Activity of Selected Solar Twins

TL;DR

This study investigates magnetic activity, rotation, and flares in 23 solar twins, revealing significant variability in their coronal activity, rotation rates, and flare energies, and exploring links to stellar age and magnetic phenomena.

Contribution

It provides a comprehensive analysis of magnetic activity and flares in solar twins, including rotation periods and flare energies, with new insights into their age and magnetic properties.

Findings

Wide scatter in X-ray to bolometric luminosity ratios among stars.

Detection of fast rotation periods around 6 days indicating youth.

Observation of large, long-duration stellar flares with energies up to 8×10^{33} erg.

Abstract

We analyze various tracers of magnetic activity for 23 solar twins which are characterized by significant scatter of lithium abundance in their atmospheres. A level of coronal and chromospheric activity has been studied from available X-ray and UV-archival data. It gives us a chance to compare coronae of solar twins of various ages with the solar case. We found a scatter in the X-ray to bolometric luminosity ratio $L_X/L_{bol}$ by several orders of magnitude, which exists in these stars along with a significant spread in Li abundance. This may link the surface activity of stars with phenomena at the base of their convective zones. The TESS data allowed us to reveal rotation modulation of stellar brightness associated with starspots. For some twins of our samples, periods of axial rotation are detected around 6 days, i.e. these stars rotate almost 4 times faster than the contemporary Sun. This indicates their relative youth. Flare activity of solar twins is discovered in the TESS data; we showed existence of various kinds of flares, and present temporal profiles for some of them. We obtained the energy about of $8 \times 10^{33}$ erg for the largest flare of our samples, lasting longer than 4 h. In addition, we discuss also magnetic fields and exoplanets, orbiting these stars.