After hydrogen, helium is considered to be the second most abundant element in the universe. How much of it is in the atmosphere of the Sun, the scientists do not know, it is difficult to measure. But knowledge about this will help to understand the origin and acceleration of the solar wind that is a constant stream of charged particles from the Sun. The study of the star's atmosphere began in 2009.
Then NASA launched a research probe that's task was to measure the content of the helium in the solar atmosphere. Previous measurements boiled down to the fact that the ratio of helium to the hydrogen was determined when they reached the Earth.
And the scientists were disappointed that these ratios were lower than expected. It was assumed that the lack of the helium can remain in the outer layers of the Sun's atmosphere, or rather in the corona. The probe made a number of observations that helped the astronomers to understand - indeed, the helium is present in the corona, and it is unevenly distributed.
In the equator of the Sun, it was almost absent, and in the territories of middle latitudes - more than enough. By comparing the probe images with those obtained from the observatory of the European Space Agency, the scientists were able to identify the distribution of the helium fluxes with changes in the solar wind around the Earth.
That fact makes it clear that the solar atmosphere is more dynamic than scientists thought. The probe rocket transmits new images that explain the slow component of the solar wind. The probe's equipment is capable of investigating the elemental composition of a certain area, in which solar wind flows are accelerating.
That process is being studied concurrently with measurements of the inner solar system. The scientists believed that the excess solar heat directed ionized hydrogen protons away from the Sun in the form of a supersonic wind.
But a special approach to physical processes should help to understand how heavier elements such as helium are accelerated. Thus, detailed knowledge of the abundance of elements in the atmosphere of the Sun provides additional information about the processes of acceleration of the solar wind.