Amit Oren
Direct link to this page: https://www.hayadan.org.il/sun051104.html
An international group of researchers, led by Sami K. Solanki from the Max Planck Institute for Solar System Research in Katlenburg-Lindau, Germany, built a first-of-its-kind model that aims to quantitatively reproduce the sun's activity on Over the past 11,400 years (meaning: since the last ice age on Earth), the scientists analyzed isotopes to achieve their goal Radioactives taken from trees that grew and lived thousands of years ago; according to the report of scientists from Germany, Finland and Switzerland to the science magazine "Nature", it is necessary to "go back" 8,000 years in order to study those periods when the sun was as active as it was in the last sixty years Statistics and drawing conclusions from periods when there was accelerated solar activity, the researchers predict that the high level of the sun's activity will last for several decades only.
Already in 2003, the research team found evidence that the sun was more active than it was in the previous millennium and new data they obtained allowed them to expand the studied time domain to 11,400 years. This study showed that the current period of high solar activity (which began in 1940) is unique to the last 8,000 years. This means that more spots and more volcanic eruptions were produced on the surface of the sun than before this period. It should be noted that the result of these volcanic eruptions is finally the emission of huge clouds of gas and matter into space, which sometimes reach the Earth. The Sun's magnetic field is to blame for these phenomena.
Since the invention of the telescope in the early seventeenth century, astronomers have observed sunspots on a regular basis. The spots are areas on the sun's surface where the energy supplied from the sun's interior is reduced due to the strong magnetic field that surrounds them. As a result: sunspots are at least 1,500 degrees colder than the rest of the surface around them (5,800 Kelvin - the average surface temperature, 4000 Kelvin - the average temperature of a sunspot), and appear darker compared to their neighbors who lack the self-magnetic field. The number of spots visible on the sun's surface varies throughout the eleven years of the solar cycle, which is regulated by changes in the long meridian. For example: there were almost no sunspots in the second half of the seventeenth century.
For many studies concerning the subject of solar activity and its potential effect on periodic changes in climate, such as DHA, the period in which the research theoretically begins is approximately 1610 (the first year of which there is actual and recorded evidence regarding sunspots). But this allotted time period is too short, and -In order to obtain information about the activity of the sun in earlier periods, data from secondary sources must be analyzed. Such sources are, for example, the cosmogenic isotopes; Radioactive nuclei formed as a result of collisions of cosmic ray particles with the air molecules in the upper layers of the atmosphere. One of these isotopes is C-14; a radioactive carbon with a half-life from its initial amount) of about 5730 years. This type of carbon is often used to measure and determine the age of objects The amount of carbon 14 produced depends significantly on the amount of cosmic rays (and their charged particles) that reach the atmosphere. Thus attracting them to the sun itself and preventing them from reaching us - while the power of the cosmic rays is strengthened when the solar activity is low. Therefore, it can be said that high solar activity leads to a lower production of C-14, and vice versa.
In various fusion processes in the atmosphere, the carbon-14 reaches the biosphere and part of it integrates into the biomass (total weight of organisms in a given area unit) of trees. Certain tree trunks can be brought up from under the ground even thousands of years after their death, and the C-14 content preserved in them can be measured. The year in which the carbon-14 merged in those trees was determined by comparing different trees and overlapping lifetimes. With this method, it is possible to measure the output of C-14 over 11,400 years, until the end of the last ice age. The research group used this information on In order to calculate the deviation in the number of sunspots over the last 11,400 years, the number of sunspots is also a good measure for The strength of other solar phenomena.
The method of reconstructing solar activity was tested and measured by comparing evidence and historical records of sunspots against reconstruction models built on the basis of the particles of the cosmogenic isotope Be-10 (beryllium ten) found at the KDA poles. The models concern the production of the isotope by cosmic rays. The direction of the cosmic ray is constantly changed by the interstellar magnetic field, as well as the relationship between the giant solar magnetic field and the number of sunspots. In this way, for the first time it is possible to build a fairly reliable reconstruction of the number of sunspots from the end of the last ice age to the present day.
Since the sun's brightness varies according to its activity, the reconstruction indicates that the sun is brighter today than it was 8,000 years ago. Admittedly, it is not known whether this effect had a significant effect on global warming [Global Warming - an increase in the average temperature of the Earth, as a result of the greenhouse effect]. The researchers working with Solanki [Solanki], the leader of the project, emphasize the fact that the activity of the sun has remained constant and higher than approximately 1980, and apart from the deviations created due to the 11-year warm cycle - the global temperature rose noticeably in the same period. On the other hand, the tendencies of the solar activity and the relationship between it and the terrestrial temperature throughout the last centuries (with a considerable exception of the last twenty years) show that the connection between the sun and its activity on the terrestrial climate remains a challenge for continuous research.
First retrieved from: Max Planck Society News Release
For the news in Universe Today
Translated by: Amit Oren.
The Israeli Astronomical Society
The solar knower
https://www.hayadan.org.il/BuildaGate4/general2/data_card.php?Cat=~~~996017298~~~12&SiteName=hayadan
