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The sun appears to be much less active than similar stars in terms of brightness variations caused by sunspots and other phenomena, a “boring” personality, according to scientists, that may not be a bad thing for us Earthlings.
Investigators said Thursday that an examination of 369 sun-like stars in surface temperatures, size and rotation period, takes the sun about 24-1 / 2 days to rotate once on its axis, showed that they showed on average five times more variability in brightness than the sun.
“This variability is caused by dark spots on the star’s surface that rotate in and out of view,” said astronomer Timo Reinhold of the Max Planck Institute for Solar System Research in Germany, lead author of the research published in the Science magazine. “A direct measure of solar activity is the amount of sunspots on the surface.”
The sun, essentially a hot ball of hydrogen and helium, is an average-sized star that formed more than 4.5 billion years ago and is about halfway through its lifespan. Its diameter is approximately 1.4 million km. Its surface temperature is about 5,500 degrees Celsius.
“Temperature and rotation period are believed to be the main ingredients for the dynamo within the star, which generates its magnetic field and ultimately the number and size of the dots that cause brightness to vary. Finding such stars with parameters very similar to our sun but being five times more variable was surprising, “Reinhold said.
The high magnetic activity associated with sunspots can cause solar flares, coronal mass ejections (large ejections of plasma and magnetic field from the outermost part of the sun’s atmosphere), and other electromagnetic phenomena that can affect Earth, for example , disrupting satellites and communications and endangering astronauts. .
Solar monotony can be good news.
“A much more active sun could also have affected Earth on geological time scales: paleoclimatology. An “overly active” star would definitely change living conditions on the planet, so living with a rather boring star is not the worst option, “Reinhold said.
The researchers compared data on similar stars with historical records of the sun’s activity. These records included about 400 years of observational data on sunspots and about 9,000 years of data based on variants of chemical elements in tree rings and ice cores caused by solar activity. These records indicate that the sun has not been much more active than it is now.
The findings, Reinhold said, do not rule out that the sun may be in a quiet phase and may become more variable in the future.
