Researchers from the Leibniz Institute for Astrophysics Potsdam (AIP) and the HUN-REN Astronomy and Earth Sciences Research Center analyzed more than 2,000 high-resolution light spectra collected over 16 years by the STELLA AIP robotic telescope in Tenerife. This trove of data allowed the researchers to reconstruct 99 time-series images showing the evolution of XX Trianguli surface starspots from 2006 to 2022.
One of the main findings of the above research shows that the surface changes of the XX Trianguli star spots do not follow the same magnetic cycles as the Sun. According to the authors, the reason for this can be the non-periodic and variable nature of the star and the movement of conductive materials inside the star. Juliette Quarry, one of the authors of the study, said in a statement:
Sunspots are the most well-known signs of the Sun’s magnetic activity, which, along with many other phenomena such as solar flares or the solar cycle, can be related to the internal dynamic mechanism of the Sun. Large fluctuating changes in the brightness of the red giant XX Tri had been observed before, so these changes were determined to be caused by dark spots that disappear and appear over 24 days as the star spins on its axis. These spots are even larger than the entire surface of our Sun, which is why XX Tri has earned the title of the most spotted star in the sky.
The recent research was the first to show how very large starspots can cause small shifts in where a star appears in the sky. While the center of a uniform starlight (spotless) appears where its geometric center is, massive starspots can deflect the center of light in the opposite direction of its starspots.
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For XX Trianguli, which is 630 light-years from Earth, the center of light of the star’s disk can be displaced by up to 10% of the star’s radius relative to its geometric center, which causes a 24 microarcsecond shift in the star’s apparent position on the sky (equal to the diameter of a hair in distance of 1000 km). While this seems small, even such small differences can add up over vast intergalactic distances.
While this research helps astronomers understand the behavior of starspots and their internal changes, it can be a reason to appreciate a star whose activity is mostly predictable.
The study of scientists has been published in the journal Nature Communications.
