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If you follow EarthSky\u2019s daily sun news, you know an active sun has many sunspots, or temporary dark spots on its surface. Our sun is a star, so it\u2019s no surprise that distant stars have dark spots, too. Astronomers call them starspots. On December 4, 2024, astronomers at Konkoly Thege Mikl\u00f3s Astronomical Institute in Hungary said they\u2019ve mapped starspots on a star called XX Trianguli. They found this star has enormous spots, bigger than our entire sun! But, unlike our sun \u2013 which waxes and wanes in activity over an 11-year cycle \u2013 XX Trianguli appears to lack a regular cycle of producing spots.<\/p>\n
The researchers published their study in the peer-reviewed journal Nature Communications<\/em> on December 4, 2024. <\/p>\n XX Trianguli is located in the direction of our northern constellation Triangulum. It\u2019s about 642 light-years away. And this star is about the same mass as our sun. But the star is about 10 times bigger than our sun, because its outer layers have expanded outward. <\/p>\n In other words, XX Trianguli is a red giant, near the end of its evolutionary lifetime. Zsolt Kov\u00e1ri, at the Konkoly Observatory in Hungary, explained:<\/p>\n The large-amplitude variations in the brightness of the red giant XX Trianguli have been observed before, so it was also known that the variations were caused by dark spots, coming in and out view as the star rotates around its axis in 24 days. These spots are even larger than the entire surface of our sun, which is why XX Trianguli has been dubbed \u2018the most spotted star in the sky.\u2019<\/p>\n<\/blockquote>\n The creation and maintenance of our sun\u2019s magnetic field is thanks to what scientists call a solar dynamo. The movement of charged particles inside the sun, and the sun\u2019s rotation, are the main drivers of this dynamo.<\/p>\n Characteristics of the sun\u2019s magnetic field, in turn, drive the 11-year sun cycle of activity. Each cycle sees an increase, then a decrease, in sun surface phenomena such as solar flares and sunspots. Throughout 2024, our sun has been extremely active. Experts at NASA believe it reached the peak of the current sunspot cycle this fall.<\/p>\n In contrast, the distant star XX Trianguli doesn\u2019t have a regular sunspot cycle. In fact, the astronomers said its dynamo is <\/p>\n \u2026 Non-periodic, most likely chaotic in nature.<\/p>\n<\/blockquote>\n Kov\u00e1ri commented:<\/p>\n The solar dynamo shows a cyclic behavior in the number and distribution of sunspots that repeats every 11 years on average, known as the butterfly diagram. However, XX Trianguli is a red giant star about 10 times larger than the sun and its internal structure differs significantly from the sun\u2019s, which is a main sequence dwarf. We found no evidence of similar cycles for XX Trianguli.<\/p>\n By studying stellar dynamos, we can also get closer to understanding the solar dynamo. Moreover, dynamo operation is not only responsible for the magnetic features on the sun or other spotted stars, but also the Earth\u2019s magnetic field is created by a similar mechanism, which, on the other hand, happens to protect our technical civilization from harmful solar storms. <\/p>\n Our goal is to be able to observe the manifestations of the dynamo mechanism in as many stars with different characteristics as possible, since by knowing the similarities and differences, we will ultimately better understand the processes that shape our own environment.<\/p>\n<\/blockquote>\n\n
The sun\u2019s a pretty stable star<\/h3>\n
XX Trianguli\u2019s starspots show it\u2019s a chaotic star<\/h3>\n
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