(ORDO NEWS) — Spots are sometimes formed on the Sun – dark areas on the surface of a star.
They are created by strong magnetic fields that suppress vortex movements and prevent light from escaping freely. On other stars, these phenomena are called star spots.
Astronomers have developed a new technique for identifying star spots.
“Our study is the first to accurately characterize star spots and use them to directly test theories of stellar magnetism,” said Lira Cao, lead author of the study.
“This method is so accurate and widely applicable that it could become a powerful new tool in the study of stellar physics.”
Using this method, Cao and her colleagues will be able to publish a catalog of starspot and magnetic field measurements for more than 700,000 stars.
By analyzing high-resolution infrared spectra from the Sloan Digital Sky Survey, Cao was able to develop a technique for identifying star spots on 240 stars from the Pleiades and M67 star clusters.
The study found that precise measurements of star spots are a powerful new class of data that could help scientists understand how stellar magnetic fields work.
Due to the accuracy of the method, Cao was also able to see how age and rotation affect the magnetic fields of stars.
“It was hiding in plain sight: there was a colder component in the spectrum, corresponding to a star spot that was only visible in the infrared,” Cao said.
Cao realized that these large and cold regions could block so much light that it could have a measurable effect on the stars.
Because the light must eventually scatter, the star expands and cools to make more surface area available for radiation, she said.
The researchers also found that relying on classical methods for estimating the temperatures of these stars could be off by more than 100 degrees.
Because scientists often use the temperature of a star when trying to estimate its size, astronomers may mistakenly assume that a star’s radius is smaller than it actually is.
In addition, the researchers found a class of stars in the Pleiades cluster that are too active to be explained by standard theories.
These stars are not only magnetic and teeming with star spots, but also brimming with ultraviolet and X-ray radiation, Cao said.
The study notes that further study of these unusual stars could provide clues as to why low-mass stars are so active.
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