Red Giant XX Trianguli Has Massive Starspots, Dubbed the ‘Most Spotted Star in the Sky’

A massive starspots were reported on the red giant star XX Trianguli, situated approximately 630 light-years away from Earth. These starspots, which exceed the total surface area of the sun, have earned the star recognition as the “most spotted star in the sky.” Reports indicate that these spots behave unpredictably, unlike the sun’s cyclical sunspots, hinting at more turbulent internal processes. As per sources, researchers from the Leibniz Institute for Astrophysics Potsdam (AIP) and the HUN-REN Research Center for Astronomy and Earth Sciences (HUN-REN RCAES) conducted the study using AIP’s STELLA robotic telescope in Tenerife.

In a study published in Nature Communications on December 4, over 2,000 high-resolution spectra collected from 2006 to 2022 were analysed, enabling the creation of 99 time-series images depicting the progression of starspot activity on XX Trianguli’s surface.

Chaotic dynamo mechanism identified

According to Zsolt Kővári, co-author and researcher at HUN-REN RCAES, in a statement, the starspots arise due to the star’s internal dynamo mechanism, which generates magnetic fields. Speaking to media outlets, Kővári explained that the star’s brightness variations, caused by dark spots rotating in and out of view every 24 days, had been observed previously. He added that XX Trianguli’s magnetic dynamo appears chaotic and non-cyclic, differing fundamentally from the sun’s periodic activity.

Starspots alter star’s apparent position

The study further highlighted how these enormous starspots affect the star’s photocenter, or centre of light. Reports suggest the photocenter can shift by up to 10 percent of the star’s radius, causing a displacement of 24 micro-arcseconds. While minute, such deviations can result in measurable positional changes across interstellar distances.

The observations offer valuable data for understanding stellar magnetic activity and internal dynamics, positioning XX Trianguli as an extraordinary case for the study of starspots.