# Magnetic Evolution and the Disappearance of Sun-like Activity Cycles

## TL;DR

This paper explores the evolution of Sun-like star activity cycles, proposing that the solar cycle is lengthening and may eventually disappear as stars transition through a magnetic phase, based on stellar data and future observational prospects.

## Contribution

It reinterprets stellar cycle data to suggest the Sun's activity cycle is in transition and may vanish in the next 0.8-2.4 billion years, highlighting a new evolutionary perspective.

## Key findings

- The solar cycle may be lengthening over stellar evolutionary timescales.
- The solar cycle could disappear in 0.8-2.4 billion years.
- Stars in a magnetic transition phase exhibit different cycle properties.

## Abstract

After decades of effort, the solar activity cycle is exceptionally well characterized but it remains poorly understood. Pioneering work at the Mount Wilson Observatory demonstrated that other sun-like stars also show regular activity cycles, and suggested two possible relationships between the rotation rate and the length of the cycle. Neither of these relationships correctly describe the properties of the Sun, a peculiarity that demands explanation. Recent discoveries have started to shed light on this issue, suggesting that the Sun's rotation rate and magnetic field are currently in a transitional phase that occurs in all middle-aged stars. Motivated by these developments, we identify the manifestation of this magnetic transition in the best available data on stellar cycles. We propose a reinterpretation of previously published observations to suggest that the solar cycle may be growing longer on stellar evolutionary timescales, and that the cycle might disappear sometime in the next 0.8-2.4 Gyr. Future tests of this hypothesis will come from ground-based activity monitoring of Kepler targets that span the magnetic transition, and from asteroseismology with the TESS mission to determine precise masses and ages for bright stars with known cycles.