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takyon writes:

Astronomers have found a star, HD 173701, with a similar mass, radius, and age to our own Sun, but twice the metallicity:

The spots on the surface on the Sun come and go with an 11-year periodicity known as the solar cycle. The solar cycle is driven by the solar dynamo, which is an interplay between magnetic fields, convection and rotation. However, our understanding of the physics underlying the solar dynamo is far from complete. One example is the so-called Maunder Minimum, a period in the 17th century, where spots almost disappeared from the surface of the Sun for a period of over 50 years.

Now, a large international team led by Christoffer Karoff from Aarhus University has found a star that can help shed light on the physics underlying the solar dynamo. The star is located 120 light years away in the constellation of Cygnus, and on the surface, the star looks just like the Sun: it has the same mass, radius and age -- but inside, the chemical composition of the star is very different. It consists of around twice as many heavy elements as in the Sun. Heavy elements here means elements heavier than hydrogen and helium.

The team has succeeded in combining observations from the Kepler spacecraft with ground-based observations dating as far back as 1978, thereby reconstructing a 7.4-year cycle in this star. "The unique combination of a star almost identical to the Sun, except for the chemical composition, with a cycle that has been observed from both the Kepler spacecraft and from ground makes this star a Rosetta Stone for the study of stellar dynamos." explains Karoff.

The Influence of Metallicity on Stellar Differential Rotation and Magnetic Activity (DOI: 10.3847/1538-4357/aaa026) (DX)

Original Submission