(ORDO NEWS) — The number of sunspots usually varies according to a predicted 11-year cycle, but one unusual 70-year period, when the frequency of sunspots dropped sharply, has intrigued scientists for the past 300 years.
Now, a nearby solar-type star has also shown a cycle pause and the start of a similar period characterized by a minimal number of starspots, according to a team of researchers from Pennsylvania State University, USA.
Star spots are observed as dark spots on the surface of a star, due to lower temperatures in this zone, the decrease of which is associated with the dynamo of the star – the process of generating a magnetic field.
Astronomers have been recording changes in the frequency of sunspots since the epoch of Galileo in the 1600s, so significant observational material has now been accumulated on the 11-year cycle of solar activity.
The exception is the Maunder minimum, which lasted from the middle of the 17th century to the beginning of the 18th century and has remained a mystery to astronomers ever since.
“We don’t know what exactly caused the Maunder Minimum, and we’ve been observing other sun-like stars in search of an answer to this question,” said Anna Baum, an undergraduate student at the University of Pennsylvania at the time of the study and first author of the new work. “We have found a star that we believe has entered a state similar to the Maunder Minimum.”
This star – dubbed HD 166620 – has a cycle of about 17 years, but has now entered a low-activity state and has not shown signs of sunspots since 2003, according to Baum’s team.
“The debate in the scientific community about the nature of the Maunder Minimum continues to this day,” Baum said. “Did the Sun’s magnetic field ‘turn off’ completely? Did the dynamo disappear during that period? could be registered?
According to the authors, a deeper understanding of the activity of the Sun’s surface and its magnetic field can lead to important conclusions that will allow more accurate forecasting of the level of solar activity, also called “space weather”.
Increased solar activity leads, for example, to the failure of satellites and global communications systems. In addition, obtaining new information on the star HD 166620 will help in the search for new planets located outside the solar system, Baum added.
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