TASS, April 30th. Astronomers followed fluctuations in the brightness of nearly 400 sun-like stars and found that their level of flare activity was significantly higher than that of the Sun. The results of their observations published a scientific journal Science.
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“We were very surprised that most of the stars, similar to the Sun in properties and sizes, are much more active than our stars. At the same time, we admit that there are no such differences. In that case, in the last 9 thousand years our luminary was unusually “quiet”, which the theory allows, “commented one of the authors of the study, an astrophysicist from the Institute for the Study of the Solar System in Gottingen (Germany), Alexander Shapiro.
Astronomers have long known that flashes periodically occur on the Sun, during which the luminosity abruptly releases a huge amount of energy in the form of waves of optical, thermal and x-ray radiation. Powerful events of this kind can disrupt the operation of satellites in orbit and interfere with radio communication systems on Earth, as well as threaten the health of astronauts.
The largest solar flare in human history occurred in 1859 during the so-called Carrington events. It generated approximately 10 yottajoules (10 to the 25th power) of energy and was ten times greater than the meteorite that destroyed dinosaurs and marine reptiles at the end of the Mesozoic.
Astronomers have long been interested in how often such powerful flashes occur on stars similar to the Sun, as well as on luminaries of another type, around which planets revolve, which in size and properties are similar to Earth. The answers to both of these questions are very important both in order to predict the future of mankind, and in order to search for extraterrestrial life.
Eternal calm in the sun
Shapiro and his colleagues learned about a new unusual and presumably unique line of the Sun. They observed fluctuations in the brightness of 369 stars distant from us, which were constantly monitored by the GAIA orbital observatory or studied in the past the Kepler telescope.
Fluctuations in the brightness of stars, as scientists explain, show how many spots are on their surface at any given moment in time. In turn, their number on the Sun and other stars is directly related to how often flashes and other forms of activity appear on their surface. As a rule, the fewer spots on the surface of the star, the less often there are powerful flashes and emissions of coronal matter.
It turned out that in comparison with stars of similar sizes and masses, which Kepler and GAIA have been continuously observing for about four years, the number of spots on the Sun remains almost unchanged. For comparison, the brightness of the Sun on average increased and decreased by 0.07%, while for most other stars this indicator was approximately five times higher.
In practice, this means that the Sun is much more relaxed than other stars of similar sizes, mass, temperature and brightness. Moreover, an analysis of the proportions of beryllium and carbon isotopes in tree rings and ice deposits in Greenland shows that the Sun has been behaving this way for at least 9 thousand years.
On the one hand, scientists admit that such a lull on the Sun is only temporary, although long-term, by the standards of mankind. However, they do not exclude the fact that it can have a permanent character. This assumption is due to the fact that the magnetic activity of sun-like stars should sharply decrease at that moment in time when their rotation speed drops to a certain point and their bowels are sharply rebuilt.
Something similar could have happened recently to the Sun. This would explain the differences in the frequency of the appearance of spots in comparison with other stars, as well as why in recent years there has been a lull unusual in our standards, even by its standards, the authors conclude.
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