In their new scientific paper, a group of astronomers from the University of Wrocław presented the first in history direct connection of a flare with a spot on a star other than the Sun.

In the observation data of the TESS mission a rare, long-duration flare on a fast-rotating, only 40 million years old, star CD-36 3202 was identified. This K2 type star rotates 120 times faster than the Sun and is located 90 parsecs from us. Detection of the flare was hampered by modulation of the star’s brightness caused by dark spots on its surface. In order to extract the brightness curve of the flare, it was necessary to build a model of the distribution of spots beforehand. The corrected brightness curve revealed that it is the longest known stellar flare lasting as long as 27 hours.

The brightness curve still demonstrated a variability associated with the rotation of the star, i.e. the so-called rotational modulation. Close inspection of the curve allowed recreating the location of the flare area on the star’s surface, which turned out to be inside one of the massive photospheric spots. To date, relations between flare areas and spots had only been observed for the Sun. In the case of most sun flares, they are located in active areas, i.e. groups of spots. However, for other stars observing photospheric spots is hindered. Analysis of changes in brightness allows, among others, to recreate the size of spots that are usually bigger than in the case of the Sun. We do not rule out that the spot where the flare occurred is an extensive active area on that star.

This result is the first direct recreation of the location of a flare in relation to a star other than the Sun, which is a significant step in understanding these phenomena.