar cycles. They have also extracted the pole-ward migration rates of prominences for all the cycles having implication to polar magnetic flux build-up.
Current physical understanding of the self-sustained magnetic evolution of the Sun identifies polar flux at solar minima as the best precursor for predicting the following solar cycle. Also, long-term solar magnetic evolution is capable of modulating the Sun-Earth connection.
Unfortunately, no direct magnetic field measurements are available before 1967. However, historical observations reveal different features, known as magnetic proxies that map the complete picture of decadal-scale magnetic evolution. Prominence is one such vital proxy, which is aligned with the magnetic polarity inversion line and form all over the Sun depending on the phase of the solar cycle.
Such large statistics for prominence locations and inter-cycle variations will be an asset for the global heliophysics community to help in assessing magnetic evolution for decades to come.
This information was provided by the Communications Team at the Dept. of Science & Technology, Ministry of Science & Technology.
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