Wed. Sep 28th, 2022

Scientists finally know what heats the solar corona

Usually, the farther away from the heat source, e.g. candle or stove flame, the cooler the. It’s different on the sun. The solar corona is much hotter than layers closer to the solar core of the. Scientists have long wondered why this happens. Now they have succeeded in showing that the solar corona can heat the so-called. Alfvén waves.

The solar atmosphere is divided into three layers: the photosphere closest to the Sun, the central chromosphere and the outermost solar corona. The temperature of the plasma in the solar corona is as high as 2-3 million Kelvinów (K). Meanwhile, lying 2,000. km below the photosphere is "cold" – Its temperature is only 5.8 thousand. K.

– The hot solar corona goes against our intuition, która tells us that the temperature should decrease with distance from the source of theóheat sources. After all, the farther away from the candle or stove, the temperature decreases. It is different on the Sun – the mówi PAP astrophysicist Prof. Krzysztof Murawski of the Maria Curie-Sklodowska University in Lublin.

Although the temperature decreases with distance from its hot core (15 million K) up to an altitude of 100 km above the photosphere, reaching there only 4.3 thousand. K, but above that, the temperature begins to rise unexpectedly; initially the rise is slow in the chromosphere, but already at its peak, in the so-called “chromosphere”. transition area, the temperature rises sharply up to temperatures in the millions.

The mechanism of this process remained unknown until now. The problem with explaining the temperature anomaly in the Sun’s atmosphere was that the plasma is immersed in a complex magnetic field. Over a period of several decades, many centersóIn scientific próhas been unraveling this problem, providing often sophisticated scenarios describing the process of heating the solar corona.

The issue was also addressed by an international team ofóA panel consisting of scientistsów of five countryów, led by Prof. Abishka Srivastava of India. Using observational data from the so-called. Swedish Telescope located in La Palma in the Canary Islands, scientists observed on the Sun’s so called “faint”. Alfv waveséAt.

– The waves have been known since 1942. Swedish scientist Hannes Alfvén received a Nobel Prize for their research. Until now, we thought they were róalso on the Sun, but we could not notice them. They were first observed by a team ofół from Ireland PóThe team first observed jets ejected from black holes in the North, observing structures with a size of 100-200 km. These structures resemble the włókna whether wicker vittles sticking up perpendicular to the surface of the sun. They perform oscillations, or fluctuations, whichóThe effect of which are the waves of Alfvéon – describes Prof. Murawski, który was part of the research team.

Its compositeół as part of the project performed advanced numerical simulations and showed that Alfv waveséon can heat the solar corona and generate the solar wind. – Using numerical simulations, we have shown that these waves are able to provide energy to the solar corona. Krótko mówn, these waves have high enough energy to heat the solar corona. If it did not get energy from within, it would quickly cool down, explains Prof. Murawski.

– Our discovery provides a revolutionary solution to the long-known puzzle of solar coronal heating and introduces a breakthrough in the understanding of the processóIn the generation of energy and its transport from cold to hot areasóin the Sun’s atmosphere. Alfv waveséon participate róAlso in many other phenomena. Amongód of them include jets ejected from black holes,” explains Prof. J. K. K., who is a member of the team. Murawski.

Now scientists at the UMCS will conduct further research. They want to see how it happens that Alfven wave energy is converted into thermal energy that warms the solar corona.

Alfv detection reportéon the Sun were published in a prestigious journal "Nature". The international team of oprócz Poleów: prof. Christopher Murawski and Mgr. Dariusz Wójcik from UMCS, entered researchers from Northern Ireland., UK, India and Italy.

Sourceósource: PAP – Science in Poland, Ewelina Krajczyńska. Photo. NASA/SDO/AIA/Goddard Space Flight Center