Evolution of Long Term Variability in Solar Analogs

Abstract

Abstract. Earth is the only planet known to harbor life, therefore we may speculate on how the nature of the Sun-Earth interaction is relevant to life on Earth, and how the behavior of other stars may influence the development of life on their planetary systems. We study the long-term variability of a sample of five solar analog stars using composite chromospheric activity records up to 50 years in length and synoptic visible-band photometry about 20 years long. This sample covers a large range of stellar ages which we use to represent the evolution in activity for solar mass stars. We find that young, fast rotators have an amplitude of variability many times that of the solar cycle, while old, slow rotators have very little variability. We discuss the possible impacts of this variability on young Earth and exoplanet climates.

First long-term activity study of AU Microscopii: a possible chromospheric cycle

“…However, the statistics is still low in comparison to solar-type stars (Baliunas et al 1995;Hall et al 2007;Lovis et al 2011;Egeland et al 2017;Flores et al 2017). Therefore, the detection of new accurate activity cycles for low-mass stars could bring valuable observational evidence to explore the dynamo theory in this spectral class.…”

Spectropolarimetry of Stars Across the H-R Diagram

“…However, not all active stars undergo smooth activity cycles and the activity of the most active stars has the tendency to fluctuate erratically, while regular activity cycles are observed in older stars. Egeland et al (2017) studied the long-term variability of a sample of five solar analog stars using composite chromospheric activity records up to 50 years in length and synoptic visible-band photometry about 20 years long. Their sample covered a large range of stellar ages, which they used to represent the evolution of activity for solar mass stars.…”