Astronomers studied the loss of plasma sediments from the Sun’s atmosphere to its surface. It turned out that the “rains” from the droplets of plasma go even where scientists did not at all suppose. The study of this process should help to solve the riddle of the warming up of the corona of the luminary.
On the Sun there are also precipitation, only in the form of plasma, and not water, as on Earth, and physically it is literally equivalent phenomena. This occurs when a hot plasma enters a colder region, condenses into droplets, and falls to the surface. Astronomers are interested in these processes mainly in order to understand the mechanism of heating the star corona. It is known that the temperature of the upper rarefied layers of the Sun, which are visible during a total eclipse, is approximately 100 times greater than the temperature of the visible surface – the photosphere. Astronomers offered a lot of potential explanations, but so far none has received the status of the generally accepted.
In her report, Emilia Mason from the Catholic University of America in the USA told about new observations of “coronal rains”. Scientists have already observed them, but usually not far from flares. However, new results say that they can go wherever there is a sufficient decrease in corona temperature with altitude.
Theoretical models predicted that such a rain should occur in streamers-large loop-like structures from a plasma up to six star radii held by a large-scale magnetic field between groups of sunspots of different polarities.
They failed to detect rain, but it was found in much smaller loops related to zero points of the topology of the magnetic field, whose size is only 0.1 of the radius of the Sun. In one case, precipitations in the form of a plasma were observed in this region for 30 hours.
From the theoretical point of view, this is strange, since in much smaller loops the temperature difference should be much smaller, which makes sedimentation difficult. The idea of the authors is that in streamers the temperature varies much more smoothly, because of which the plasma is not going to large drops, but falls in the form of a fog that can not be fixed with today’s instruments.
This hypothesis is confirmed by the fact that scientists observed less noticeable rain in pseudo-stems, which connect the spots of one polarity, and in size occupy an intermediate position. Astronomers are hoping to see even small droplets of plasma with new tools, such as the currently under construction in Hawaii Solar Telescope named Daniel Inoue.